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.

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OLAR PANEL INFO

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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(/)

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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.

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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(=)

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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

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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.

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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

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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.

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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.