SOLAR PANEL INFO SOLAR PANEL INFO What is PV & how does it work? PV stands for photovoltaic. Photo = Light and Voltaic = Electricity. A solar cell converts light to electricity. A solar cell is made of silicon. Computer chips are made of this same material. Basically, when light strikes the surface of a solar cell some of it is absorbed into the silicon. This light energy bumps the electrons loose and causes energy to flow. By packaging approximately 36 solar cells together a solar panel or a solar module is created. When you have more then one solar panels you create a solar array. What makes up a PV system? What is BOS? BOS stands for Balance of System. For a complete system you will need more than just a solar panel. Here is a short list of other components that might be required for your system. Solar Panel Mount Inter Module Wiring Output Cable Charge Controller Fusing Battery SOLAR PANEL INFO e Low Voltage Disconnect, This is built into most charge controllers e Inverter, For AC power System Setup: Solar---Charge Controller---Battery---Inverter---AC Loads or Solar---Charge Controller---Battery---DC Loads What kind of inverter do I need? The type and size of inverter necessary depends on your application. To determine this you must first calculate the maximum amount of load you will be running on the inverter at one time. There are basically four size ranges of inverters. The first is 50-300 watts; these are small portable inverters. These inverters are ideal for laptops, small lights and other minimal draw AC loads. The next size range is 300-800 watts. These are also somewhat portable and still have the outlets on the front of the inverter. This size inverter is good for small microwaves and other small appliances. The third range is from 800-2000 watts. These units usually have battery chargers built into them. Your can recharge your batteries with utility power or generator power. They are also great for powering medium size AC loads, or running multiple smaller loads at one time. These units are typically permanently installed. The final inverter grouping is a permanently installed units ranging 2,000-11,000 SOLAR PANEL INFO watts. They function much like small generators, yet are completely silent in operation. They are great for your larger loads, such as refrigerators. The other question that needs to be answered when selecting an inverter is the type of wave form. If you are running sensitive electronic equipment, like fax machines, laser printers or high tech stereo equipment you need a sine wave inverter. A sine wave inverter has a wave form that is very similar to the form of grid electricity. Other options may include modified sine wave, which is fine for items that are not supersensitive to clean power. You may experience a humming sound when powering clocks, and small radios on a modified sine wave inverter. What Kind of Battery do I need? The most common type of battery used in a solar system is a lead-acid battery. They are generally used because they have a low initial cost and are readily available. These batteries must be deep-cycle batteries. If the battery is a shallow cycle or automotive type it will not function correctly in the system. The deep cycle batteries are designed to discharge and recharge or cycle day after day for years. The next decision is whether the batteries are sealed or flooded. A sealed battery never needs water added nor does it need an equalization charge. The benefits of this battery are; the battery can be mounted in any position and are easy to transport. The one downside is that they need to be monitored closely as to not overcharge. A flooded battery also needs close attention. The water level needs to be checked often and re-filled. You will also need to perform an equalization charge, which is a long steady controlled overcharge. This removes sulfation from the battery plates. While this restores the battery's capacity, it can lessen the life of the batteries by warping the plates. So you need to decide which battery fits your specific needs. As long as the battery is taken care of you can expect a long battery life using either battery type. When do I need a charge controller and why? SOLAR PANEL INFO The safest way to figure out if you need a charge controller is to take Battery Amp Hour Capacity and divide this by the Solar Panel max. power amp rating. If the quotient is above 200, you don't need a controller. If the number is less than 200 than you need a controller. For example if you have a 100 amp hour battery and a 10 watt panel, you take 100 and divide it by .6 (600mA) and you get 166.6. Since this is less than 200 you need a charge controller. If you have a five-watt panel in the above example you take 100 divided by .3 (300mA) and you come up with 333.3. Since this is larger than 200 you do not need a charge controller. However you still need a blocking diode, to prevent the battery from discharging to the panel at night. So as a general rule of thumb you don't need a charge controller unless you have more than five watts of solar for every 100-amp hours of battery capacity. How do I wire my batteries for different voltages? There are two major terms in battery wiring: series, and parallel. Parallel wiring keeps the voltages the same, while increasing the capacity. Parallel can be described as positive to positive, negative to negative. Here is an example of paralleling four batteries in a 12volt system. 12¥ INVERTER Series connecting increases the voltage in a system, while capacity of the battery bank remains the same. Here is an example of series connecting four batteries together to create a 48volt system, and a 24volt system. Then paralleling the 24 and 48volt banks with another 24 and 48volt bank to increase capacity. SOLAR PANEL INFO 46V INVERTER 24¥ INVERTER What size wire do I need? Using the below charts, find the current in amps on the left. Follow this to the left until you see the one way length of wire you need in feet. Then look straight up to the wire size at the top. For example, I want to run a 10 amp load wire 50' with 5% losses or less at 12 volt. I will need #6 AWG wire. Wire Sizing Chart Voltage} 12. Loss 5% | Wire Gauge 14/12/10'8|}6 > 4 )2 ) 1 | 1/0 | 2/0 | 3/0 | 4/0 Current (amps) 1 [106/169 269/427 679|1080 1717 2166 2730 3444 43425475 2 (53 |85 134214340/540 | 859 108313651722 2171 2738 3 |35 |56 |90 142.226 / 360 |572 | 722 |910 |1148|1447|1825 4 |27|42 67 107170|270 | 429 | 542 | 682 |861 1086/1369 5 21/34 54 85 136/216 | 343 | 433 | 546 | 689 | 868 1095 6 |18|28/)45 71 113/180 286 |361 | 455 |574 724 |913. Z 7 [15 [24 [ae [61 [97 | 184 [245 [309 [290 [492 [620 [782 (8 13/21 (94 53/85 135 215 (271 341 430 [543 684 "9 (12/19 30 47 (75/120 |191 [241/303 (983 482 608 (4011/17 (27 43/68 108 172/217 (273 344 [434 |648 "48 (7 (11/18 28/45/72 114 144 182 230/269 365 20 NA 8 18 21 34/54 | 86 |108 |136 172 (217 274 (25 NAINA|11 17/27/43 69 | 67 [109 198 [174 |219 | 30 NAINA) 9 |14/23| 36 | 57 | 72 | 91 |115 | 145 | 183 95 NANANA 12/19 31 49 62 | 78 | 98 |124|166 "40 \NANANANA|17| 27 (43 | 54 | 68 66/109. 197 "45 NANANAINA/15 2438 48 61 77 96 122 "50 |NANAINANA|14 22 [34 43 55 69 | 87 [110 "55 NANANANA 12/20 |31 | 39/50 63 79 100 "60 NAINANANA 11 18 29/36 45 577291 1818 Wire Gauge vafreito[s [6 [4 [2 [1 [10 [20 [a0 [40 -| oO O|= nm| © n|aQ 0) (eo) (143 [68 107/171 [2721492 687 866|1092 1877/17872190 "2 21/34 54 (85 136216349 493 546 689 868 1095 "3 14/23 96 57 (91 144220289 364 459 579 730 4/11 17/27 43 68 108172217 273 (344 [434 (548 "5 (9 14/21 (34 54 (86 197179 218 275 [347 (498 (6 (7 11/18 [28 45 |72 114/144, 182 (290 [289 | 365 28888 fereeels es EEeifeesavense BlGaveeeassnan B8a8rgssananee ASsssesxeaRgaecie = Bigeiseisslaiae ies |sie B18 |S |9 [8 \N E/E SE |S |e oo [n 8/8 |B |8 (2 |F = |e |@ |n |o [w |w wo S\N [PF [Elo [s |e |» [S|s [S| [FE Plelsle lls Sis elses [S |w |w |m jo |o |S SF S/S |S |S SS ow lo +o |S SS S/S SS S'S aided ddd did ee aee Wire Gauge a4 [i2[t0/e [6 [4/2 [1 [10 |20[a0 | 40 4332 2166 1444 1083 866 722 m miOD\a|oin 5 4 171 6 (35 56 90 142) 226 | 360 Voltage Current (amps) (24 Loss 5%. — OLAR PANEL INFO SERBESSRR LEE SS SERBS SSR SRS S RE BBESERG SSS a oss SseeRek sss ssee S§BShebiasesas BRaSteeesneess SEGBseaeass nee SSS RS BEE 7 [30 (48 [77 8 7 2 67 9 a4 8 00 95 “1021 (34 54 85 1514 28 96 67 20 NA/T7 25 NAINA 30 NANA 18 "a5 NANA NA 24 40 NA|NA NA NA ~ 45 NA|NA NA NA 50 _NA\NA NA NA 55 NANA NA NA ~60_NA|NA NA NA iiivs geese Ebeas zaR38 Bages BBE3e HIBS SIRE (B/S) SEES EER Bie Bigies & Cais on as Wire Gauge 4[t2 [10/8 [6 [4 | 2 | 1 |W [20 [9040 24 59, r— Voltage Loss (459 [579 [730 7 12/49 81 49 78 123/196 248 312 304 496 626 "8 (11/17 27/43 [68 108 172 217 273 344/404 548 9 | 9 |15 24/38 |60 |96 |153 |193 |243 |306 | 386 | 487 10 |9 |14|21 |34 [54 |86 /137 /173 |218 |275 |347 | 438 78 (6 9 (14 23/96 58 92 116 146 | 14 [232 202 — —-| WO AlN a OD) | © — —b (oo) SoEEEEC EL ages 08 Voltage 48° Loss 5%. r— Wire Gauge 4 [12[10[8 [6 | 4 [2 | 1 | 1% | 20 | 30 | 40 Current (amps) "1 425 676 107417092717 4320 (6869 8664 10919 13774 17369|21902 "2 213938 637 854 1959 2160 3434 4332 5460 6887 8684 10951 "3 142225 358 570 906 144022902888 3640 4591 5790 7301 "4 106 169/269 427 679 1080 1717 2166 2730 3444 4342 (5475 jUSE22E2 rea ans cEEEEREaNSsanaza EUELESceagasneas ZESADSrsuazceess EERE SSE Ss RSE SEBS EES BEBSS ERE EERE ERERSSRSL TS 8s see ERRSSS SEB alee es ee SRSESEZ sabes 323i Se ese2besessiss ss 8 |F |S (8 2 Bie , S55 |B |5 |e a cheer 2) NA 36 25 NANA 43 30 NA NA/ 36 ~35__NAINA NA ~40_NAINA NA 45 NANA 50 NANA 55 NANA NANA NANA 60 Wire Gauge va[lio[s[s [4 [2 | 1 [1/20 [30 [40 3466 1733 eis) LE Hae Learn to size a basic solar system Learn to size a basic solar system. The following is a sizing sheet that can be used to approximate the size of a solar system. Atlantic Solar uses computer programs to determine the final size of the solar system needed to meet a specific load requirement. For an estimate of a solar system size this process will work just fine. It is suggested that you print this page and fill in the blanks step by step. Please note all mathematical operations are listed as follows: (X) is multiplication, (/) is division and (=) is the result. Step #1 Daily DC Load Calculation Hours/Day(X)|[Days/Week(=) pepe Total AH/Week (=) otal AH/Week(/)|/7 Days/Week(=)||[Average AH/Day, DC Loads ———— ae Step #2 Learn to size a basic solar system Appliance power ratings can be found on the back of almost every appliance. The rating is found on a label that states the power consumption of the unit in wattage. Motors need additional power to start, this is referred to as the surge of the appliance. The surge rating is located on the same label as the power rating. Daily AC Load Calculation IName a Max. Surge (Add worst surge to continuous loads Total WH/Week(/)||7 Days/Week(=)||Average WH/Day, AC Loads a baWek Make Inverter Choice Inverter Specifications. Inverter Choice = Learn to size a basic solar system Continuous Load : Watts (MUST be greater than Capacity ~ Max. Continuous Load) Watts (MUST be greater than Surge Capacity = Ne Siise) Input DC Voltage a match DC Load Account for Inverter Efficiency Average WH/Day, .88 Average Inverter Adjusted DC AC Loads(/) Efficiency(=) WH/Day ee Convert AC Load WH/Day to AH/Day Adjusted DC WH/Day(/)Inverter Input Voltage(=)Total AH/Day Step #3 Total Average AH for AC and DC Loads (only if both are the same nominal voltage) Total AH/Day, DC Total AH/Day, AC Loads(+) Loads(=) Rovere oo) Step #4 Learn to size a basic solar system Find your site's location on the insolation maps. City, State, Country of Site//Worst Case Hours of Insolation Step #5 Size the PV Array Loss/Recharge Min. Size of PV AH/Day(/) Factor(/) Site Insolation(= di eeded in Amps ee Determine the Number of Parallel Modules Solar Module Specifications. Round Up to Whole Module Amps @ Peak Number, Power(=) Total Parallel Modules Needed Solar module model number that was used in above calculation. Determine the Number of Series Modules Nominal System a satae asad Total Series Modules Voltage, Typically 12V(E) Needed Voltage(/) file:///C|//Documents%20and%20Settings/Administ...n%20to%20size%20a%20basic%20solar%20system.htm (4 of 6) [4/7/2002 3:11:55 PM] Learn to size a basic solar system Pd Determine the Total Number of Solar Modules otal Series Modules(X)|Total Parallel Modules(=)/Total Modules Step #6 Size the Battery Bank Needed in AH Temperature Correction Factors Lowest 24 Hour Temperature emperature Range in Degrees CCorrection Facto When determining the number of parallel batteries needed for your system, use the largest single battery possible. This is to keep the total number of parallel cells to a minimum. The more batteries in parallel the greater system losses. file:///C|/Documents%20and%20Settings/Administ...n%20to%20size%20a%20basic%20solar%20system.htm (5 of 6) [4/7/2002 3:11:55 PM] Learn to size a basic solar system Determine the Number of Parallel Batteries Battery Specifications. Round Up to Whole Battery AH @ 1O00HR Number, Rate(=) Total Parallel Batteries Needed Needed Battery AH(/) Determine the Number of Series Batteries Nominal System Nominal Battery Total Series Voltage(/) Voltage(=) Batteries Needed Determine the Total Number of Batteries otal Series Batteries(X)|/Total Parallel Batteries(=) file:///C|/Documents%20and%20Settings/Administ...n%20to%20size%20a%20basic%20solar%20system.htm (6 of 6) [4/7/2002 3:11:55 PM] generators for. their sees cates eee ji ePriostreniaies focations-on’ the:globe ~ solar electric systems:are:working silently and reliably every day to protect. pipelines: from corrosion, = monitor air quality, and ‘accomplish many important jobs. for industry. needs. own system. How do Photovoltaics work? We can easily explain how the Photovoltaic effect produces a flow of electrons. In short, electrons are excited by particies of lignt and find the attached electrical circuit the easiest path to travel from one side of the ceil to the other. Envision a piece of metal such as the side panel of a car. As it sits in the sun the metal warms. This warming is caused by the exciting of electrons, bouncing back ana forth creating friction and therefore heat. The solar ceil merely takes a percentage of these electrons and directs them to fiow in a oath. This flow of electrons is, by definition, eiectricity. Are Photovoltaics cost effective? Yes, PV is cost effective in the right location. By this we mean where tne extension of utility lines are a major factor. We use tne figure of one-third of a mile as a rule of thumb for cost effectiveness, yet rates vary substantially from site to site. Tis thirc-of-a-mile figure is only a rule of thumb. lf you haven't already, get a quote from your iocat power company. lf you are on utility power at present - PV is not a cost effective move. Utility power is much cheaper than PV power. Why? Because we have not yet begun to pay for the externalities of fossii fuel and nuclear generating plants. When this country begins to pay for the sulfur emissions which cause acia rain, global warming ana nuclear waste disposal, to name a few, we will see power costs increase, With this in mind we need to ask and answer the question again. We believe, over the working life of a PV system, it can very well be a cost effective move. It ail depenas on the real price increases of utiity power, 2, 5, 10 ana more years from today. This Design Guide's: intended to give you an overview of wireless solar:electric systems: it explains: how systems work, what the important components are, and how to choose the proper system for your’ This publication is used in conjunction with our "Solar Electric Products Catalog" to provide you with’ all the information you need to make an informed decision. if you intend to purchase a solar electric system, this guide will provide you with the information to ask the right questions and understand the operation of your proposed system. Included are worksheets so that you can calculate the size of your It is understood that when purchasing a solar electric system, you should work with an industry professional; a company that is knowledgeable in sales and service. Our network of Authorized Dealers can help you make the right choices to soive your energy problems. Table of Contents. Introduction to Solar Power Consumption Information.... 7-10 Components of a System Solar Modules.................:.++ .. 12-413 Trackers & Mounts.......... Wind Generators ................ sreseserne 145 Charge Controllers .......ccssceceee 15° ITDVEFteY ....cccccecccecrscscscsersscsesses LOOT Battery Chargers .......cscccsssressne 17) Batterie .........sssccssccesssensorscesences LORD MIGQRITOMS wisecscssiacecvoensdcadsansssinpactcsrisacee « Water PUMPING ............ccsccccessseccceeeesree LO” GOMGPATONS ancscecsccissssessvercssvescovssevanqnecesess eo” RV SYSTEMS ...... cc cescssenccssseressesecenssne DOLE | Cabin Example System ............ 28-29° Genverter Example System « 30-31 Residential Example System.......... 32-33 Powerline Example System............ 3435" APPONIX ......scscsceseorcsssrccceees seesnee 30-41 GIOSS ANY ccccsspxcdoes scasdiscscksineiteticesevseese ae Powering Your Heating Loads Photovoltaic systems and the power they produce are best suited and most economical for operating motors, pumps, electronic equipment, lighting and the like. PV's are not recommended to run your heating loads. Appliances such as _ toasters and microwaves are not a problem because of the low running times. Yet electric ranges, water heaters or baseboard heaters simply require enormous amounts of power, and cannot be run by photovoltaics in an economically effective manner. . To power these loads we recommend thermal solar systems for space and water heating. In cloudy weather; wood and gas, either natural or propane, run these appliances efficiently and economically. In many systems we recommend propane for cooking, water heating and sometimes refrigeration. The Whole Home Approach When considering energy efficiency it is important to consider the home as a system. Most loads are related to each other. For example: a well insulated house requires not only less heating and cooling but also less energy to distribute and circulate this conditioned air. Correctly placed windows not only heat the home, but can also contribute a great deal of natural light, thus reducing both heating and lighting requirements. The home that is designed from the ground up with energy efficiency in mind will require much less of a photovoltaic power system. Trying to utilize photovoltaics to power the conventional American home with its conventional appliances can be an unnecessarily expensive project. Reflection on these costs has prompted most of our customers to look first to conservation to reduce their loads. This is a cost effective move even for those still on utility power. For those going with PV, it can mean a much smaller and less expensive system. Most of the houses which we have powered with PV do not appear noticeably different from conven- tional houses in terms of comfort and convenience. Some people do decide to adapt their life style when producing their own energy, and most of these changes have to do with simply being more conscious of shutting off loads not in use. The largest change of being your own utility is the responsibility that this entails. Almost without exception, however, the increased independence that this decision brings is cited by PV home owners as a great source of satisfaction. Solar vs. Wind vs. Hydro Power How do PV‘s compare to other alternative power sources? Pets Hoe nnn Wind generating plants require a good steady wind at regular intervals over the four seasons. If you have a site where you have this resource, power production will not be a problem. Hydroelectric generators are another option. These small generators require a healthy flow of water with good vertical drop throughout the year. Two points to look at are the site specific nature of these power sources and the differ- ence in moving parts. Solar electricity many times has the advantage with both factors, sunlight being fairly universal and PV's having no moving parts to wear and eventually fail. A combination of systems often work the a best. Many times when the clouds reduce your - solar output, wind or hydro systems are per- forming at full power. Solar Water Heating Different solar technologies are often confused. While the conversion of sunlight to electricity is photovoltaics, the collection of radiant energy to produce heat is Solar Thermal. We do not utilize photovoltaics to create heat as this is an unnecessarily complex, very indirect and inefficient way to do so. “Heating with electricity”, as Amory Lovins has put it, “is like cutting butter with a chainsaw.” The direct capture of solar radiation by heating a black collection surface, however, can be a very cost effective and efficient way to produce hot air or hot water. We do not deal with solar thermal space heating. As sensible and efficient as this technology can be, it requires a good deal of on-site engineering and is the province of solar architects. Solar water heating for household uses can also be complex, but it can also be quite simple. Electricity for Beginners Electricity can be thought of as a flow of electrons through a conductor, generally wire. This flow is often compared to the flow of water through a pipe. In this analogy, if you wish to have increased flow through the pipeline, you will need either a bigger pipe or you will have to push the water (or electricity) through at a more rapid rate. To push water through a pipeline at high speed requires high pressure. Pressure in water is measured in p.s.j., pounds per square ; : inch. You can envision water under high pressure squirting out very sel cng ie lly s bby ole om . rapidly from a nozzle, such as a fire hose, with enough speed and mushroom shaped as well. A tower designed to force (power) to carry it to great heights or to do the work of produce 50 p.s.i. for household pressure might knocking someone off their feet if they get in the way. Similarly, be built like this. the “pressure” of electron flow is called voltage and is measured in volts. Generally speaking, the higher the voltage of an electrical current, the more force behind it. The amount of flow at a given pressure is determined by the size of the cross-section of the pipe. If you were to open a spigot twice as big as another with the water in both at the same pres- sure, twice the amount of water will flow from the larger. The amount of flow in electricity is called amperage or “current” and is measured in amperes, or “amps” for short. Taking our analogy further, a battery stores electricity much as a water tower stores water. The taller this tower, the higher the pressure present at its base. If you open a valve at the base, water will flow out at a high pressure. In the same way, if you flip a switch connecting batteries to a load, electricity begins to flow. The higher the voltage of a battery bank, the greater the “pressure” of the electron flow. And just as with a tower of water, as electricity is drained from the battery, the pressure (voltage) slowly drops. Most of the water available in such a tower is available from 45 to 60 p.s.i.. Once drained below 40 p.s.i., usage will rapidly deplete the supply at an ever decreasing pressure. In the same way, a nominal 12-volt battery has most of its stored electricity available from just below 12 volts to 12.6 volts. When drained below 12 volts, little amperage remains. Just as a pump designed to fill such a tower would need to be able to produce at least 60 p.s.i. (that is, be able to lift 138 feet,) so does a solar PV module need to be abie to produce at least 15 or 16 volts in order to charge a 12 volt battery. Electrical power (the ability to do work) is a function of pressure (voltage) and amount (amperage). Double either one and you double the power the current is carrying through the circuit. The rule “VOLTS MULTIPLIED BY AMPERES EQUALS WATTS" defines this relationship. This is known as Ohm's Law. The watt is the measure of the power of electricity and will be our basic unit of measure for determining the size of our electrical loads. A one watt load that is powered for one hour will consume one watthour of power. A 100 watt load powered for 2 hours will consume 200 watthours. And so on. A 100 watt load could consist of a 12 volt appliance drawing 8.3 amperes or it might consist of a 120 volt appliance drawing .83 amperes. if the 120 volt, 100 watt unit is run for one hour it will consume .83 amperehours. And so on. Another unit of measure that you will come across is the kilowatt. A kilowatt is 1000 watts. A kilowatthour could result from a 100 watt load being powered for 10 hours or a 1000 watt load being powered for 1 hour. NOTE: the terms 170 volt, 117 volt and 120 voit, all refer to the same common household AC current. 6 Planning and Sizing a Solar Electric System in sizing a PV system the first two factors we work from are the sunlight levels or insolation values from your area and the daily power con- sumption of your electrical loads. Insotation Insolation or sunlight intensity is measured in equivaient full sun hours. One hour of maxi- mum, or 100% sunshine, received by a module equals one equivalent full sun hour. Even though the sun may pe above the horizon, for example, 14 hours a gay, this site may only receive six hours of equivalent full sun. Why? For two main rea- sons. One is reflection due to a high angie of the sun in relationship to your array. The second is also due to the high angle and the amount of the earth's atmosphere the light is passing through. When the sun is straight overhead the light is passing through the least amount of atmosphere. Sun Paths on December 21 and June 21 tor indianapolis ai, UNE 21 SUN PATH DECEMBEM 21 SUN PATH AT SUNSET This diagram illustrates the path of the sun over varying seasons. Remember when selecting a site for your solar modules to pick a spot that is clear of shade from a minimum of 10 A.M. to 2 P.M. on December 21st, Even a limb from a deciduous tree wiil substantially reduce power output. Early or fate in the day the sunfight is passing through much more of the atmosphere due to its position in tne sky. Our sun trackers can help reduce reflectance but cannot help with the increased atmosphere in the sun’s path. Because of these factors our most productive hours of suntight are from 9:00 a.m. to 3:00 p.m. around solar noon. Before and after these times we are making power but at much lower levels. When we size solar modules, we take these equivalent full sun hour figures per day and average them over a given period. See the charts below. We like to work with two figures here: aver- age annual equivalent full sun hours and average These are averages, contact us for your exact insolation data. Many solar sites are quite uncomplicated in terms of shading and aspect. You may already have a good idea of where the sun appears in the morning and disappears in the evening, as weil as how low it swings in the winter sky. if your site is partially Shaded, it may be necessary to determine exactly where the best placement of modules will be. We do have site analysis tools. if you need 4 more sophisticated site analysis, please contact us. We also have world-wide insolation data. winter equivalent full sun hours. In most locations in the United States winter yieids the least sunlight because of shorter days and increased cloud cover, as well as the sun’s lower position in the sky. The Basic Idea Is Simple Photovoltaic modules (solar panels) convert sunlight into electricity. “ire conducts the electricity to batteries where it is stored unt needed. On the way to the batteries, the electrical current passes through a controller (regulator) which will shut off the fiow when the batteries become full, For some appliances, electricity can be used directly from the batteries. This is “direct current” and it powers “DC” appliances such as car headlights, flashliahts, portable radios, etc. To run most appliances found in the home, however, we need to use “alternating current” or "AC", the type which is found in wati sockets. This we can produce utilizing an inverter which transtorms DC electricity from the batteries into AC. The inverter's AC output powers the circuit breaker box and the common outlets in your home. Soler irradionce Inverter Cantrotier Yearly average equivalent sun hours per day. Equivaient full sun hours per day for a four-week period from December 7th to January 4th. Calculating Power Consumption After determining the amount of solar radiation available, we must next determine the size of the load that we are supplying with power. The unit of measure for sizing is either watthours or amphours. We normally use watthours because it applies to both AC and DC circuits. The procedure is the same for all systems, regardiess of whether the load is a telecommunications re- peater or a house. What we need to end up with is a figure of the average daily watthours consumed. This will allow us to determine how many modules will be needed to produce the power and how many batteries will be needed to store the power. The table on this page is an analysis of energy usage for a representative small home. We have itemized each appliance and its individual run time per day and per week. We then summed the watt hours of all the individual units for a total daliy watt hour figure. Making up a chart such as this will allow you to understand where your power is going and may give you ideas for how to reduce your loads in the most effective manner. incorrectly assessing toads can end up being frustrating and expensive. Underestimating your loads can lead to major system inadequacies. Overestimat- ing will lead to excess capacity. While many of our hybrid systems have a range of flexibility in providing power, some systems do not. But both problems can be avoided by careful assessment of loads. Volts x Amperes = Watts Watts x Hours of Use = Watt hours YOU HAVE BEEN PROMOTED You are no longer just a consumer. You now manage your own power plant and enjoy the benefits and respon- sibilities entailed. It is critical that you know where your power is going. It is important that you compile the best information you can for the design process. It is impor- tant that you understand the basic elements of how your system functions. We are here as an information resource and as a backup should you need to troubleshoot a problem. You do not need to know all the electronic components that make up the internal workings of each controller or inverter. It is important that you are comfortable and knowiledgeabie with the day to day operation and mainte- nance requirements of your equipment, and that you rely upon yourself to ask us questions if there is something you do not understand. We cannot overemphasize the importance of putting together the most accurate information you can. Without it we are only guessing. A load evaluation form is included in the appendix for your use. Power Consumption Tables These figures are approximate representations. The actual power consumption of your appliances may vary substantiaily from these figures. Cneck the power tags, or better yet, measure the ampere draw with an amp meter, Multiply the hours used on tre average day oy the watts per hour listed below. This will give you the watt hours consumed per day, wnich you can then piug into the load calculation. We have approximated some of the duty cycle times (hours used eacn aay) for a theoretical average household. Actual use varies a great deal from house to nouse, and even seasonaiy within the same home. Remember that some items. sucn as garage door openers, are used only for a fraction of an hour or minute per day. A 300 watt item used for 5 minutes per day will oniy consume 25 watt hours per day. Where a range of numbers are given, the lower figure often denotes a technologically newer and more efficient model. The letters “NA” denote aoaliances which would normally be powered by non-electric sources in a PV powered nome. oe Appliance Watts/Hour Appliance Watts/Hour Appliance Watts/Hour Coffee pot 200 Garage door opener 350 Compact fluorescent Coffee maker 800 Ceiling fan 10-50 incandescent equivalents Toaster 800-1508 Table fan 10-25 40 watt equiv. 14 Popcorn papper 250 Electric Bianket 200 60 watt equiv. 16 Blender 300 Blow arver 1000 73 watt equiv. 20 Microwave 600-1566 Shaver 15 100 watt equiv. 30 Waffle iran 1200 Waterpik Hot plate 1200 Electric mower NA 1500 Frying pan 1200 Computer Hedge trimmer 450 laptop 20-50 Weed eater 500 Dishwasher 1200-150C pc 80-150 1/4" drill 250 Sink waste disposal 450 printer 100 1/2" drill 750 Typewriter 80-200 1" drill 1000 Washing machine TV 25" color 150 9” disc sander 1200 automatic 500 19" coior 70 3" belt sander 1000 Manual 300 12” baw 20 12" chain saw 1100 Vacuum cleaner VCR 40 14” band saw 1100 upriant 200-700 CD player 35 7 1/4" circ. saw 900 hand 100 Stereo 10-30 8 1/4" circ, saw 1400 Sewing machine 100 Clock raaio 4 Iron 1000 AM/FM car tape 8 Refrig/freezer - Conventional Satellite dish 30 20cf (15 hours) 540 Clothes dryer CB radio 5 T6cf (13) 475 electric NA 4000 Electric clock Sunfrost gas heated 300-400 16cf DC (7) 112 Radiotelepnone 12cf DC (7) 70 Heater receive Vestfrost refrigerator/freezer engine Diock NA “50-1000 transmit 10.5cf 60 portable NA 1500 Freezer - Conventional waterbed NA 400 Lights: 14cf ff (15) 440 stock tank NA 100 100w incandescent 100 14cf (14) 350 Furnace biower 300-1000 25w compact fluor. 28 sunfrost freezer Air conditioner NA SOw DC incandescent 50 19cf (10) V2 room 1000 40w OC halogen 40 Vestfrost refrigerator/freezer centrai 2000-5000 20w DC compact fluor. 22 7.5ch(8) 30 rr pS We strongly suggest that you invest in a multimeter if you are considering making your own power. Also helpful are clamp-on type amp-meters. it actually makes sense to know where your power is being used, even if you are not producing it, and if you are, these meters are essential diagnostic tools. a a a nn ee 1. Does it really ‘cost more:to:pur- chase a. generator that-requires:no:. i refueling for:20:t0:30' years:or: more, needs:no maintenance-and:is’as®: environmentally: benign:as:a window i In-your-home?.° poy Our customers: have-invested in PV: | for a diversity of:teasons:economics. : of: producing: power:in: remote foca- | tions; security of:horne-power:sup-~ plies; taking:a. personal:stand:on= environmentally threatening: issues; or just to:get:away- from ‘the:noiseand « inefficiency’ of: e mater generat Your Electrical Inspector and PV We have found that some electrical inspectors are not familiar with photovoltaics and the section of the National Electrical Code which deals with it. For this reason we find it generally best for the system owner to communicate with your inspector early on in the process. You can install the system first and ask questions second, but the possibility of inconvenient and costly changes is very reai. While we recommend following national code where applicable, local codes may vary; your inspector can tell you how they differ. Please remember that it is the inspector's job to keep your wiring safe, now and for the future. AC or DC The AC versus DC debate goes back to at feast the time of Mr. Edison and Mr. Westinghouse. High voltage AC has the advantage of being efficientiy conducted over very long distances with relatively iow transmission iosses. AC has thus become the standard for industry and domestic usage. DC is generaily used in iow voltages, where trans- mission efficiencies are low. In some cases however, DC does have the advantage of efficiency in operation; as much as twice that of AC for some applications. A disadvantage of DC is that many appliances and equip- ment in 12 Volt DC versions are hard to find and are expensive. ; Both have their advantages. With water pumping systems, we generally use all DC. In home systems we typically run ail or the majority of loads with AC power. For maximum efficiency certain specific loads can easily be powered by OC circuits. Cabins or RV's use mostly DC and can use regular gauge wire because of small loads and short transmission distances. How much room will the: system require? For a home system, a heated room in the utility area or near the circuit breaker box is normally utilized. The batteries are contained in an enclosure vented to the outside perhaps the size of a washing machine or, in a larger home, the size of a chest freezer. Controllers, meters and inverters are generally mounted on the wail in a space a couple feet square and may project out one foot. Outside, the space required is dependent on the number of modules. A space the size of two or three 4X8 sheets of plywood will accommodate a medium household system. Another option is to utilize a separate power house. This offers a safe, convenient space for electrical components, the genera- tor and possibly the mounting of the solar array. ie This powerhouse is a locally made mini-barn, now fully insulated. The solar electric fence protects arrays, gen-shed, water storage tank : and well area from livestock damage. _ PERSE PROSE OEE PSNR TIE Zoe AER ES Rd 10 The Importance of High Efficiency Using the best available technologies can save you money by saving energy. Such appliances often provide better service than outdated and inefficient technologies. These newer designs often cost more initially than their cruder counterparts but can have impressively short payback times. The importance of high efficiency appliances becomes doubly important for someone providing their own electricity. For example: a high efficiency refrigerator might be run with three 80 watt PV modules where as a conventional refrigerator might necessitate an additional 9 modules and additional battery capacity. This extra generating and storage capacity will cost many times the investment of the more efficient unit. An additional benefit is that more efficiency means less run time and less wear and tear on components. In the case of the refrigera- tor this can mean a life span twice that of the conventional unit. Ghost Loads Smail loads that are not easily discernible but can consume considerable amounts of power each day are termed “ghost loads”. Examples include “instant on" circuitry in a television, wall cube transformers for answering machines, and electronic typewriters. These types of loads can sneak far more than their fair share of power. If not anticipated, located and dealt with, ghost loads can waste a substantia! quantity of power. “Power cubes” or “wall cubes” that plug into Outlets to convert AC to DC for electronic equipment contain small transformers which can waste incredible amounts of power. A unit for a boom box, for instance, might consume 17 watts of power 24 hours a day, even though the actual device uses only 7 waits. These kinds of loads are difficult to detect with an AC amp meter. The best way to find them is to shut every load in the home “off”, and then shut down ail circuits at the breaker box. Using a DC amp meter on the main battery cable, monitor each circuit as they are turned on one by one. if there is a ghost, it will appear. There are two ways to deal with these trouble- some loads. The first, easiest, and most costly method is to accept them. Accept the fact that your inverter will never go into standby mode, add on to your array to compensate for this power consumption. c 2 a E 3 w ec 3 u - 5 A o = oi ra) gerator ating | Refrigerator Solar or Wood Heating, Conventional Incandescents Conventiona Cooking, Water Heating High Efficiency Lights and Refri Gas, Gas or Solar or Wood Cooking, Water Heating and Space He Representative Households The second method minimizes power consump- tion. Place switches on the appliances that run unnecessarily, turning them truly off and on when required. For small, but necessary, loads -— consider operating these at 12 or 24 volts DC. If this is not possible, a second, smaller, inverter can be installed to run select loads more efficiently. By doing this, the inverter can return to a no-load or idle mode, where it uses very little power. Common Appliances with Ghost Loads TV's and VCR's Electric clocks Clocks built in to appliances (microwaves, ranges, telephones) Ni-Cad Battery chargers Ground Fault Interrupting Receptacles and breakers (GFCI) Cordless telephones Answering machines Low voltage appliances that can also utilize AC power = System Components _11 System Components Systems vary greatly due to variation in size and run times of differing loads. They can use as little as a single 5 watt module or hunareds of large modules. There really is no such thing as an “average” system, even within a single kind of use. However, the basic PV system can be divided into several major components. The following section tists these components and their functions. Components of a Solar Electric System Component Function Modules Generates electricity from suntight Controller Regulates power to and from batteries Fusing/Breakers Overcurrent protection and Disconnects Combiner Box Enclosure for paralleling module output Batteries Stores electricity Monitors Reports system status and power flows and meters both instantaneously and cumulatively. Component Inverter Generator Battery charger Fixed Mount or Tracking Mount Powercenter Function Changes low voltage DC power to high voitage AC power Provides backup AC power Converts AC (generator power) to DC Supports and aims modules toward sun Combines: controllers, overcurrent protection and monitors in one enciosure System Voitage Selection 12, 24 or 48 volts? The nominal voitage of your system is usually determined by the system size. Small to medium systems, where most loads are DC, or a few loads are AC through an inverter, lend themselves to 12 voits nicely. Many lights and smail appliances can be found at this voltage and efficiencies are high. On the down side, 12 voit suffers from high line loss problems. The solar modules and loads cannot be far from the battery bank. (Review the wire loss tables in the Appendix.) 24 volt systems are suggested for medium to large systems. With 24 volts we nave less wire loss oroblems and larger inverters are available. 24 volt DC appliances are more rare than 12 volt units. For this reason we lean heavily toward AC loads from these jarger inverters. This simplifies wiring of the home to conventional AC wiring which exists in most nomes and which any electrician can wire economically. With the increased efficiency of AC lighting and the uniimited variety of low cost AC appliances, 24 voit systems, as weil as 48 for large systems, have many advantages. 12 a Solar Modules Power Characteristics The current and power output of photovoltaic modules are approximately proportional to sunlight intensity. At a given intensity, a module’s output current and operating voltage are determined by the characteristics of the load. If that toad is a battery, the battery's internal resistance will dictate the module's operating voltage. A module which is rated at 17 volts will put Out less than its rated power when used in a battery system. This is because the working voltage will be between 12 and 15 volts. As wattage (power) is the product of volts times amps, the module output will be reduced, For example: a SO watt module working at 13.0 volts will produce 39.0 watts (13.0 volts x 3.0 amps = 39.0 watts). This is important to remember when sizing a PY system. An |-V curve as illustrated to the right fs simply all of a module's possibie operating points (voltage/ current combinations) at a given cell temperature and light intensity. Increases in cell temperature increase current but decrease voltage. Maximum power is derived at the knee of the curve. Check the amperage generated at your batteries operating voltages to better illustrate the actual power developed at your voltages and temperatures. Te er} Mixing Sizes and Brands of Modules IN most cases mixing dissimilar modules in the same array is not a problem. When paralleling units of different amperage ratings, the output of the array will simply be the sum of the combined amperages. When paralleling units of different voltages, the lower voltage units wiil simply begin to taper off sooner as high battery voltage is reached. If used for array direct power, the array voltage will be the approximate average module voltage. When series connecting strings of dissimilar modules, however, the amperage will be approximately that of the weakest module in the string. It pays then, to pay attention to matching the modules connected in series. nN tn = = 20 2 = a —_ wn Shading PV modules are very sensitive to shading. Unlike a solar thermai panei which can tolerate some shading, many brands of PV modules cannot even be shaded by the branch of a leafless tree. Once a solar cell or a portion of a ceil is shaded it becomes a load and draws power instead of producing it. Watch the amp meter of your system when a hand is passed over a module and you will see a substantia! drop in output. Some solar modules offer protection from partial shading. The advanced design of these modules include a diode between every cell, reducing partial shading problems. Ask your solar professionals for more information if shade protection is needed. Another rule of thumb - make sure no shading occurs between 9:00 a.m. and 3:00 p.m. around solar noon. Shading early or late is not much of a problem because these are low power producing hours anyway. Reverse current protection PV modules wiil leak power back from your batteries during no sun periods if not protected. This leakage is very smalt but over long, no-sun periods, this lass can accumulate. To prevent this we install a diode or protecting circuitry in the controller. All controtlers that we sefl have reverse leakage protec- tion. The circuit opens over periods of no sun, allowing the charging circuit to stop any reverse flow. A diode can also be used. This unit acts as a one way check vaive-ietting power flow in one direction to the batteries but not back to the PV module. Module Mounting Solar modules perform best when perpendicu- iar to the sun's rays. Because tracking the sun is not always possible, we typically mount the modules facing due south. A common question is the effectiveness of facing one module to the southeast, one due south and another southwest. While this may sound iike a good idea, it is not. All modules facing due soutn will net the largest amount of power of any other arrange ment second only to a sun tracker. Rememper that the true south and magnetic south vary upon your site's declination. Call your iocal airport or us if you do not have this figure. Tilt angle Because the sun's position in the sky varies through the year (higher in summer and tower in winter), it's a good idea to provide for seasonal adjustment. The rule of thumb goes: latituae plus 15 Gegrees angie in winter and latitude minus 15 degrees in summer. Your latitude can be found on any good map of your area. If you wish to permanently mount the modules .and not seasonally adjust the structure, fix your mount at a winter (minimal sun period) angie. This is when suntight is limited, days are shorter and you want the system maximizing the available power. We offer a wide variety of mounts both fixed and tracking. To Track the Sun... or Not To Track... Trackers are used to increase the daily output of PV modules by keeping them faced as directly as possible toward the sun. The sun sees a wider surface, and the increased reflectivity that occurs at low angles of incidence is avoided. During the long days of summer when the sun is rising north of east and setting north of west, a tracker can increase the daily output of modules by 25 to 40 percent (we can heip determine what you can expect). During the winter when the sun takes a low, short arc above the horizon, the tracker will contribute much less, perhaps 10 to 15 percent. The output of a tracker remains much more constant througnout the year in tropical climates. We generally recommend trackers for soring, summer and fali applications, such as water pumping for iivestock summer pasture or small scale irrigation. For home power systems, we often do not recommend them because a household's power requirements are generally greatest in the winter just when the efficiency of the tracker is least. It often is a better choice to use a less expensive static mount and put the money into extra modules. In tropical and subtropical regions with less seasonal variation of sun and loads a tracker can make sense tor a home system. When calculating aiming error, rule of thumb is that a 10 degree aiming error will resuit in a loss of 2% of the solar module output, 20 degree-6%, 30 degree-14%, 40 degree-22%, 50 degree-35%, 60 degree-50%. This table betow compares insolation for fixed and tracking surfaces at three U.S. cities of varying iatitudes. We have data for many locations broken down by the month, cail if you wouid like the figures for your area. Fixed Array Summer position latitude -15 deg. Winter position Albuquerque, NM January 4.49 July 7.78 Pittsburgh, PA January 2.02 July 5.59 Great Falls, MT January 2.51 July 7.62 Values are equivalent full sun hours per day. latitude +15 deg. Fixed A One Axis Tracki one Ailes Track Two Axis Tracki Summer Winter latitude -15 deg. latitude +15 deg E&Ww, N&S 14 ene ee SSNS Wind Driven Generators An excellent complement to any battery system Is Wind Generation for you? Electricity produced by wind generation can be used directly, as in water pumping applications, or it can be stored in batteries for household usage. Wind generators can be used alone, or they may be used as part of a hybrid system, in which their output is combined with that of photovoltaics, and/or a fossil fuel generator. Hybrid systems are especially useful for winter backup of home systems where cloudy weather and windy conditions occur simultaneously. The most important decision when considering wind power is determining whether or not your chosen site has enough wind to generate the power for your needs, whether it is available consistently, and if it is available in the season that you need it. The power available from the wind varies as the cube of the wind speed. If the wind speed doubles, the power of the wind (the ability to do work) increases 8 times. For example, a 10 mile per hour wind has one eighth the power of a 20 mile per hour wind. (10 x 10 x 10 = 1000 versus 20 x 20 x 20 = 8000). GATTERIES (N VENTED ENCLOSURE INVERTER (patent pending) \ One of the effects of the cube rule is that a site which has an average wind speed reflecting wide swings from very low to very high veiocity may have twice or more the energy potential of a site with the same average wind speed which experiences little variation. This is because the occasionai high wind packs a lot of power into a short period of time. Of course, it is important that this occasional high wind come often enough to keep your batteries charged. If you are trying to provide smaller amounts of power consistently, you should use a generator that operates effectively at slower wind velocities. Wind speed data is often avaiiable from local weather stations or airports, as weil as the US Dept. of Commerce, National Climatic Center in Asheville, N.C. You can also do your own site analysis with an anemometer or totalizer and careful observation. Installation of generators shoutd be close to the battery bank to minimize line loss, and 20 feet higher than obstructions within 500 feet. The tower should be well grounded. 15 Charge Controllers/Regulators Why you need a controller The main function of a controiler or reguiator is to fully charge a battery without permitting overcharge. If a solar array is connected to iead acid batteries with no overcharge protection, battery life will be compromised. Simple controllers contain a relay that opens the charging circuit, terminating the charge at a pre-set high voitage and, once a pre-set low voltage is reached, clases the circuit, allowing charging to continue. More sophisticated controlters have several stages and charging sequences to assure the battery is being fully charged. The first 70% to 80% of battery capacity is easily replaced. It is the last 20% to 30% that requires more attention and therefore more complexity. How Controllers Work and Available Options The circuitry in a controller reads the voltage of the batteries to determine the state of charge. Designs and circuits vary, but most controliers read voltage to reduce the amount of power flowing into the battery as the battery nears full charge. Features that can be included with controllers include: + Reverse current leakage protection- by disconnecting the array or using a blocking diode to prevent current loss into the solar modules at night. - Low-voltage load disconnect (LVD)- to reduce damage to batteries by avoiding deep discharge. + System monitoring- analog or digital meters, indicator lights and/or warning alarms. » Overcurrent protection- with fuses and/or circuit breakers + Mounting options- flush mounting, wall mounting, indoor or outdoor enclosures - System control- contro! of other components in the system; standby generator or auxiliary charging system, diverting array power once batteries are charged, transfer to secondary batteries. + Load control- automatic control of secondary loads, or controi of fights, water pumps or other loads with timers or switches + Temperature compensation - utilized whenever batteries are placed in a non-climate controlled space. The charging voltage is adjusted to the temperature. Recommended on most systems. + Central wiring: providing terminals to interconnect system wiring. Some systems require all of these functions, others require only one or a certain combination. We can heip you select a unit to meet your specific needs. Sizing a Controller Charge controliers are rated and sized to the systems they protect by the array current and voltage. Most common are 12, 24 and 48 voit controilers. Amperage ratings run from 1 amp to over 100. For example, if one module in your 12 volt system produces 3.5 amps and four modules are utilized, we produce 14 amps of current at 12 volts. Because of light reflection and the edge of cloud effect, sporadically increased current jevels are not uncommon. for this reason we increase the controller amperage by a minimum of 25% bringing our minimum controller amperage to 18.7. Looking through the products we find a 20 amp controller, as close a match as possible. There is no problem with going to a 30 amp or larger controlier, besides possible additional cost. if you think the system may increase in size, additional amperage capacity at this time should be considered. On smail systems where a 10 watt or smaller module charges 100 amp hour battery or larger, no regulator is required. Typically this module to battery ratio cannot overcharge the battery. Will a controller be included in my powercenter? Yes, all powercenters include a solar charge controller. in fact, if you are duilding a system that utilizes an inverter, we recommend looking strongly at utilizing a powercenter. Why? Simply because they are typically more reliable, save time and money. The controller, array and battery disconnects, monitoring and central wiring can all be handied with one enclosure instead of five or more. Pump or Motor Controllers Different than the above battery charge controlier, these units work in systems that directly link the solar module to a motor, no battery storage is utilized. These controliers alter the incoming amperage and voltage to what is required by the motor. In tow light conditions, modules produce tittle current yet reiatively constant voltage. These motor controilers will reduce the voltage to increase the amperage, starting and running Some owners prefer to purchase their system compo- nent by component, and others would rather buy the carburetor with the rest of the vehicle. Whatever your personal preference, we would like to work with you. the motor in jow light. The effect is an increased motor run time throughout the day, moving more air or water in a day than an array direct system with no controlier. 16 INVERTERS - Introduction The inverter is a basic component on medium to large replacea with gas appliances, there is tittle need for 240 systems which converts low voltage DC power from the VAC power. Exceptions include good-sized submersible -batteries into high voltage (usually 120 or 240) AC power pumps and shop tools which can either be powered by the as needed. generator, step-up transformer, or possibly justify the cost inverters of the past were inefficient and unreliable. of a larger or second inverter. Today's generation of inverters are very efficient (85 to Two types of inverters predominate the market ~ 94%) and very reliable. modified sine and sinewave inverters. Today, the majority, if not ail cf the loads in a typical Modified sinewave units are less expensive per watt of remote home operate at 120 VAC from the inverter. The power and do a good job of operating all but the most only reason to operate select loaas at low voitage DC isto | delicate appliances. Sinewave units produce power which is maximize efficiency. almost identical to the utitity grid, will operate any appli- Most inverters we sell produce only 120 VAC, not ance within their power range, and cost more per watt of 120/240 VAC as in the typicai utility-connected home. The output. reason being, once electrical heating appliances are Inverter Component Checklist While an inverter is a good portion of the cost of a system, it is really a sub-system that includes a number of additional components. To make a Safe, reliabie installation one should provide the following: Inverter to battery cabling. Because of the high current Shunts - Used to read the amperage flowing between the required on low voltage circuits, this cable is large, battery and inverter, this device is installed in the negative commoniy #2 to 4/0 in size. Smaller conductors than conductor. it can easily be housed in the disconnect or its required are unsafe and will not allow the inverter to own enclosure. perform to its full rating. AC output disconnect and overcurrent protection. if DC input disconnect and overcurrent protection. It is the breaker panel, which is fed from the inverter, is important to have a safe installation with a properly sized adjacent to the inverter, then the main breaker will serve DC rated, UL listed disconnect. Typically the disconnect as the inverter output disconnect and overcurrent protec- works in conjunction with a overcurrent protection device tion. lf, however, this panel is not grouped with the such as a fuse or breaker. These components are installed inverter, then a separate unit should be installed. This aiso in an enclosure which can also house shunts. holds true with AC circuits coming to the inverter from a generator or utility source. A second breaker may be needed if these breakers are not grouped. See the Sizing Tables in the Appendix for cable and overcurrent device sizing for the inverter you select. oc DISCONNECT INVERTER BREAKER TO AC HOUSE e_4 PANEL FUSING AND SHUNTS INVERTER ws QUal SATTERY Commer GENFRATOR BREAKER FROM GENERATOR [weed Sactia le) 2 vant © Ad kegs Mees oe inverter Sub-system Checklist Inverter to Battery Cabling DC disconnect and overcurrent device ______. Inverter conduit boxes inverter output breaker box Generator input breaker box | BATTERIES IN VENTED ENCLOSURE i Shunt(s) if required for monitoring f | 17 Inverters with Built-In Battery Chargers Many of today's inverters incorporate battery charging circuitry. This is easily and economically accomplished because of the design of most inverters. Inverters step up low voltage and change DC power to AC power. Battery chargers do the reverse of this. Additional circuitry is all that is required to add a whole second function and economically create an inverter/Charger. Transfer switches are also incorporated into these Inverter/Chargers so that the AC loads can be powered directly from the generator when the battery charger is operating. From a reliability, performance, and economical standpoint, built-in battery chargers are the way to go. Comparing Inverters Inverters are compared by three factors: + Continuous wattage rating. Hour after hour, what amount of power in watts can the inverter deliver. + Surge Power. How much power and for how long can an inverter deliver the power needed to start motors and other loads. + Efficiency. How efficient is the inverter at low, medium and high power draws. How much power is used at idle. Multi-stage Battery Charging A typical 12 volt lead-acid battery must be taken to approximately 14.2-14.4 VDC before it is fully charged. (For 24 volt systems double these figures.) If taken to a lesser voltage level, some of the sulfate deposits that form during discharge wili remain on the plates. Over time, these deposits will cause a 200 amp-hour battery to act more like a 100 amp-hour battery, and battery life will be considerably shortened. Once fuily charged, batteries should be held at a considerably lower voltage to maintain their charge - typically 13.2 to 13.4 volts. Higher voltage Jevels will "gas" the battery and boil off electrolyte, again shortening battery life. Most battery charger designs cannot deai with the conflicting voltage requirements of the initiat "bulk charge" and sudsequent “float” or maintenance stage. These designs can accommodate only one charge voltage, and therefore must use &@ compromise setting - typicaily 13.8 volts. The result is a slow incomplete charge, sulfate deposit build-up, excessive gassing and reduced battery life. The charger available tn our inverters automatically cycles batteries through a proper muiti-stage sequence to assure a rapid and complete charge without excessive gassing. Factory battery charger settings on our inverter-charger combinations are optimal for a lead acid (liquid electrolyte) battery bank of 250-300 amp hours in a 60° F environment. !f your installation varies from these conditions, you will 15 TECH MATHSTAGE Ww . BATTERY CHARGER g (CONSTANT VOLTAGE) —_ 14 *wEKAVOG al - > ee © ee 3 Se A > fe OD PLOATAAAINTENANCE a 13 ca A TANT VOLTAGE: 29th VOC}= Lu is 2 E ff TYPICAL BATTERY CHARGER a " N * TIME > obtain better performance from your batteries if you adjust the control settings. The Maximum Charge Rate in amps should be set to 20- 25% of the total amp-hour rating of a liquid electrolyte battery bank. For example, a 400 amp-hour bank should be charged at no more than a 80-100 amp rate. Excessive charge rates can damage batteries and create a safety hazard. The Bulk Charge Voltage of typical liquid electrolyte batteries should be about 14.4 VDC; gel cells like the Deka about 14.1 VDC. There is no one correct voltage for all types of batteries. incorrect voltages will limit battery performance and useful life. Check your battery maker's recommendations. The Return Amps setting controls how long the batteries will be heid at the bulk charge voltage before dropping to the float/maintenance level. A good setting is 2-4% of the amp hour capacity of a liquid electrolyte battery bank. A fixed, “one-size-fits-all” setting will overcharge a large battery bank (gassing the batteries) and undercharge a small bank {limiting battery performance). The Float Voltage setting should hold the batteries at a Jevel high enough to maintain a full charge, but not so high as to cause excessive “gassing” which wiil “boil off" electro- lyte. For a 12 volt liquid electrolyte battery at rest, a float voltage of 13.2-13.4 is normally appropriate; gel cells are typically maintained between 13.5 and 13.8. If the batteries are being used while in the float stage, slightly higher settings may be required. Charge voltage guidelines used here are based on ambient temperatures of 60° F. If your batteries are not in a 60° F environment, the guidelines are not valid. Temperature Compensation allows easy single dial re-scaile of the voltage settings to compensate for the differences between ambient temperature and the 60° F baseline. Temperature compensa- tion is important for ail battery types, but particularly gel cell, vaive-reguiated types wnich are more sensitive to temperature. > 18 Batteries - The Heart of the System A Solar Electric system is made up of a number of components, ana of these, none needs as much attention as the batteries. Thougn the idea ana usage of a battery bank is very simple, if batteries are neglected, degradation can occur at a fast pace. As someone in the industry once put it, “few batteries die a natural death, most are murdered”. The follow- ing information is designed to tell you how to get the longest life possible from your battery bank. (This is strictly flooded cell tead-acid battery information; for Alkaline and gei-cell batteries many of these needs and characteristics are completely different.) Cycling - Deep versus Shailow A cycle in the battery world occurs when you discharge a battery and then charge the battery back again to the same level. The battery is designed to absorb and give up electricity by a reversible electrochemical reaction. How deep a battery is discharged is termed depth of discharge. A shallow cycle occurs when the top 20% or less of the battery's power is dischargea and then recharged. Some batteries, like automotive starting batteries, are designed for this type of cycling only. The plates of active material are thin with large overall surface area. This design can give up lots of power in a very short time. The second type of cycle is a deep cycle where up to 80% of the battery capacity is discharged and recharged. Batteries designed for deep cycling are built with thicker plates of active material which have less overall surface area. Because of the jessened availability of surface area for cnemical reaction, these batteries yield just as much power relative to their size, but do so over a longer period of time. This type of battery design is preferred for a PV system because discharging a battery to a deeper level is normai during extended cloudy weather. The depth of cycling has a good deal to do with determining a battery's useful life. Even batteries designed for deep cycling are “used up” faster as the depth of discharge ts increased. It is common practice for a system to be designed with deep cycle batteries even though the daily or average discharging amounts to a relatively shailow depth of dis- charge. Shallow cycte your deep cycle battery for the most cycies. Temperature Effects The speed of the chemical reaction occurring in a lead-acid battery is determined by temperature. The colder the temperature the slower the reaction. The warmer the temperature the faster the reaction and the more quickly the charge can be drawn from the battery. The optimum operating temperature for a lead-acid battery is around 77 degrees Fahrenheit. You may have expert enced this effect when starting a car on a cold morning; the engine just doesn’t turn over as quickly. Warm that same battery and you will see a major improvement. (See the oar graph of temperature effects to the left and the temperature derating quidelines in the battery sizing worksheet in the Appendix.) For this reason we like to see batteries placed indoors or in a heated and ventilated space to maintain them between 55 and 80 degrees. if we do install them in a unheated space, battery capacity must be increased to compensate for this derating. High temperatures can drastically shorten the life of the battery and should be avoided. Comparison of short term power available from fully charged battery at various temperatures 19 —————————— Batteries - continued Self Discharge Due to impurities in the chemicals used for battery construction, batteries will tose power to locai action, an internal reaction which occurs whether we are using the battery or not. This slow discharging ‘s termed self-discharge. Self-discharge rates vary greatly among battery types and varies with temperature. The rate also increases with the age of a battery, so much so that an old battery may require a significant amount of charging just to stay even. Even new batteries may lose 1 to 2% of charge per day. Lead calcium grid batteries have the lowest self- discharge rates. Battery Power Conversion Efficiency Energy is never consumed or produced, it merely changes form. The efficiency of conversion is never 100% and in the case of new batteries ranges from 80 to 90%. This means that to discharge 100 watts of power from a battery !t must be charged with 110 to 120 watts of power. Percentage 12 volt 24 volt of Battery Battery Specific Charge Voltage Voltage Gravity 100 12.70 25.40 1.265 95 12.64 25.25 1.257 90 12.58 25.16 1.249 85 12.52 25,04 1.241 80 12.46 24.92 1.233 75 12.40 24.80 1.225 70 2.36 24.72 4.218 65 42.32 24.64 1.211 60 12.28 24,56 1.204 35 12.24 24.48 1.197 50 12.20 24.40 1.190 45 12.16 24.32 1.183 40 12.12 24.24 1.176 35 12.08 24.16 1.169 30 12.04 24.08 1.162 25 12.00 24.00 1.155 20 11.98 23.96 1.148 15 11.96 23.92 1.141 10 41.94 23.88 1.134 3 41.92 23.84 1.127 Discharged ‘1.90 23.80 1.120 Specific gravity values can vary + or ~.015 points of the specified values. This table is for the Trojan L-16 battery in a Static condition, no charging or discharging occurring, at 77 degrees F. Discharging or charging wiil vary these voltages substantially. Source - Trojan Battery Company. Determining Battery State of Charge Battery state of charge is determined by reading either terminal voltage or the specific gravity of the electrolyte. The density or specific gravity of the sulfuric acid electrolyte of a lead-acid battery varies with the state of charge. The density is lower when the battery is discharged and higher as the cells are charged. See the table to the left; this is because the electrolyte is part of the chemical reaction, it changes as the chemical reaction takes piace. Specific gravity is read with a hydrometer. A hydrometer reading will tell the exact state of charge. A hydrometer cannot be used with sealed or gel-cell batteries. Another important point is freezing. At low densities, the electro- lyte contains enough water that the battery can freeze. This is not a problem with PV systems where the batteries are kept both warm and chargea. Batteries can survive and operate in a cold location, but the charge tevel should not be so low that it could freeze. Battery Voltage Voltage meters are used to indicate battery state of charge. They are relatively inexpensive and easy to use. The main problem with relying on voltage reading is the high degree of battery voitage variation through the working day. Battery voltage reacts highly to charging and discharging. In a PV system we are usuaily charging or discharging and many times are doing both at the same time. As a battery is charged the indicated voltage increases and as discharging occurs. the indicated voltage decreases. These variations may seem hard to track, yet in reality they are not. A good accurate digital meter with a tenth of a volt calibration can be used with success. The pushing and pulling of voltage, once accounted for by experience, can also help indicate the amount of charging or is taki lace. discharging that is taking pla (continued on next page) 20 Batteries - continued By comparing voltage readings to hydrometer readings and shutting off various charging sources and loads and watching the resulting voitage changes, the system owner can learn to use indicatea voltage readings with good results. Monitoring and Maintenance Monitoring battery state of charge is the single largest responsibility of the system owner. The battery voltage should be kept at or above a 50% state of charge for maximum battery life. See the battery voltage table. Keep the battery's electrolyte level to the indicated ‘evel and never let the plates be exposed above the alectrolyte. Use only distilled water - "ot tap water, wnen refilling the batteries. Water is the only element used by your battery. You should never have to add acid to your battery. Do not over-fill the batteries or fill when the batteries are discharged. Over-watering dilutes the acid excessively and electrolyte will be expe:led when charging. Gassing As batteries are charged they create bubbles of gas, oroduced when the chemical reaction can not keep up with the energy input. Some gassing 1s necessary in flooded cell batteries. The amount and duration of gassing varies fram one battery to another. Gassing mixes the electrolyte and compensates for the tendency of the acid to stratify with the most dense electroiyte on the bottom. Gassing is the proauct of splitting water molecules into hydrogen and oxygen. This consumes water ana creates the need for its periodic replacement. “Cold cranking amps” is not a usable measure of total amper- age capacity of a deep cycle battery. it instead measures the high rate (30 seconds) dis- charge ability of a battery at zero degrees Fahrenheit. For almost all photovoitaic systems, these conditions are very abnormal. Corrosion A slight acid mist Is formed as the electrolyte bubbles upon charging. This mist is nighly corrosive, especially to the metallic connectors on tne tops of the batteries. Inspect for corrosion and clean these periodically as needed with baking soda ana water. Corrosion buildup can create a good deal of electrical resistance, which can contribute to shortened battery life and the waste of power, It's always a good idea to wear goggies and orotective gear as the sulfuric acid will eat holes in your clothes. Equalization Equalization is the controtled overcharg- ing of a fully charged battery. This over- charge mixes the electrolyte, evens the charge among varying battery cells and’ reduces permanent suifation of the battery plates. It is energy invested in lengthening the life of the battery. Though the PV system battery bank receives a good deal of cycling and gassing through normal activity, we believe that equalization is a comple- ment to this activity and as a rule of thumb should be done every 60 to 90 days. The equalization process consumes water and produces much gassing. Make sure your batteries are weil ventilated during this charging. Equalization charging voltages vary widely, as do duration times, so the batteries should be monitored closely during this process. Check specific gravities of ail your cells at the start, noting any low cells. Check periodically during the process. You don’t have to check every cell each time, but watch any that show a higher variation. Keep checking electrolyte densities until you receive three readings of 30 minutes apart which indicate no further increase of specific gravity values, Keep a record of individual ceil voltages and specific gravities before and after equalizing. Equalization will take your voltage to 15 volts or higher (30 volts on a 24 voit system) so make sure any DC loads are disconnected before you begin. Battery Connections The connections from battery to battery and on to the charging and load circuits are critical. Terminals should be greased, interconnects should be clean and fastening hardware should be tight. Torquing ail bolts equally avoids variations in resistance. This is also the reason we prefer to minimize the number of parailel strings in the bank. Higher resistance values on one string of batteries results in fess charge to that string and consequently shorter life. We also place the main negative and positive on opposing corners of the battery bank for this reason. The goal is to keep the variation of resistance from one cell to another to a minimum. 21 Battery Enclosures Install your batteries in a warm, cry location. 55-80 degrees F. ‘s the optimum temperature range; jower or nigher than this and performance diminishes significantly. Because batteries produce a potentaily explosive mixture of hyaro- gen and oxygen, venting is needed to prevent a buildup. Since hyarogen is lighter than air it has a tendency to rise. {f venting is placed at tne top of the battery enclosure and air is brought in from the bottom, this gas will move up and out of the battery area. When possible, power VENT venting of the battery enciosure to the outside is a wise move. w Also remember that most basements will draw air, not expel air, if not power vented. Pre-built battery enclosures are used in remote lighting systems or anywhere a battery bank is installed wnere protection from tampering and weather is required. Large home battery bank enclosures are typically custom built. Banks of one to four batteries for water pumps, automatic lighting, telemetry or radio equipment are often installed in one of our off-the-shelf enclosures. These enclosures can be mounted on OUTSIDE ———| HEAVILY INSULATED TOP 2-YOLT CELLS INSULATED WALLS the ground or up on a pole behind the array to provide a higher aegree of protection from vandals. Another option here is to place the batteries out-of-doors in a heated outbuilding. You can also place the batteries on the outside of an exterior wail with the control and power conditioning directly through the wall indoors. Keeping the batteries simultaneousiy warm and adequately vented can be challenging, yet with proper planning is not that aifficult. Appropriate Number of Cycles Overcurrent Protection Amp Hrs. of to 80% Depth Capacity Discharge Batteries have the potential to discharge incredible ; amounts of power over a very short period of time, melting mubomonie te Yor elan conductors aise possibly starting a fire. eM manne = a2 vou 100 This is why we spend so much time and energy on Golf cart - 6 volt 220 overcurrent protection. it is not so much the PV module that Mining Vehicle - 6 voit 350 we need to protect against, but the batteries. PV modules 2 voit industrial cells 100-1500 are current limited which reduces the danger, yet modules and their conductors also require protection. The idea of a fuse or breaker is to include a "weak link" in each circuit which will open if the current exceeds that which the conductor can safely handle. in a typical PV system, we deal with both AC and DC power. Standard components purchased at building supply stores are typically rated for AC use. These are fine for inverter output circuit protection. Used Batteries Used lead acid batteries, especially large two volt telephone type cells can sometimes be found for sale. While used solar modules and inverters are usually an acceptable risk, used DC overcurrent devices required between the battery, batteries are a high risk proposition. Should you inverter, controller and modules are much more specialized. consider them? In our experience, it is difficult They are generally heavier duty and more costly. to know just how an older battery has been Of primary importance is to place a current limiting fuse used. Has the previous user taken good care of and disconnect on the main battery conductor and assure the ceils or have they been negiected? Have that ail components on the OC side are rated for DC use. they actually been toad tested or just cleaned If you are installing your own system, please obtain a up and recharged? Our recommenaation is to copy of the National Electric Code, work with your inspector get as much information as you can on the and be safe. We offer and suggest the publication, "PV cells, and load test them, or ask the seller for a Power Systems and the N.E.C. Suggested Practices,” free to ioad test. Without this test your are really anyone who is interested. guessing as to the remaining life. lf you are considering telephone cells, realize that they are normally shallow cycle lead calcium grid construction, and should not be used in a system designed for deep cycle use. 22 MONITORS Proper monitoring of a system should not be overlooked. Typically we want to know now much power is coming into the system from its charging sources and the state of charge of the battery bank at any point in time. A third and equally impor- tant value is how much power is being used by the systems loads. Smail systems usually monitor state of charge, or battery voltage and possibly incoming amperage. Medium and larger sized systems typically require a measure- ment of outgoing power as well, so one can keep track and not over discharge the battery bank. Shunts What is a shunt? A shunt IS a device used to measure large DC current, typically the current flowing to and from your battery bank. In more detail a shunt is a precision resistor which pro- duces a very accurate voltage drop when current is passed through the unit. This voltage drop is proportional to the amount of amperage flow, therefore by reading the millivoltage one can observe current flow on a properly calibrated meter. Do you need a shunt? Depending upon the monitor you select, you may! Smail meters with low currents may contain their own shunt, usually those iess than 30 amps. Larger and more complex monitors usually require an external shunt. While some units include a shunt, some do not. Where is a shunt installed? In the main negative conductor from the battery bank. The shunt is placed close to the battery, bank, typi- cally, in the disconnect enclosure for convenience. Since the shunt produces a voltage drop in millivolts we can run this circuit for a good distance with very smali conductors. The monitor can be in the battery room or a good distance away. Sizing? A 1 to 1 shunt produces 1 millivolt Grop per | amp of current, therefore 100 mv - 100 amp shunt would read 100 amps at 100 miliivoits. A 10 to 1 shunt such as a 50 mv - 500 amp shunt offers less resistance and drops only 50 mv with 500 amps of current. Select a shunt for the maximum sustained current of which you will draw. This is usually determined by the inverter size. Instantaneous and Cumulative Information Common meters report current flow or battery state of charge (voltage) at a single point in time - the present. This type of metering is termed instantaneous. Devices which report instantaneous information are less complex and less expensive and can give a general idea of what's happening. Several of the Controller/Regulator units we sell combine metering functions for reduced costs. When reading battery voltage one must fully understand the pushing and puiling effects of battery voltage to use this type of monitoring. (See Battery section). Cumulative type monitors usually include instanta- neous information, but go a step furtner by recording the power over time. With this information, termed amp hours or watt hours, we can see just how much power we generated yesterday or last month, and how much power was consumed, and with much greater accuracy, determine battery state of charge. Which ever monitor you select, make sure you have a window, so to speak, of the information you require; without it, you are only guessing ana quessing 1s a common killer of batteries. Many of the monitors listed here are compatible with the our Powercenters. Lightning Protection Lightning presents a potential hazard for systems with exposed conductors and aluminum framing mounted on rooftops or adjacent to a building. Direct and close-in strikes can damage sensitive electronic circuitry through the presence of static charges and electromagnetic fields. These forces can induce voltage surges and may damage the system's wiring and components, particularly if your system Is not properly grounded and orotected. While no fightning protection system is foolproof, practical counter-measures are availabie and include a lightning rod at the PV source, adequate system ground- ing, and surge protection on the incoming DC wires and the secondary AC wiring. Water Pumping with Solar Electricity Pumping water with power from the sun is a natural. As the diagram on the right indicates, there are a number of ways to design solar pumping systems. For the remote home owner who utilizes a battery bank, pump types are less varied. The two major water systems for domestic use divide by water source. if your water source is shallow (less than 15’ vertical) from your pump location, a shallow well or surface pump will suffice. These pumps are less expensive, operate at low voltage DC and are of positive displacement design which increases Overail system efficiency. If your water source is a deep well, then a submersible pump is typically the answer. We offer the complete line of solar powered Solarjack DC submersibtes, and AC submersibles wat epstare directly from inverters. : | A typical water delivery system may contain one module to With both of these systems you need to provide pressure hundreds of modules that deliver current to pumping equip- to charge your pressure/storage tank as well as bring the ment. For continuous pumping, battery storage may be added, water into the house. This requires a pressure switch to but for most applications a battery is not required since solar automatically turn your pump on and off as water is needed. systems deliver the most water when the sun is brightest. Another way to create pressure is to pump the water from the water source up to a tank substantially higher than the home. To produce 40 lbs. of pressure, the holding tank would need to be 92 feet above the highest outlet in the house. If this resource is available - great, but installing a gravity system can easily far exceed the cost of a pressure tank and switch. donne CONTROLLER AC Submersible Pumps tn home systems where a battery bank and an inverter are planned or in place, an AC 117 WELL SEAL VAC submersible pump is a good option. Especially where weils are 20 ft. deep or more. These centrifu- gat pumps provide excellent reliability and long life. These units provide a substantial volume of water per minute and DROP PIPE are therefore operated for a short time per day. The size and type of inverter is critical here. The water pump and washing machine are usually operated together and both reauire surge ability from your inverter arid batteries. SAFETY ROPE is. H H HN CHECK VALVE 24 Refrigeration - Your options for energy efficient refrigeration Next to space heating and air conditioning, the largest single energy user in your nome is the kitchen refrigerator. A typical AC powered refrigerator uses more than 3500 watt hours per day. If this refrigerator is run by a solar electric system wnose DC power is inverted to AC by an efficient inverter, then the refrigerator/freezer alone will consume more power than 10 (50 watt) solar electric modules can produce per day. This could be a very expensive way to provide refrigeration. However, there are three good refrigerator options available for the off-grid, solar-powered residence; gas powered refrigerators, DC refrigerators and ultra-efficient, AC refrigerators. Gas powered, absorption, refrigerator/ freezers are the most common solution for off grid refrigeration. tn use in thousands of full time homes and vacation cabins, the propane-fueled refrigerator/freezer units are very reliable and efficient — typically using less than three gallons of fuel per week. Since they don't use electricity, your residential sotar electric system can be smalier and less costly. Today's absorption refrigerator/ freezers are very quiet and safe. The only drawback to these units is that they are smailer than a traditional home refrigerator. The average gas refrigerator is 8 cubic ft. - approximately 1.5 cu. ft. of freezer and 6+ cu. ft. of refrigerator. !f the doors are reversible (such as on a Norcold) then two units can pe placed side by side to provide 16 cu. ft. of refrigerator/freezer space, Another traditional refrigerator solution is the DC refrigerator. These units are tne most efficient, electric- powered refrigerator/freezers available. A 16 cu. ft. unit, in a temperate climate, uses less than 800 watt hrs. per day (the power typically proauced by four, 50 watt solar electric modules). Many energy saving features are built into eacn DC refrigerator such as extra insulation, com- pressors located on the top of unit to avoid heating the cabinet if located below, and separate freezer doors. These reliable units are more expensive than the other options because they are hand built in small factories. The higher initial cost, however, is off-set by the savings in solar system componentry and life-time fuel cost. The final option is a relatively recent alternative; the ultra efficient AC refrigerator. These units, though using more power than OC units, can still be comfortably run by a solar electric system. A typical 16 cubic ft. refrigerator/ freezer uses 1500 watt hrs. per day (using approximately the power of six to eight 50 watt modules, in a temper- ate climate). Usually they are very moderately priced and feature amenities not offered in the other alternatives such as: fresh food section located above freezer section, many compartments and sheives, double door layers in freezer section and fast-freeze options. Ultra efficient AC chest type freezers are also avail- able. These very affordable units oniy use 500 watt hrs. of electricity per day (roughly the power produced by two or three solar electric modules). Though requiring a [little more forethought than just going down to the locai appliance store and picking out a refrigerator/freezer that matches your kitchen, today’s efficient refrigerator options are affordable, reliable, aesthetically pleasing and most importantly, work well with solar electric power. 25 Backup Generators for PV Systems We typically use generators as a supplement to onotovoltaic power. There are some very iarge applications Tor which continuous-use generators may prove more cost- effective than a PV system, but in almost aii of the applications with which we work, the economics of generators are maximized by restricting them to providing Dackup power. Generators are used for backup in situations where seasonal variability of insolation is substantiai as in cloudy climates, or for systems where occasional very large loads are powered, as for intermittent use of large shop tools or a deep well pump in a residence. We typically design residential PV systems to provide 80 to 90 percent of the home's annual electrical power. The jast 10 to 20 percent 's more economically supplied by a generator. The reason for this is simply economics. In many cases cost effective to emoioy a packup source of power during the jeast sunny time of the year. The cost per kilowatt hour of electricity produced by a generator used in conjunction with a battery bank and inverter is much cheaper for residential type load profiles than is power produced by a continuously running genera- tor. This is because enaine-driven generators perform poorly when under-loaged. Low-load hours on the engine, especially diesel, can actually age it more than hours under full load. Fuel costs suffer too. A 6500 watt generator, for example, powering a 100 watt load will consume perhaps 50% as much fuel as it would consume if operating at full capacity. Therefore, work the generator near its capacity for shorter periods and then shut it down. Batteries can be charged while wasning machines, pumps or other large ioads are running. This maximizes efficiency while reduc- we would double the cost of the system to provide this ing generator run time, wear, and fuel costs. last 10 to 20 percent of annual power. It is much more Generators and Battery Charging waits a pre-determined 'warm-up" period then switches over, allowing generator power to flow to the loads. The generator power is now running all loads in the house as weil as powertng the battery charger. Therefore the generator should be sized to not only run the battery charger at a high rate, but aiso any AC loads that may be running at the same time. If the generator is undersized for the loads being run, the battery charging rate will be reduced. This may mean the generator is run for a very long time to fully charge the batteries. Battery chargers take the 120 volt AC power from the generator and convert this power to tow voltage DC. They are typically the largest consumer of the generator's output. Many of today's inverters incorporate a battery charger and transfer switch as optional or even standard equipment. These chargers are powerful, charging the batteries at a high rate and requiring a good sized generator to power them. We recommend a generator of at least 4 to 5 kw in size for full time remote homes. Remember that these inverter/ cnargers also include an automatic transfer switch. This switch selects among the two sources of AC power to be delivered to the loads - inverter or generator power. The So how do you avoid this problem that many have switch is biased to inverter power which is suopiied to the experienced? Simply select a good-sized battery charger and loads whenever the generator is off. Once the generator is generator when designing your system. This is not the place started, the switch senses the presence of generator voltage, to cut the budget, as generator fuel can cost you dearly. Generator Placement and Powersheds Powersheds are a common outbuilding on the remote homestead. They often serve multiple functions of housing the generator, batteries and power conditioning equipment required with your PV system. Beyond this, they ronsladet | can also house tools and equipment as weil as support the solar array if ae TS olaced in a sunny, non-shaded area. It is a good idea to keep fiammable Se fugis and gasses in a separate buiiding rather than the building in which ss one sleeps. Z BN AL Os The sound insulation qualities of a powershed offer another heer oer as < aavantage.. There ts nothing like driving up a beautiful mountain to a ie Fee a picturesque home site, then being greeted py the howling of a S| owen ces y generator as you step out of your truck. Powersheds can be placed a S eae ” [= See, aistance from living spaces, decks and the like. ici_| a if you are thinking of a powershed to house your PV compo- serra S| nents, don't forget that your batteries are most efficient between 60° ior LY tee? Cexeeaton = 2 and 80°F. In cold climates, the tremendous amounts of neat given off IS —— a x oy the generator can aid in heating the space. Propane catalytic heaters — ao” SOS™té‘i*t*CSN ehasts witn thermostats can also help. Excess heat can also be a problem if the SI ; ena oh MENT AN generator is not properly ventilated to the outside. Pil — a Another good idea is to install DC lighting in your shed. With battery airect DC power, you wiil still have jight wnen servicing your AC equipment. LINLRETE Oe wld Fe i 26 ——————— Recreational Vehicle Systems Give yourself the power to go anywhere with the most powerful charging systems under the sun. Solar modules and RV's with batteries are a natural eee match. Since batteries are charged when traveling, RV's nor- mally depend mostly on the vehicle's alternator for the primary power source. Power to charge the battery bank is also provided through a converter when plugged into the utility. However, for those who like to spend days, weeks (or longer) not traveling and not plugged in, photovoltaics can mean freedom. And, because a PV array can put as much power into your batteries during an hour of bright sun as a small gasoline generator, it can also mean reclaiming peace and quiet. As well, the RV's existing battery bank and fuse box make the transition to solar a smooth and economical one. While most of our RV systems utilize 1 to 2 modules, it is Important to analyze your power needs. Just as with ali PV systems, you need to consider the wattage of the appliances and lights you are powering as well as the average hours used each day. Average daily usage can be calculated on the worksheets in the appendix. Unlike most other systems, however, RV's travel through different regions of climate, park at varying angles to the sun, sometirnes in shade and sometimes not. People with similar vehicles can have very dissimilar power usage and patterns of travel, These factors should be considered. if you have any questions about how to go about this, please give us a call. Buy now and save later. Your Solar Charging System will pay for itself several Keeps batteries charged, times over by increasing battery life and reducing the amount of money you spend on campground hook-ups and Summer or Winter. generator maintenance. Batteries that are "deep cycled" too Solar panel output is dependent on light intensity and many times or sit idle for several months can be permanently exposure time in the sun. You'l! be amazed at how much damaged. Solar modules provide a daily maintenance charge power your system provides on a bright day. And even in to your batteries and eliminate this problem. By recharging every day, the depth of discharge is reduced, and battery life and performance are greatly improved. cloudy weather, your panels will produce power although at a jower output. REFRIGERATOR VENT H 120 VOLT AC = = ° ) a { wD; _ / 2 a / as TE |! ee OUTLETS | BLENDER MICROWAVE COFFEE COLOR Tv FANS & WATER LIGHTS : | | MAKER VCR FURNACE PUMP REQuLATOR-| | BLOWER METER PAC a 12 VOLT OC a ANO STEREC 120 VOUT NVERTER CHACUIT ENGINE BREAKEA t 12¥ BATTERIES ALTERNATOR GENERATOR UTHLITY ELECTRIC POWER ; / 120 VOLT AC (WHEN AVAILABLE)“ a — Photo courtesy of Kyocera America, inc. ee 28 Perfect for the energy conscious homeowner or vacation cabin. This system will provide a combination of 12 volt DC and 120 voit AC CABIN Example System power without the noise and hassle of a generator. Enjoy the benefits of silent electricity such as music, lighting, pressurized delivered water 100 to 500 Watt Array ~ all at your perfect "get-away" spot. 12 Volts Nominal* Example system power production 830 watt hours daily from a S hour equivalent day. AC and DC Loads Batteries - 12 voit - 86 amp hour each, seaied type Inverter - 1500 watt modified sine with built-in Fixed Module Mount battery charger Stacking Vertical Configuration Roof Mounted TILT ROOF MOUNT ARRAY Roof or Ground module mount In this drawing we mounted the modules on the rocf. The modules can be mounted anywhere there is good sun and as close to the batteries as possinie. We offer a number of different mounting structures. Battery Enciosure We suggest placing the batteries in an enclosure for protection and ease of ventilation to the exterior. How much room does this system require and where should it be piaced? A wall area 3' x 5' and a floor area 1.5' x 4' will handle this size system nicely. This system can be placed in a basement or utility area of the dwelling or in a power shed. BATTERIES IN VENTED ENCLOSURE *This system could easily be configures 0 24 voits. However, 12 voit appliances are much easier to locate than 24 volt units. An inverter and common 117 VAC appliances alleviates this problem. CABIN Example System Component Description Solar Modules 2-6 modules typical 40-80 watts each Module Mount Structure Fixed or tracking, roof, ground or pole mount for selected number and size modules. Module interconnects weatherproof material incasing wiring between modules. Combiner enclosures and breaker for paraliel connections at array. Cable run from combiner box to Controller Breaker Box total out and back distance. Controller Breaker Box - protects controller and cabling. Controller Prevent battery overcharge. Amperage rating determined by array size, monitoring can be included in unit. Main 8a u ect Protection of ali circuits from battery overcurrent. Current limiting fuses and disconnect. Also serves as central wiring enclosure. Misc. contro! area cabling. Battery Cabling from batteries to disconnect, and inverter. Battery Bank” 2 to 6 - six or twelve volt battery dullding blocks Battery interconnects - cables between batteries Battery bank enclosure protects batteries and people, provides for battery ventilation to out-of-doors. DC Breaker Box Disconnect protection for each DC circuit. Breaker required for each circuit. In for AC power 250-2500 watt inverter with built in battery charger and transfer switch, if required. AC Distribution/Breaker Box for inverter output The system outlined here should serve as a guideline. The price will vary depending upon your requirements and the specitic components you select. A generator can be included with this system if required. Your System Item Price Specifications 4-51 watt modules. Roof top mount - fixed, vertically stacked. 4 moduies Appropriate number and length. Breaker Box w/ breaker. Appropriate fength and size cable. Breaker Box with 2 pole breaker. 12 to 40 amp, 12 voit controller w/built in monitor. Main DC Fused Disconnect - 200 amp, 2 pole. Two class T fuses. Appropriate length and size cable. One set of 2/0 inverter/battery cable of appropriate iength. 4-12 volt solar batteries. Heavy gauge, appropriate number & lengths. 4-battery fiberglass box with ventilation pipe fitting. DC rated, size determined by numbers of breakers required. Appropriately sized inverter with conduit enclosure. AC rated, size determined by number of breakers/circuits required. Total Value *3,200° to °4,800°° "Battery maintenance kit suggested, inciudes detailed battery book, anti-corrosion spray and hydrometer. ees Not included - ground rod & clamp, miscellaneous wire and hardware. Digital multimeter is suggested for installing and maintaining tnis system. 30 GENVERTER Example System PROBLEM: Gener ator/ Inverter/ Battery On a budget that prevents you from buying the complete system you need and you already have a generator? By coupling an existing generator to a battery charger, battery bank and inverter, efficiencies are increased and costs are decreased. Previousiy, the most common power source for homes off the utility line was a gas or diesel generator. As long as this generator is run close to its rated capacity, efficiencies are maximized and costs are kept relatively low. However, this is usuaily not the practice. Many generators without battery banks are run 16 hours a day or more at only a smail fraction of their potential power. This results in the cost per kilowatt hour of electricity going sky high. Now consider the addition of a battery bank, a battery charger which operates wnenever the generator is run, and an inverter which powers the AC loads from the battery bank whenever the generator is off. This can reduce daily generator run time and dramatically reduce the cost of power. In some instances, efficiency can be increased even further by sizing the generator to run occasional very large loads and thus avoiding the need for an extra-iarge inverter and additional battery capacity. in this type of system (which we term a “genverter’), a transfer switch, either manual or automatic, is utilized. This switch receives power from either the generator or the inverter and passes only one source to the loads. Many inverters have three of the major components necessary for this system. The inverter, battery charger and transfer switch are designed into one unit. An option for this type of system which increases efficiencies even further is the addition of select DC loads such as refrigeration which can be powered directly from the batteries. You will notice this system drawing to be very similar to the other system schematics. In fact the oniy major difference is the lack of solar modules, mount structure and controller. SOLUTION: Start with a working portion of your system as detailed here, adding solar or wind generators as your budget allows. Solar modules and wind modules can easily be added incrementally. 3/4" Plywood Backplate Breaker Box MIM -CTMQ wy id pny ar ma aN Ga eo ue ce te nn igniter =S—4 Optional Seneraior -- zs Inverter/Charger Breaker fe See eo eee Box ee ete eee ee ee ee 31 GENVERTER Example System The system outlined here should serve as a guideline. The price will vary depending upon Generator /Inverter /B attery your loads and the exact components you select. Component Description B From 220 to 1500 amp hr. Typically 24 volt. Battery Interconnects cables between batteries. Battery/Inverter cables cables between battery and disconnect and disconnect to inverter. Battery enclosure Protection of all circuits from battery overcurrent. Current limiting fuses and disconnect. Also serves as central wiring enclosure. } Converts DC battery power to AC power. Typically 1,500 to 5,500 watts modified or full sine wave. AC Distribution Panel Provides breaker space and distribution of AC power to circuits G aker Panel Protects cables from generator, handles generator only loads. Monitor Reads voltage and amperage flows from the battery charger and to the inverter. Total Value 57,500” to *11,000°° with 6.5 KW generator. Specifications Your System Item Price 4-116 Batteries* 370 amp hrs. at 24 voits. 3-12" - 2 gauge interconnects. One set of 10' - 4/0 or 2/0 cables cut to required lengths Fiberglass, acid resistant plastic or metat enciosure to battery footprint. One or two pole - 200 to 400 amp fused disconnect w/fuse(s). inverter/charger w/built in Transfer switch. 24 volt input. Six to sixteen position AC distribution box w/breakers Two to six position AC distribution panel w/breakers Instantaneous or cumulative meter w/shunt Total Value 52,600 to 56,000° without generator. “Battery maintenance kit suggested. Not included - ground rod & clamp, miscellaneous wire, 4 hardware and conduit. WIND POWERED Example System Wind Generators add versatility to your charging regime Wind generators are an excellent compliment to many battery based systems. One or more wind chargers can easily be added to the genverter system described here, or to any of our example systerns. Many wind genera- tors Include built in battery overcharge protection so the only other components necessary are the tower, power cabling and a designated DC circuit breaker at the central wiring enciosure. The addition of a wind generator diversifies the charging sources which in turn, increases the overall system reliability and can extend battery life by maintaining higher average states of charge. Total Vaiue *600 to 52,400 per wind generator. 32 RESIDENTIAL Example System FIXED MOUNT ARRAY 400 to 1000 Watt Array 24 Volts Nominal Primarily AC Loads, Select DC Loads Typicai full time home system or farge vacation part-time home. This is a very common remote home system size. The solar array, batteries, or inverter size can be customized to your specific needs easily, giving you the most power for your dollar. Example system power production 1800 watt hours daily from a 5 hour equivalent day. Batteries - L-16 type, 6 volt, 300-370 amp hours. inverter - 1,500 to 3,600 watt modified sine with built-in battery charger and transfer switch. Power conditioning and storage placement - dwelling base- ment or utility area, powershed or container. COMBINER, BREAKER. AND UGHTNING PROTECTION ENCLOSURE INVERTER WITH QUILT IN BATTERY CHARGER ee mice) This is one of our most popular systems, The monitor can be installed in the power room or remote, possibly in the living area of the house. Wail space required for the system is typically 4' x 5" and floor space for the battery bank is 2' x 4.5". A popular addition to this system is a single DC light fixture to light the contro! area, providing tight in the control room even when the inverter is shut down. This drawing illustrates how a PV system breaks down into three major sub- systems. Array at the top, Power Condi- tioning at page center, and Battery Bank below. We can easily take any of these sub- systems and alter the others. For example, the array or battery systems could vary greatly tn size. 33 een er ee ee AA sea ras SssvvSRSIssssssssnoinmmannn RESIDENTIAL Example System Component Description A UB-SYSTEM Solar Modules 6-12 Modules 51 to 120 watts each typical Module Mount Structure Fixed or Tracking roof or ground or pole mount for selected numper and size modules Module interconnects weatherproot conduit incasing wires between modules Combiner Enclosure with breaker for parallel connections at array with opttonal lightning protection Cable run from combiner box to controller breakers total footage out and back POWER CONDITIONING SUB-SYSTEM Powercenter Enclosure and Backplate includes: Controller Prevents battery overcharge Amperage rating determined by array size Main Battery Fused Disconnect Protection of ail circuits from battery overcurrent Current limiting fuses and disconnect Ground terminal strip included. Monitor Reads battery state of charge, current in and out of battery. Unit may also read cumulative amp hours remaining in battery. Battery cabling - from batteries to disconnect Disconnect to inverter DC Load Breakers Overcurrent protection for each DC circuit. Inverter For AC power Includes built in battery charger and transfer switch. 1,500 to 3,600 watts continuous typical Inverter Output breaker box and breakers Protects and distributes AC power from inverter. Generator input breaker box and breaker required if main generator breaker is not within reach. BATTERY BANK SUB-SYSTEM Battery Bank 8 to 12 - six volt batteries from 220 to 370 amp hours typical Battery interconnects - cables between batteries Battery pank enciosure orotects batteries and people, provides for Dattery ventilation to aut of doors. The system outlined here should serve as a guideline. The price will vary depending upon your requirements and the specific compo- nents you select. Specifications Your System item Price 8-60 watt modules 2-4 module, fixed, vertical mounts Appropriate number and Jength. Breaker enclosure with two breakers and lightning protection. Appropriate length and size cable. 60 amp, 24 volt controiler with circuit breaker. Two pole 200 to 400 amp fused disconnect with 2 fuses. Shunt included with monitor. 2/0 to 4/0 cable set of appropriate length. DC rated, one breaker of appropriate amperage for each circuit. inverter/Charger 24 voit, input AC rated, size determined by number of breaker/circuits required. Two piace breaker box with breaker 8 - 6 volt, L16 type batteries Heavy guage, appropriate number and lengths. Sized to number, dimensions, and arrangement of batteries. Total Value *7,600 to °9,800° Battery maintenance kit suggested, includes detailed battery book, anti-corrosion spray and hydrometer. A digitai multimeter is suggested for maintaining and installing this system. Not included - ground rod & clamp, miscellaneous wiring, and miscellaneous nardware. 34 ee —— eee POWERLINE Example System For the serious homeowner with needs for a healthy amount of househoid power. This homestead system incorporates a good sized array with sinewave power conditioning and heavy duty long-lived two volt batteries. The b ITF fi ad i 800 to 4,000 Watt Array stijortha Aeslbaiy of saan ee ee 24 or 48 Volts Nominal All AC Loads Example system power production 3,700 watt hours daily from a 5 hour equiva- lent day. Solar Array - Fix mounted on ground, roof or pole mounts. Tracking pole mounts also available Batteries - 2 voit cells in 3 cell trays, flooded or sealed type. Inverter - sinewave inverter/charger. Power conditioning and storage placement - Basement, powershed or container. Remote monitoring and generator start/stop. Wind generator for diversity of charging sources. Propane generator for battery charging during prolonged no-sun periods. REMOTE MONITOR INVERTER W/BUILT—IN BATTERY CHARGER RT | REMOTE f=. VENT Cars =F am, (aE . aa ae fim KEYS VANE AIAG FY A SO — Ys — OY en a Ya — f ‘TI t BATTERIES IN VENTED ENCLOSURE - A second inverter can easily be added to this system for additional capacity and 230 VAC loads. - The Powercenter can also include inverter AC output breakers. 35 oe — ee POWERLINE Example System Component Description Solar Modules 12 to 48 modules typical 51 to 120 watts each Fixed or tracking, roof or ground mount for selected number and size module Module interconnects Weatherproof conduit encasing wiring between modules Combiner enciosures for parallet connections at array Lightning protection - SOV in combiner box. Cable run from combiner box to powercenter total footage - out and back wer E ur One enclosure which encompasses a number of components inciuding: Array input breakers, controlier(s), manitoring of battery state of charge, input and load amperage. DC load breakers, main battery disconnect and current limiting fuse, automatic generator start/stop by battery state of charge, grounding terminals. Battery/inverter Cables Cables from battery to powercenter and from powercenter to inverter. AC power from the battery bank 2,000 watts to 5,500 watts typical. AC input breaker protects inverter output circuits. Generator breaker box protects generator powered circuits, Battery Bank 24 or 48 voits typical 700 to 3,000 amp hours capacity typical 2 volt cells as building btocks Battery enclosure Generator 6.5 to 10 KW typical Propane fuel, remote start/stop. 500 to 1,000 watt unit typical with controller Cable run from wind piant to powercenter total footage - out and back The system outlined here should serve as a guideline. The price wiil vary depending upon your requirements and the specific components you select. The larger the system, the more options that are available. Your System Item Price Specification 12 -80 watt modules Pole mounted, fixed structure 6 moduies per structure. Appropriate number and length. Parallel combiner boxes w/built-in lightning protection. Appropriate iength and size cable. Powercenter and backplate of appropriate amperage, voltage and number of inverters. 1-60 amp controller. On board and remote monitoring. 1-DC input breaker for wind generator of appropriate amperage. One 4/0 cable set of appropriate length from batteries to powercenter, One 4/0 cable set from powercenter to inverter; Sinewave 24 voit inverter/charger 4,000 watt continuous output. One two place breaker box and one breaker One six place breaker box and 4 breakers 24 volt system - 12 cells of 1015 amp hour each (three cells per tray) Fiberglass, acid resistant plastic or metat to battery footprint. Slow speed, sound attenuated, stationery unit. Total Value £16,000” to $28,000 without generator. 600 watt wind generator - 2 blade with controller Appropriate size and length. Add £600 to 2,400 per wind generator. Battery maintenance kit suggested, includes detailed battery book, anti-corrosion spray and hydrometer, Not included - ground roa, miscellaneous wire and hardware, and ventitation system for generator. wind generator mast, poles for mount structures, propane plumbing 36 Appendix Wire loss table - 5% This is a five percent table which means at these amperage ratings at the listed distances, 5% of the power would be lost to friction. Five percent ts normally acceptable in low voltage systems, but if you want a 2% figure, divide the given distances by 2.5. For a 10% loss multiply the distance by 2. For distances at 48 volts, double the 24 voit distances for a 5 percent loss figure. For 240 voit 5% loss, double the 120 voit distances. These distances include the NEC requirement for current oversizing of 25%. Example: For a pump drawing 9 amperes at 24 volts, located 88 feet from the battery bank: look at the center table for 24 volts. In the far left column find the next number higher than 9 (which is 10) and follow that line across the table until you find a distance figure greater than 88. At the top of the column find the gauge of wire (#8) that should be used. This method insures that wire losses are kept to an acceptable levei without spending too much money on extra-heavy cable. Using a heavier wire than indicated, however, will result in even higher efficiencies and we do sometimes invest in the next larger gauge. In the lower jeft corner of each table you will see some blank entries. These denote amperage flows that exceed the “ampacity” of the wire, where power loss is so severe that the heat buildup threatens to melt the wire. Do not use these configurations! Amps Wattage #14 in Wire at 720V 1 120 2 240 422.25 4 480 187.5 6 720 141 8 960 103.5 10 1200 84.75 15 1800 56.25 20 2400 25 3000 30 3600 40 4800 50 6000 Amps Wattage #14 in Wire at 24V ] 24 169.5 2 48 84.75 4 96 37.5 6 144 28.5 8 192 21 10 240 17.25 15 360 11.25 20 480 25 600 30 720 40 960 50 1200 Amps Wattage #14 in Wire at 12V } 12 84.75 2 24 42.23 4 48 18.75 6 72 14.1 8 96 10.35 10 120 8.48 15 180 5.78 20 240 25 300 30 360 40 480 These are one-way distances, measured from point A to point B. The out and back nature of electrical circuits has already been included, #12 656.25 328.5 225 159.75 131.25 84.75 65.63 #12 262.5 134.25 66 45 32.25 26.25 17.25 13.5 #12 131.25 65.63 32.85 22.5 15.98 13.13 8.48 6.6 #10 516 328.5 272.25 216 131,25 103.5 84.75 65.63 #10 412.5 207 103.5 66 54 43.5 26.25 21 17.25 13.5 #10 206.25 103.5 51.6 32.85 27.23 21.6 13.13 10.35 8.48 6.6 562.5 422.25 337.5 225 4~8.75 131.25 112.5 84,75 67.5 675 337.5 169.5 112.5 84.75 67.5 45 37.5 26.25 22.5 17.25 13.5 #8 337.5 168.75 84.75 36.25 42.23 33.75 22.5 16.88 13.13 11.25 8.48 666 534,75 356.25 272.25 216 178.5 131.25 103.5 532.5 267 178.5 133.5 107.25 71.25 $4.75 43.5 36 26.25 21 #6 532.5 266.25 133.5 89.25 66.6 53.48 35.63 27.23 21.6 17.85 13.13 562.5 422.25 337.5 281.25 216 171 282 216 169.5 112.5 84.75 67.5 56.25 43.5 34.5 432 216 141 108 84.75 56.25 42.23 33.75 28.13 21.6 675 543.75 450 337.5 272.25 270 180 135 108.75 90 67.5 54.75 675 337.5 225 168.75 135 90 67.5 54.38 45 33.75 1/0 722.25 543.75 431.25 1/0 289.50 217.50 172.50 144.75 108.75 86.25 1/0 543.75 360.75 272.25 217,50 144.75 108.75 86.25 72.23 54.38 2/0 675.00 543.75 2/0 270.00 217.50 480.00 135.00 108.75 2/0 675.00 450.00 337,50 270.00 180.00 135.00 108.75 90.00 67.50 3/0 684.75 3/0 343.50 274.50 228.00 171.00 137.25 3/0 570.00 427.50 342.75 228.00 171.75 137,25 114.00 85.50 vwetrt—O mS AN uct—Oo <= ON-= wer—O cg N= Appendix 37 Battery Installation and Wiring Batteries may be wired in either series or parallel configuration. When a battery is wired in series the positive terminal is wired to the next battery’s negative terminal. This increases the voltage while maintaining amperage of the two batteries. With parallel wiring the positive terminal is wired to the next battery’s positive terminal, and the negative to the next negative. This arrangement increases amperage while maintaining voltage. One common mistake is to believe that both amperage and voltage will increase when wiring batteries together. It will not; only one value will increase with respect to the arrangement. A battery bank may combine both series and parallel wiring configurations. Series strings of batteries are used to achieve the correct voltage, then a number of these series strings are attached in paraile! to increase the amp hours of the total battery bank. 12 VOLT BATTERIES @ capacity © 90AH eo eso ®@ CAPACITY 180AH 24 VOLT SYSTEMS 12 VOLT SYSTEMS CAPACITY @® capacity © CAPACITY 1S) 360AH 6 VOLT BATTERIES CAPACITY 12 VOLT SYSTEMS 24 VOLT SYSTEMS 8 @ capacity O 220AH CAPASITY ® 740AH © CAPACITY 1480AH 12 VOLT SYSTEMS CAPACITY CAPACITY 1476AH 38 Appendix Sr yeu ei SSCS Solar Array Sizing Worksheet Use these worksheets to determine your solar and battery requirements. We have included an example column and a column for your system, Give us a call if we can be of help. WINTER YEARLY AVERAGE WINTER YEARLY AVERAGE Example: 1. Locate your site on the Winter and Average yearly insolation map on page 6 and list tne nearest figures. 2.5 5.0 2. Take the daily corrected total loads in watt hours from your load catcula- tlons sheet. 1000 1000 lu . Divide line 2 by line 1. This is the number of watts we need to generate per hour of full sun. 400 200 4. Find actual power produced by your selected module and enter here (rated amperage x battery voltage during charging). Exampte: Using MSX-60's, one module produces 3.5 amps. 13 volts is a common charging voltage for 12 volt systems. Actual power = amperage x charging voltage. (3.5 x 13) 46 46 5. Divide line 3 by line 4. The result is the number of modules required for your system. When rounding this number, remember that sets of 2 modules are neeced for a 24 volt system, sets of 4 for 48, etc,. You can see from the example that almost twice the number of modules are required in the winter because in this instance we have half as mucn available sunlight. In northerly climates this is often aggravated by a larger wintertime demand for more lights, etc. For this reason we often size residential solar power systems (in the interest of cost-effectiveness) to provide 100% of summer or yearly average loads and meet the winter shortfall with a generator. Remote communications are generaily sized to winter conditions. Example: a e e@ Battery Sizing Worksheet 1, Determine total watt hours per day required from your joad calculation, 1000 2. Determine days of storage required. This approximates the greatest number of cloudy days in a row expected (3 to 7 is common for residences, 7 to 14 for 7 remote communications and monitoring sites). 3. Multiply jine 1 by line 2. 7000 4. Determine planned depth of discharge, 80% is the maximum for Jead acid deep cycle batteries, 50% a common amount for optimum longevity. Divide (.50) line 3 by .80 or .50, respectively. 14,060 5. Derate your battery for low temperatures by muitiplying line 4 by the factors in the table below using jowest expected weekly average temperature. 15,540 Battery Temp. F° Multiplier Battery Temp. F° Multiplier a0 1.00 40 1.30 70 1,04 30 1.40 60 1.11 (exampie) 20 1.59 50 1.39 6. Find the watt hour capacity of your selected battery. This is voltage times 2100 ampere nour capacity. Example; L-16 deep cycle, 6 volts x 350 amp hours. 7. Divide line 5 by line 6. The result is the number of batteries required. 7.4 8. Round number of batteries to fit system voltage. Example; A 24 volt system requires sets of 2 when using 12 volt batteries, sets of 4 when using 6 volt 8 batteries and sets of 12 when using 2 voit cells. Note: The battery bank amperage should normaily be at least 5 times the hourly amperage draw of the largest appliance or 5 times the highest hourly amperage output of the battery charger. Appendix 39 = Please. copy iftmore-: san one: o shone squint Appiiance Wattage (Volts x Amps) Hrs. Per Days Per rs Avg. Watt- Mult. by 1.15 for AC Day Week Hrs./Day aa ae a Se ee 2 ee Pe fe es Fi a a 2 2) ee X i ih rt a RC Se 2 x od PS TSS Ps Done | é~< ha iT il BEING \ lead WL nt > \ ~ «| xX HET hl | \ | ee 4 HIGHEST AC LOAD IN TOTAL AC CONNECTED UL ia Mga HOURS WATTS: WATTAGE AT ONE TIME: PER D Ug a eat +] Ener eho =| CORRECTED WATT-HR PER DAY: | a *The load correction factor ts required as batteries are not 100% efficient and other losses occur in a system. We increase the load value by 30% to compensate for these losses. Appendix 41 Inverter Overcurrent Protection, Cable and Powercenter Sizing Chart Overcurrent Minimum Powercenter Brand Continuous Maximum Protection Cable Minimum Name Model Wattage Voltage Input Amperage In Amps Size*** Size**** Stat Power 150-12 150 12 16 20 #4 - Stat Power 250-12 250 12 27 40 #2 - Stat Power 250-24 250 24 13 20 #4 - Stat Power 800-12 800 12 86 110 #2 3-202 Stat Power 800-24 800 24 43 60 #2 - Stat Power 1500-12 1500 12 160 200 2/0 3-202 Stat Power 1500-24 1500 24 80 100 #2 3-202 Stat Power 2500-12 2300 12 246 300 4/0* 3-404 Stat Power Prosine 1.2-12 1200 12 128 175 2/0 3-202 Stat Power Prosine 2.5-12 2500 12 267 400 4/0* 3-404 Stat Power Prosine 2.5-24 2500 24 134 175 2/0 3-202 Exceltech 250-12 250 12 27 40 #2 - Exceltech 250-24 250 24 13 20 #4 - Exceltech 500-12 500 12 54 100 #2 3-202 Exceltech 500-24 500 24 27 40 #2 - Exceitech 1000-12 1000 12 107 150 2/0 3-202 Exceitech 1000-24 1000 24 53 100 #2 3-202 Exceltech 2000-12 2000 12 214 250 4/0* 3-404 Exceltech 2000-24 2000 24 107 150 2/0 3-202 Trace 812 575 12 62 100 #2 3-202 Trace DR1512 1500 12 160 200 2/0 3-202 Trace DR1524 1500 24 80 100 2/0 3-202 Trace DR2424 2400 24 128 175 2/0 3-202 Trace DR3624 3600 24 193 250 4/0 3-404 Trace 2512 2500 12 267 400 4/0* 3-404 Trace 2548 2500 48 67 100 2/0 3-202 Trace SW2512 2500 12 267 400 4/0* 3-404 Trace SW4024 4000 24 214 250** 4/0 3-404 Trace SW4048 4000 48 107 150 2/0 3-202 Trace SW5548 5500 48 147 200 2/0 3-202 Maximum input Current defined as continuous power divided by 11,22, or 44 voits respectively at an inverter efficiency of 85%. *This size cable is for free air installation only. If these cables are installed in conduit, NEC sizing requires doubling these conduc- tors - two positive and two negative cables. Please call when sizing these inverters. **The 4024 sinewave is within the ampacity of 4/0 cable if installed with 250 amp overcurrent protection. If installed with 300 amp overcurrent protection - doubie 4/0 cables are required. ***75° cable - Derate by .8 for parallel conductors - Please refer to NEC table 310-16. Cable sizes are good for up to 10' of length, one way distance. Rounded to available product sizes. =***Powercenter DC load amperage is not inctuded in this sizing - make provisions if present. GLOSSARY ._ Jefinitions ana explanations of terms ana words usea wnen working with solar electric systems. AC - Alternating current. Electrical enerey which reverses its direction at requiar intervais. AC Daily Power Budget - The daily arount of watts your AC appliances use. AC Inverter and Battery Power Allowance - Running an inverter draws a small amount of power from your battery. So does keeping power stored. The inverter and battery aitowance in your power calculations help make certain enough cower will be proauced to keep your battery fram running in the rea. Adjusted Total Daily Power Budget - 4 ‘ota! daily power budget may be changed to meet certain situations. For instance, if you spend only weekends at a nouse, then your adjusted total daily power budget will be jower. Adding a generator to your system also reduces your total daily power budget. The adjusted daily power budget provides the figure that determines the size of your solar electric power system. Ampere or amp - Electric current is measured in amperes or amps. Amp Hours - The numoer of amps useg or produced in a given hour equais the number of hours. Batteries are rated in amp nours. Array - A group of solar electric modules connected together in a power system. Battery Bank - A group of batteries wired together to store power in a solar electric system. Allows you to use the stored power at t@ht, on cloudy days, or to run more power than the array can __foduce at one time. Centrifugal (Water Pumps) - Rotating cutward, away from the center, as in centrifugal force. Controller - Simply put. the controller requiates the current from solar charger to your battery bank Current - The rate of flow of an electric charge. Current is measured in amos. OC - Direct current. Electrical energy flowing in one direction and of substantially constant value. DC Daily Power Budget - The number of watts your DC appliances use daily. Fall (Water Pump/Hydro Sections) - The vertical descent of water, usually measured in vertical feet. Also cailed “head”. Fiow Rate - Speed at wnich water moves. GPM - Gallons per minute. Ground Mount - A piece of equipment upon which soar modules are mounted. Head - See “Fall” Hertz or Hz - the frequency of electrica: current described in cycles per second. Appliances in the U.S. use 60 Hz. Appitances in other countries generally use 50 Hz. ‘ydroelectricity - Electricity created by water power ” Hydrometer - An instrument used to measure state-of-charge (voltage) of a battery. Inverter - An appliance used to convert independent DC power into Standard household AC current. Kilowatt or kW - a thousand watts. (See Watts.) LED- Lignt emitting diode. These lights are often used to indicate low power on modern electronic equipment. Line Loss - Voltage drop over the length of electric line wire. Line lass robs your system of power when wire is too smail for the load being run through the line — or when voltage 15 too low for the distance the power must travel. Load - The lights or appliances run by your electrical system. mA - Milliamps. 1000 mA = 1 amp. Module - Modular solar electric charger; used interchangeably with solar electric panel. Parailel Wiring - A system of wiring, for solar electric modules or. batteries, which increases amperage. Paraliel wiring is “+ ta +” (positive to positive) and “~ to —" (negative to negative). Photovoltaic - Converting light into electricity. Photo means “light,” voitaic means “electric”. Often referred to as “PV” for short. More commonly referred to as “solar electric.” PSI - Pounds per square inch Self-Regulating - Some modules have a speciai circuitry which keeps the battery from overcharging. This means that no controiler is needed when the self-requiating module is properly matched to battery storage capacity. Series Wiring - A system of wiring, for solar electric modules or batteries, which increases voltage. Series wiring is “+ to -" (positive to negative). Singie-Crystal Silicon - Many solar chargers use single-crystal solar cells as they are the most efficient ceil on the market. Pure silicon is grown into crystalline ingots which are cut into thin slices to make solar electric cells. These ceils are then soldered together to meet the charger's voltage and Current requirements. Solar Ceil - The smallest basic solar electric device which generates electricity when exposed to light. Solar Electric - The preferred term used to describe something which uses sunlight to produce electricity. Photovoltaic is the more technical term. Thin-Film Silicon - The tiny solar chargers found in calculators and wrist watches are solar thin-film. Thin-fiim solar chargers are made by spreading a micro-thin layer of silicon on glass and creating the voltage and current circuits using taser technology. Thin-film chargers are produced in sizes from the microscopic calculator chip, up to the 1 x 4 power module. Total Daily Power Budget - in a DC system. the daily amount of watts your DC appliances use, plus the battery power allowance. In a DC and AC system, the daily amount of watts OC and AC appliances use, plus battery and inverter power allowances. Voltage or Volts - Voltage 1s the rating of the amount of electrical pressure that causes electricity to flow in the power line. If electricity were water, voltage would measure the amount of pressure at the faucet. Watts - A watt is a measurement of totai electrical power. Volts x amps = watts. Watt Hour - The quantity of electrical energy used or produced when one watt is used for one hour Safety Precautions Photovoltaic Modules will be “live” upon exposure to light. There will be a voltage present on the output terminals. This voltage will vary according to the type of the photovoltaic module. The array will generate voltages substantially higher than the system nominal voltage, thereby resulting in a shock hazard. This hazard may be minimized by completely shading the array before making these connections. Extreme care should be exercised when working with batteries. Batteries contain a high discharge current capacity and caustic compounds are present. Sparks, flames, smoking materials, etc. can ignite the gases of some batteries. Eyes, face, and hands should be protected. Tools should be used with care. Carefully read the installation instructions before attempting to electrically connect any part of the power system. Most charge controllers are permanently damaged if the battery polarity is reversed when it is connected the controller. 1.0 Solar Array Wiring Solar modules Direct mount and Multi mount frames have cords attached to them. These cords contain a red and black wire. Red is the positive and black is the negative. Solar Modules with Universal frames have junction boxes. Inside the junction box is a terminal strip. eb VIGININIG|S CI 12 3 4 5 6 The terminals of the terminal strip are identified as the following. #1 & #6 are unused terminals. They are typically used in large arrays to feed wire through the junction box. Terminal #2 is 12 volts positive. Terminal #5 is 12 volts negative. 11 12 Volt BP Solar (Solarex) Wiring 12 volt solar arrays are wired in parallel increasing their current output. For example, if two 12V 3.5A modules are wired in parallel the total solar array output will be 7A @ 12V. TOSS TOSS ! ! +12V | | ==> st ~=tey SSSI SISISISIS THIS SISISISSIS ! day | | | | Sein © 8 fee SO Ss See Se re ieee ee 2 “=12y. 1.2 24 Volt BP Solar (Solarex) Wiring 24 volt solar arrays are wired in series increasing their voltage output. For example, if two 12V 3.5A modules are wired in series the total solar array output will be 3.5A @ 24V. These series sets of modules can then be wired in parallel to increase the current output of the solar array. For example, if four 12V 3.5A modules are wired in a series\parallel combination the total solar array output will be 7A @ 24V. SSHHLS ISHISS ! +24V | .24V SINISIS aS os sisi SINISIS a os Ss | | +24V aS ah OO ey ieee anaes ed .24V 1.3 48 Volt BP Solar (Solarex) Wiring 48 volt solar arrays are wired in series increasing their voltage output. For example, if four 12V 3.5A modules are wired in series the total solar array output will be 3.5A @ 48V. These series sets of modules can then be wired in parallel to increase the current output of the solar array. For example, if eight 12V 3.5A modules are wired in a series\parallel combination the total solar array output will be 7A @ 48V. Please note the addition of bypass diodes in the 48V solar array. Do not install a 48V solar array without these diodes. Please read section 1.4 for greater detail. SISSIES VS QS WS QS WS aS iss aay TP] aay / -48V 1.4 Bypass Diodes In solar arrays over 24V bypass diodes must be installed to protect the solar cells. Bypass diodes, also known as shunt diodes, are used in photovoltaic arrays to allow for current to flow around cells or modules that for one reason or another (usually shadowing) are producing less current than the others in a series connected string. There are two reasons that this "bypassing" of shadowed (or damaged) cells and modules is desirable. First, it may be possible to still obtain some useful output from the string of cells or modules even if one or more cells or modules is shaded. Second, in some systems enough voltage is present to force current to flow even through a damaged or shadowed cell. This can force the shadowed or damaged cell to dissipate a large amount of power resulting in localized heating with potentially catastrophic effects such as melting interconnects and charring and burning of the encapsulant. This is clearly a safety issue and is the main reason that bypass diodes are required on higher (>24 V) voltage systems. All large modules have been designed for multiple series connections to accommodate a bypass diode every 18 cells. This is the principal reason for the dual voltage four terminal output found on all BP Solar (Solarex) large power modules. The voltage built up across 18 cells is insufficient to damage a cell even under extreme conditions of temperature and shadowing. Using larger numbers of cells between diodes allows for substantially more voltage to build up creating more heat and possibly resulting in module failure under worst case conditions. The bypass diodes are installed at the manufactured in every large module. Although diodes are relatively reliable they can still fail. When they do fail it’s usually in a shorted or conducting condition. This kind of failure in a bypass diode would result in the entire string of "protected" cells being shorted out and contributing no power to the array. 1.5 Blocking Diodes Blocking diodes are different then bypass diodes. The diode in most cases is physically the same. However it is installed differently and serves a different purpose. A blocking diode only allows current to flow in one direction. If you have a charge controller in your system you do not need a blocking diode to prevent the solar module from discharging the battery at night. All charge controllers have night time discharge protection built into them. Adding a diode with a charge controller to prevent battery discharge at night is redundant and will consume power from your array during the day. The only time a blocking diode is used is when you have an array of 2 or more modules and the array is partially shaded. When a solar module is partially shaded its power output is drastically effected. If this module is connected to another solar module. The output of both modules will be effected even if only one of the two modules is shaded. If you have an array with a shadow that passes over the modules one module at a time it is recommended that a blocking diode be added to each module. An example of this might be a pole that is in front of the array. The shadow is small and will move over the array as the sun moves through the sky. If the array is totally shaded at approximately the same the day then adding a diode will most likely consume more power then it will save you. For example, if your array a large full tree that casts a shadow on the total array. I would look at relocating the array or trimming the tree before adding a blocking diode to the system. Example Wiring with Blocking Diodes 1.6 + + = + a + = SSISSss SISISISSS SISISSISIS SSISSes | | | ! +12V Seer a eae aie eee Harel peste bee aide aed Cosette, eae Eee -1eV a pO ee + -/ \4 = + -/ \+ = SISISSes SINISISIS IISISIEIS JSpHss ! +24V Se eee ee ee eee eee eee fn Re oes ee ae -24V TN - 8 -)0UOC + —/ \+ —/ \+ -/ \+ - VIO G'S Qe SSIS) QS CS) QS Q|S ey ey a [oes xe ale see -48V http://www.solar-panels-for-energy.com/ http://www.ajlsolarelectric.com/ http://www.atlanticsolar.com/