7524357 Consumer Photo Voltaic Systems a Buyers Guide

8/13/2019 7524357 Consumer Photo Voltaic Systems a Buyers Guide

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Natural Resources

Canada

Ressources naturelles

Canada

PhotovoltaicPhotovoltaicSystemsA Buyers Guide


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Photovoltaic Systems: A Buyers Guide

This guide is distributed for information purposes only and does not necessarily reflect theviews of the Government of Canada or constitute an endorsement of any commercial productor person. Neither Canada nor its ministers, officers, employees or agents make any warrantywith respect to this guide or assumes any liability arising from this guide.

Her Majesty the Queen in Right of Canada, 2002

Cat. No. M92-28/2001EISBN 0-662-31120-5

Aussi disponible en franais sous le titre :Les systmes photovoltaques : Guide de lacheteur


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1

Table of Contents

About This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1. What Is a Solar Electric or Photovoltaic (PV) System? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

What Is PV? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3How Does It Work? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3The Three Types of PV Power Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2. What Photovoltaics Can Do for You . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7The Advantages of PV Power Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7The Limitations of PV Power Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3. Photovoltaics at Work in Canada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Cottages and Residences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Power for Remote Lodges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Mobile and Recreational Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Photovoltaics in Agriculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15A PV System to Suit Your Particular Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4. Buying Your Photovoltaic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Be Prepared . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Where to Find PV Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Choosing a Dealer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Making a Decision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5. Installing and Maintaining Your Photovoltaic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Mounting the PV Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Housing the Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6. Estimating Your Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Step 1. Estimate Your Power and Energy Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Step 2. Make a Rough Evaluation of PV System Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

7. Sizing Worksheet Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Example 1. Summer Cabin Power System The Smiths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Example 2. Year-Round Remote Residential Power System The Wongs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

8. Technical Information on Photovoltaic System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35PV Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35The Electric Characteristics of PV Modules: The Current-Voltage (I-V) Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Other Components in PV Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Appendix A: Worksheet to Evaluate System Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Step 1. Estimate Your Power and Energy Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Step 2. Make a Rough Evaluation of PV System Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Appendix B: Typical Loads. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Typical Power Ratings of Some Common Appliances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Appendix C: Energy-Efficient Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Comparison of Typical Lighting Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Learn More About Solar Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Reader Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47


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The information in the followingpages is for prospective buyers ofphotovoltaic (PV) systems for use

in the following: remote cottages and

residences;

recreational and mobileapplications;

agricultural applications;

remote lodges; and

remote lighting applications.

The purpose of this guide is to

help you determine whether a PVsystem is a suitable option for youin providing electrical power forone or more of the above uses. Itdescribes typical and innovativePV systems, provides examples ofsuccessful Canadian installationsand answers some of the ques-tions you should ask yourselfbefore approaching a PV dealer(as well as questions a dealershould be able to answer).

Each section of this guide isdivided into short, easy-to-readsubsections. This format allows

you to browse by topic or readthe guide from cover to cover.Several forms are included tohelp you estimate your powerand energy needs.

Once you have read this guide,you should know enough aboutPV systems to consult dealers and,with them, evaluate the best PVconfiguration to meet your needs now and for the future. This

guide provides only estimates andis not intended to replace thetechnical expertise required forthe detailed design and installa-tion of a PV system. Nowhereshould you construe that thisguide recommends or promotesany specific products.

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About this Guide


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What Is PV?The term photovoltaic, com-monly referred to as PV, is derivedfrom a combination of photo,the Greek word for light, andVolta, the name of the Italianphysicist, Alessandro Volta, whoinvented the chemical battery in1800. The PV effect is the directconversion of solar energy intoelectricity. This process does notgenerate heat like solar domestichot water or solar pool heatingsystems do. It also differs from

the process used in solar thermalpower plants, where concentratedsolar energy is used to producesteam that activates a turbineconnected to an electric genera-tor. PV power systems do nothave any moving parts. They arereliable, require little mainte-nance and generate no noiseor pollutants. PV systems aremodular the building blocks(modules) come in a wide range

of power capabilities, from afraction of a watt (e.g. solarwatches and pocket calculators)to more that 300 W. Modulescan be connected to achievethe power that your applicationrequires. Some demonstrationPV power plants have severalmegawatts of power, althoughmost installed PV systems aremuch smaller.

How DoesIt Work?PV cells are normally fabricatedusing special semiconductormaterials that allow electrons,which are energized when thematerial is exposed to sunlight,

to be freed from their atoms.Once freed, they can movethrough the material and carry an

electric current. The current flowsin one direction (like a battery),and thus the electricity generatedis termed direct current (DC).

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1. What Is a Solar Electric or Photovoltaic (PV) System?

A PV module converts sunlight directly into electricity.

For applications that require electricity during overcast periods, batteries ensurethat the PV system is autonomous.


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The energy generated by PVmodules can be used immediatelyor stored in batteries for later

use. Normally, the excess energygenerated in autonomous PVsystems during sunny periods isstored in batteries. The batteriesthen provide electricity at nightor when there is not enough solarradiation. For these applications,the number of watts in the arrayand the capacity of the batteriesare carefully sized to give opti-mum performance.

Some autonomous applications,such as water pumping, oftenhave no need for batteries. Wateris pumped when the sun shinesand is stored directly in a reser-voir or a tank that is installedat a higher level for later useby gravity feed.

Other PV systems convert theelectricity into alternating current(AC), feed excess electricity intothe grid and draw out electricity

at night or when the solar radia-tion is low. These systems arereferred to as grid-connected,grid-tied or net-metered.

The Three Typesof PV Power

SystemsThe three typical configurations ofPV power systems are autonomous,hybrid and grid-connected.Autonomous and hybrid powersystems are used in stand-aloneapplications. They are not con-nected to the main utility gridand are often used in remote areas.

AutonomousAutonomous systems rely exclu-

sively on solar energy to meet aneed for electricity. As mentionedin the preceding, they mayincorporate batteries whichstore energy from the PV modulesduring the day for use at night

or in periods of low solar radia-tion. Alternatively, they maypower the application entirely,

with no need for batteries(e.g. water pumping). In general,autonomous PV systems are themost cost-effective source ofelectrical power. You may,however, decide to choose ahybrid PV system because ofthe environment in which itwill operate or because youneed a system that operatesindependently and reliably.

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AutonomousPV systemwithout batteries.

AutonomousPV systemwith batteries.

Hybrid PV system.

Autonomous PV Systems Hybrid PV System

Generator


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HybridHybrid systems, also used instand-alone systems, consist of PV

modules and a wind and/or fuel-fired generator. A hybrid system isa good option for larger systemsthat need a steady power supply,when there is not enough sun atcertain times of the year, or if youwant to lower your capital invest-ment in PV modules and storagebatteries.

Grid-ConnectedGrid-connected PV power systems

are part of the movement towarda decentralized electrical network.Power is generated closer towhere it is needed not solely bycentral power stations and majorhydro stations. Over time, suchsystems will reduce the need toincrease the capacity of trans-portation and distribution lines.

A grid-connected system gener-ates its own electricity and feeds

its excess power into the utilitygrid for later use. This does awaywith buying and maintaining abattery bank. You can still usebattery banks to provide backuppower when the grid goes down,but they are not required.

Smaller systems have a box a small grid synchronous inverter mounted on the back of eachpanel. Larger systems have onelarge inverter, which can handlemany panels (as in a stand-alonesystem). Both types convert DCpower output into AC power. Thenthey synchronize this output withthe grid to slow down the electri-cal meter. They can even turn themeter backward. If the PV outputis less than the load consumption,the meter slows down.

If PV output exceeds the loadconsumption, the meter turns

backward, and a credit is accumu-lated. This credit can be drawnout of the utility when the sun isnot shining. In essence, the grid

acts like a limitless battery bank.In most parts of Canada, permis-

sion from the local utility isrequired in order to back feedpower into the grid.

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Water oxygenation compressorsand water pumps are examplesof PV systems that function with-out batteries. Photo courtesy ofEnvironergie Qubec Inc.

Remote residences or cottages canhave access to electricity withoutextending the grid. Photo courtesyof Solener Inc.

Centralized and distributed grid-connected PV systems.

Grid-Connected PV Systems


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A large portion of the cost ofa grid-connected PV system ismanufacturing the PV modules

themselves. Significant decreasesin manufacturing costs haveoccurred in recent years, withfurther decreases expected in thefuture. This kind of PV system isthus becoming more affordable.In some urban areas in warm cli-mates, the cost per kilowatt-hourof electricity from grid-connectedPV systems is competitive withthat of other electricity-generatingsystems. In areas with less solar

radiation, the cost-effectivenessof this type of PV system is stillmarginal. But there is a potentialfor peak power savings in areaswhere air conditioning causes apower peak in the summer. Thereare also system savings wherethe PV modules can replace thetraditional roofing materials forbuildings or the cladding materialthat is normally used in buildingfaades. These material savingsare making the costs per kilowatt-hour from grid-connected PVsystems increasingly competitive.

Decentralized small home systemsalso hold some potential forgrid-connected PV systems, butthe costs will have to be reducedfurther in order to compete withthe low electricity rates now avail-able in most parts of Canada.Note, however, that PV electricity

is green energy and, as such, isworth a premium. Even thoughthis value is subjective, it shouldbe expressed in numbers by thePV systems designer. For exam-ple, how much is the avoidedpollution of conventional sourcesworth and how much is theavoided distribution cost worth?

To install a PV system, you mustpay the capital cost of the systemand amortize this cost over time.In contrast, where there is a utilitygrid, you pay for the electricity

used and not a lump sum for thegenerating facility. The costs ofthe PV system may appear to bea burden because the electricitythat the system generates may costmore per kilowatt-hour than whata utility charges. But using a PVsystem may also be considered alifestyle choice, similar to choos-ing between a fuel-efficient car ora gas-guzzling sport utility vehicle.

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This house in Edmonton, Alberta, is equipped with a 2.3-kW system that isconnected to the local power utility. About 2500 kWh are produced each year.The investment cost in 1995 was $28,000.


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Perhaps you need reliablepower in a location that isnot connected to an electrical

grid. In this case, photovoltaicsmay be the best and mostcost-effective solution. Manylocations in Canada that have adry continental climate have thesame number of daylight hoursas some Mediterranean countries.A photovoltaic (PV) system usedduring the summer in Canadacan take advantage of substantialdaily amounts of solar energy.Contrary to what many people

think, PV systems convertsunlight into electricity moreefficiently at lower temperatures.However, the winter months inCanada provide half the hoursof sunlight as in summer. Muchof Canada experiences highwinds in the winter, which canmake a wind generator a logicaladdition to the system. Fuel-fired generators are then usedonly for backup.

Among other things, you can usePV energy to:

supply power for lights,

radios, televisions, pumps andother appliances in cottagesand residences;

power electric fences, waterpumps and other devices inagricultural operations;

run water-pumping and circu-lation systems in game fishingand aquaculture facilities;

provide reliable electric power

for wilderness lodges andhunting and fishing camps;

recharge or maintain chargeof batteries for recreationalapplications such as recre-ational vehicles and sailboats;

power portable devicessuch as laptop computers;

power exterior lighting;

provide reliable powerfor many commercialapplications; and

lower your monthlyutility bills.

The Advantagesof PV Power

SystemsUsers of PV power systemsappreciate their quiet, low-maintenance, pollution-free, safeand reliable operation, as well asthe degree of independence theyprovide. Why else should youconsider buying a PV system?If you are some distance from anelectrical grid, it may be cheaperto generate your own powerrather than pay to extendtransmission lines from thegrid. Diesel, gasoline or propanegenerators are the conventionalalternatives, but many peoplefind them noisy, polluting andcostly to run and maintain. Italso makes little sense to turn ona 5-kW generator to power a few100-W light bulbs. PV systemsreduce the negative aspects ofgenerators by using them only

as a backup.When capital cost is an issue, orwhen photovoltaics alone arenot enough to replace an existinggenerator, you can use a windgenerator as part of a hybrid PVsystem, thus reducing the use ofthe generator. Such an intermit-tent charge system is more efficientthan a generator running continu-ously at low load. In addition tosaving fuel and lowering mainte-

nance costs, you will increase thegenerators life span. Also, sincethe PV panels and battery banksare modular, you can expand thePV system gradually as yourbudget or needs increase.

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2. What Photovoltaics Can Do for You


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The Limitationsof PV Power

SystemsIt is important to realize that PVpower systems are capital inten-sive from the buyers perspectiveand are expensive when com-pared with the low price of utilitypower in Canada. You shouldtherefore reserve the electricpower produced by PV modules,an inverter and a storage systemfor your most energy-efficientappliances, tools, lights, etc.

Although it is technically possi-ble, heating with photovoltaics isgenerally not recommended. Youcan easily and more efficientlycollect heat with a solar thermalsystem. A solar water heater gen-erates more hot water with lessinitial cost than any PV-poweredheater.1 Also, for cooking, it is

generally more cost-effective andconvenient to use a stove thatoperates on propane or natural

gas rather than solar electricity.Autonomous PV-powered homesand cottages often rely on woodcookstoves for cooking and spaceheating. Refrigerators are becom-ing more energy efficient, so thecost of operating them with PVpower is now feasible. Extremelyenergy-efficient refrigerators andfreezers are, unfortunately, stillexpensive, however, they can behad through PV dealers.

From an economic point of view,first consider investing in energy-efficient electric appliances, andthen size your PV system basedon actual consumption. Forexample, using compact fluores-cent lights will reduce yourelectrical consumption forlighting by 80 percent.

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1For more information, obtain a free copy of Solar Water Heating Systems: A Buyers Guide from Natural Resources Canada.Call 1 800 387-2000 toll-free, or visit the Web site at http://www.canren.gc.ca.


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The use of photovoltaic (PV)technology is increasing rapidlyin developed and developing

countries. Although the CanadianPV industry has also expandedsignificantly over the past decade,the use of photovoltaics inCanada is still relatively limited.This is partly because of Canadaslow utility rates, but the followingcommonly held myths are alsoresponsible:

Myth: There is notenough sunlightin Canada.

Myth: Solar electrictechnology is notefficient in acold climate.

Myth: Photovoltaicsis not a proventechnology.

Myth: PV systems aretoo expensive.

Thousands of PV systems inmyriad applications throughoutCanada and millions throughoutthe world today have debunkedthese myths. Although conditionsin Canada pose a special chal-lenge to the use of photovoltaics,

an appropriately designed PVsystem can give you reliablepower to most remote sites. Inthe following pages, examplesof actual, cost-effective PVinstallations across the countrywill demonstrate what photo-voltaics can do for you.

Cottages andResidencesIncreasingly, Canadian homeown-ers are using PV systems to powerlights and appliances in remotecottages and residences that arenot connected to a utility grid.Like these homeowners, youllappreciate the quiet, low-mainte-nance, safe and pollution-freeoperation of a PV system, as wellas its versatility and reliability.In general, PV systems are cost-competitive for cottages and

residences that are more thanseveral hundred metres from theelectricity grid. But they are notyet a cost-competitive alternativein locations that have direct accessto power from the grid.

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3. Photovoltaics at Work in Canada

Example 1. A TypicalAutonomous PV Applicationfor a Remote Cottage

A cottage, located away from the

power grid, uses photovoltaics to

power several fluorescent direct

current (DC) lights, some halogen

lights and a DC water pump,

which supplies water to the resi-

dents. A stove and a refrigerator

run on propane fuel. No inverter is

needed, but one can be included

any time if alternating current (AC)

loads are added.

The cottage is equipped witha PV system that consists of

the following:

two 75-W solar modules

(150 W of photovoltaics);

a 20-A (ampere) regulator;

a load/fuse panel;

a bank of batteries; and

a second PV system that

powers a small, exterior DC

light with an 8-W panel and

an independent battery.

The cottage is used primarily on

weekends and during vacations,

which explains the large battery

capacity compared with the total

area of PV modules. This allows

more energy to be availableduring two days of occupancy,

and the PV modules recharge the

batteries over the remaining five

days of the week. This system

has been functioning maintenance-

free since 1997.Photo courtesy of Cimat enr.


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Example 2. An AutonomousPV System Powers a SummerResidence on an Island on

the St. Lawrence River nearMontral, Quebec

Major power-line damages inQuebec have occurred twice in five

years, the most recent being the

severe ice storm of 1998. For one

of its customers that has an island

summer cottage, Hydro-Qubec

decided to provide a stand-alone

PV system instead of maintaining

a 200-m power line between the

island and the mainland.

The average amount of electricity

needed to run this cottage is

5.5 kWh/d (very low by Canadianstandards), mainly during the sum-

mer. The load consists of lights,

household appliances, power tools,

water and pool pumps, an alarm

system, etc. This load is expected

to be 75 percent less during the

winter, when only exterior lighting

and the alarm system are active.

Three possible solutions were

analysed: the replacement of the

overhead power line, a submergedcable and renewable energy. Due

to Canadian Coast Guard regula-

tions, the new overhead line would

have to be at least 1015 m higher

than the one previously installed.And it would have been expensive

for Hydro-Qubec to install a

submerged cable, given the high

levels of polychlorinated biphenyls

(PCBs) in sediments of the

St. Lawrence River. In November

1997, Hydro-Qubec decided to

evaluate alternative options. A PV

stand-alone system was preferred

to a wind generator, due to the

potential for low winds in the

Montral region in the summer.

Finally, a solar-only PV system

was chosen because the electricity

needs in the winter were about

a quarter of those in the summer.

This would avoid the trouble of

maintaining a fuel-fired generator.

The solar-only PV system consists

of the following:

twelve 90-W PV modules, with a

total capacity of just over 1 kW in

12 VDC (volt direct current);

the existing Hydro-Qubec pole

used for the support structure;

a separate, ventilated outbuilding

provided by the owner for the

batteries and system components

(not always necessary);

a 40-A solar controller;

a 2.5-kW, 120-VAC (volt alternat-

ing current) pure sine-wave

inverter with a surge capacityof 8 kW; and

a 1595-Ah (ampere-hour),

12-VDC battery bank.

The batteries offer seven-dayautonomy when the sun is not

shining, based on the expected

daily load. However, the home-

owner knows about the need to

monitor the use of electricity when

overcast or rainy conditions are

forecast. Therefore, a meter was

installed to provide instant infor-

mation on the reserve capacity

remaining in the battery bank

(based on current load consump-

tion) and on the charge rate fromthe PV array.

Hydro-Qubec financed the instal-

lation of the PV system, even

though the cost of solar electricity

produced was more than 10 times

the regular cost charged by the

utility (about 60 per kWh versus

6 per kWh). The savings on

electric-line maintenance justify

the cost. Hydro-Qubec also

planned funds for replacing systemcomponents after their lifetime

(e.g. 25 years for the PV modules).

After two seasons of use, both

Hydro-Qubec and the home-

owner are satisfied with the

performance of the PV system.

It can handle the heavy use of

a washing machine, a toaster,

lights, pumps, etc., during week-

ends when all five bedrooms are

filled by up to all 16 members

of the family.


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Power forRemote Lodges

Owners of remote fishing lodgesmay find that a properly designedPV hybrid system is economicallyattractive, be it PV-diesel, PV-windor a combination of the two. The

high cost of diesel generation atremote sites often prompts the

owners to look for alternatives,namely, renewable energy tech-nologies. In many instances, aPV-diesel hybrid system provesattractive because it is cost-

effective, simple and reliable.During periods of little sunshine,

the use of the diesel generator canbe reduced by drawing power froma bank of batteries and by runningthe generator only when thebatteries are low.

11

Example 3. A Solar-DieselHybrid System at TarryallResort, Catherine Lake(Near Keewatin), Ontario

Tarryall Resort operates from April

to October. The resort consists of

seven cottages and a main house

that can accommodate up to a

dozen people. The cottages areequipped with propane-powered

appliances and lighting. Electricity

is used year-round in the main

lodge to power a full range of

appliances, including a clothes

washer, a large freezer, a water

pump, televisions, lights and

power tools.

The resort is located six kilometres

from the electrical grid. In 1980

the owners considered connectingto the utility grid, but the cost was

estimated at more than $80,000.

The owners instead decided to

improve the resorts energy effi-

ciency. They switched to more

efficient 12-V fluorescent lights,

put a smaller motor in the water

pump, installed timers on the exte-

rior lights and moved their freezer

outdoors in the winter. Using more

efficient lights, in particular, has

had a significant impact on daily

energy consumption.

The resorts electrical generatingsystem consisted of two diesel

generators (a 7.5-kW main genera-

tor running 24 hours a day and

a 3.0-kW backup generator). The

high cost of diesel prompted the

owners to investigate a solar-diesel

hybrid system.

In 1986 the owners installed a

hybrid system that included the

following:

a 564-W PV array;

a bank of 24 two-volt,

deep-cycle batteries; and

the existing 7.5-kW diesel

generator.

The resorts diesel consumption

has been considerably reduced

since the PV-diesel hybrid system

was installed. The generator is

used once every three or four days

for about 10 hours to recharge thebatteries. Previously, it had con-

sumed fuel continuously, while

supplying only about one quarter

of its nominal capacity. The PV

panels contribute about 15 percent

of the lodges energy require-

ments. They also permit a gentle

trickle charge of the batteries at

the end of the charging cycle,

thereby extending battery life and

increasing the systems efficiency.

Because the diesel generator is

used more efficiently in the hybrid

system configuration than it would

be on its own, it needs fewer oilchanges and less frequent major

overhauls and repairs. Also, the life

span of the generator is extended.

During its first year alone, savings

in fuel and maintenance charges

totalled about $7,000.

Despite the high up-front cost

($36,000 in 1986), the hybrid

system paid for itself within

six years. Tarryalls owners are

pleased with their PV system and

particularly enjoy the quiet, cleanoperation a major improvement

over the constant noise of a diesel

generator. They have since added

four PV modules, increasing the

capacity to 752 W. This further

reduced the need for diesel-

generated electricity. The original

lead-acid batteries were still being

used in 2000, after 14 years of

service. Tarryalls owners were

so satisfied with photovoltaics

that they also equipped each

of the seven cottages with an

autonomous PV lighting kit

(one module with one deep-

cycle battery).


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12

Example 4. A Hybrid PVSystem at the Warden Stationon Huxley Island, Gwaii

Haanas Marine ConservationArea National Park Reserve

Located in the Moresby Island

archipelago in British Columbia,

Huxley Island serves as a registra-

tion office for visitors to Gwaii

Haanas Marine Conservation Area

National Park Reserve. These

include scientists visiting the area,

which is dedicated to environmen-

tal conservation. The camp has a

75-m2

building with a full kitchen,bunks for four people and an office

equipped with a satellite tele-

phone, VHF radios and computers.

To meet these electricity needs,

park administrators chose a hybrid

stand-alone PV system. Its advan-

tages over a continuously operated

generator include less engine

maintenance, a lower need for

refuelling and reduced noise.

A power system installed in 1996

consists of the following:

a 600-W solar array using eight

75-W modules;

a 4.0-kW sine-wave inverter;

a 38-kWh lead-acid

battery bank; and

a 5.0-kW gasoline

generator.

To make installation easier, all

electrical components were

pre-assembled and wired on a

1.3-m2 board before shipment.

The distributor also provided a

waterproof aluminum outdoor

cabinet for the batteries andpower equipment. It was installed

directly behind the living quarters.

A state-of-charge battery display

and a remote control for the

inverter and generator were

installed on an interior wall of the

building for the convenience of

park staff.

The integrated power system is

completely automated. The system

provides the bulk of the power

to the loads, with the generator

available for backup. In the event

of poor weather or excessive loads,

the generator is programmed

to start when the battery bankreaches 50 percent of its nominal

capacity. This way, the batteries

are charged before a potentially

damaging low-battery condition

is reached.

Photo courtesy of Soltek Solar Energy Ltd.


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Mobile andRecreational

ApplicationsChances are that you are alreadyrelying on PV technology to helpyou keep track of time, balanceyour budget or enliven your leisurehours. Many products such aswatches, calculators and toys havebeen PV-powered in an inexpen-sive, reliable and convenient wayfor many years. Equipped withtiny PV cells that produce powereven in dim lighting, theseconsumer products eliminatethe need for costly batteries thatneed to be frequently replaced.

Nowadays, versatile PV powerpacks are also used to powerlarger consumer products. Theyare available in a range of sizes,from fractions of a watt to over100 W. Power packs can also behooked up in series or parallelconnections to serve various

power needs. They can be usedas either a direct power sourceor as a battery recharger. Theseconvenient PV systems powereverything from radios, cassetterecorders and cameras to lawnornaments, walkway lights andbatteries for sailboats and gliders.The clean and noiseless opera-tion of PV systems for manyrecreational applications is asignificant benefit.

In recreational vehicles andelectric-powered boats, PV panelscan help recharge batteries. Themain advantage of a PV system isthat it will, at the least, maintainthe state of charge of batteries onboard even during extendedperiods of time when you arenot using the equipment.

13

Many owners of recreational vehicles are already using PV technology.Photo courtesy of Rozon Batteries Inc.

People working in the field withportable computers appreciatethe autonomy that PV offers.Photo courtesy of Midnight Sun

Energy Ltd.


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14

The Power SystemAs 5.5-W panels are common,

the team needed at least two

panels, which provided extra

power to compensate for bad

weather or additional loads. The

PV system had the following

characteristics:

Main Advantages of the PV System

Primary lithium batteries are

generally used for this kind of

expedition. An estimated twenty

10-Ah lithium batteries would have

been needed, for a total cost of

$6,000 and a weight of 12.5 kg.

This alternative was rejected due

to its cost and weight.

Another alternative would have

been to carry a small gasoline

generator. The smallest, lightest

generator available was a 300-W

generator that weighed 18 kg.

Apart from its weight, fuel would

have had to be carried and han-

dled. Also, fumes and noise from

the generator would be unpleas-

ant, and starting the engine in

a cold environment would be

difficult. The team rejected this

alternative as impractical.

PV energy represented the most

economical, reliable, practical

and environmentally friendly way

to generate electricity for such an

expedition not to mention

the lightest.

Example 5. Photovoltaics for a South Pole Expedition

Explorers Bernard Voyer and Thierry Petry were the first North Americans

to reach the South Pole by ski unassisted. Each had to pull a 170-kg pulka(a toboggan-like sled) over an uneven surface of stratified ice swells. Sunlight

was available 24 hours a day during their expedition; however, the usable

sunlight hours per day was between two and nine hours (or 5.5 hours per

day on average).

Electricity Need

The explorers used a PV system to power a satellite telephone under the

extreme climatic conditions. This system also served as a backup for the

lithium batteries for a video camera. The PV system was designed to power

the following equipment:

Converted to Wh per day

satellite telephone: 60 W (8 min/d) 60 W x 8/60 8 Wh/d

portable computer: 42 W (15 min/d) 42 W x 15/60 10.5 Wh/d

positioning system: 0.5 W (24 h/d) 0.5 W x 24 12 Wh/d

video camera: 20 W (12 min/d) 20 W x 12/60 4 Wh/d

Average total daily demand: 34.5 Wh/d

As mentioned above, sunshine was usable for 5.5 hours a day on average,

so the team needed 6.3-W worth of PV modules (34.5 Wh/d 5.5 h/d) daily.

Photo courtesy of Bernard VoyerExplorateur Inc.

installed PV power: 2 x 5.5 W storage capacity: Lead-acid 12 V, 9 Ah

Nickel-cadmium 12 V, 5 Ah

total weight: 5 kg

The conditions of operation were as follows: average temperature: -15C to -33C (December/January)

The system cost $600.


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Photovoltaicsin AgriculturePV systems are particularly wellsuited where a small amount ofenergy in remote locations isneeded for agricultural applica-tions, such as electric fencing,water pumping for irrigation orstock watering, pond aeration, etc.

Electric FencingPV-powered electric fencing ispopular in Canadas westernprovinces, chiefly in northern

pastures where land is open forcattle. Several cattle ranchersin northern Alberta and BritishColumbia have installed PV mod-ules to charge the batteries ofstandard electric fencing. Thesebatteries will never run down.PV-powered electric fencing notonly eliminates the cost andinconvenience of regular visits tocheck batteries, but also costs lessthan barbed wire fencing, which

is the other alternative to con-ventionally powered electricfencing. More and moreranchers and

farmers in Canada are finding

that PV systems, which can runall summer with no need for ser-vicing, are a practical alternativefor their remote fencing needs.

Water Pumping for StockWatering and IrrigationWater pumping is one of themost attractive uses for PV sys-tems. In agriculture, the demandfor water is greatest when the

weather is hot and dry, preciselywhen the most solar energy isavailable. Simple non-storage

types of PV systems are idealfor many irrigation applicationswhere crops can do without waterwhen the sun is not shining.In situations where irrigation isneeded independent of weather,power stored in the form ofpumped water, rather than incostly storage batteries, makesPV-powered irrigation systemseconomically attractive.

Today, several million hectaresof remote grazing land in Canadaare not being used because thecosts of pumping water for stockwatering by conventional meth-ods outweigh the grazing benefits.For many Canadian ranchers andfarmers, PV-powered pumpingsystems offer a cost-effectivesolution.

15

PV-powered electric fencing savesboth time and money for ranchersand farmers. Photo courtesy ofthe Agricultural Technology Centre(formerly the Alberta FarmMachinery Research Centre).

Stock watering using a PV-powered waterpumping system from a pond to preventcontamination of the source. Photo courtesyof Sunmotor International.


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A PV Systemto Suit Your

Particular PowerRequirementsStandardized PV systems arebecoming more and more com-mon. However, many PV systemsin Canada are custom-designed totake into account the particularneeds of the user and the charac-teristics of the site. Therefore, youshould not necessarily expect tobuy such a system off the shelf

as you would a diesel or gasolinegenerator. Rather, you willprobably have to consult PVequipment suppliers for a systemthat is right for your needs.

The telecommunications industryand the Canadian Coast Guardused PV power systems earlyon for remote telecommunica-tions repeater stations, beaconsand navigational aid systems.Their expectations for reliabilityhelped the PV industry developquality products and improvedesign tools.

Small PV lighting packagesare available from dealers. Forski hills, lighthouses, isolatedstretches of highway and off-gridcommunities and businesses,PV-powered lighting providesa practical, affordable solutionto remote lighting problems.

16

A small PV module is used topower a trail indicator at night atMont-Tremblant, Quebec. Photocourtesy of TN conseil inc.

This PV-powered aquaculture facility ison an island off Canadas west coast.

The limited powerneeds of remotemonitoring systemsare easily met bysmall PV systems.This exampleshows a gaswellhead.

Early Uses for PV in Commercial Applications

Due to the remotenessof repeater stations,telecommunicationshas been one of thefirst and remains

one of the most popu-lar applicationsfor PV systems.Photo courtesy ofNorthwestel Inc.

The Canadian CoastGuard has been usingthousands of PV-powered buoys alongcoasts for many years.


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Be PreparedBefore approaching a dealer,you should consider your powerrequirements and the type ofphotovoltaic (PV) system that willsuit your needs and your budget.

The following are typicalquestions that you should askyourself. Be prepared to supplythe following information asprecisely and clearly as possible:

What is the application?

What needs to be powered?

Are my loads as efficient aspossible?

How much power (wattage)and/or energy (watt-hoursper day) is required?

What is the energy-usagepattern (e.g. hour per day,days per week, seasonal use)?

Do I need battery storage?

Do I want an autonomous,

hybrid or grid-connectedsystem?

Do I want to start small andadd modules in the future?

A first step in any design or costevaluation is to assess your load:i.e. what do you expect the PV

system to power? Section 6,Estimating Your Needs (page24) is intended to help you evalu-ate the options. A worksheet isprovided in Appendix A (page 40)to help you estimate and choosea suitable PV system. This work-sheet is intended to guide you inestimating your power and energyneeds, evaluating the PV arraysize and estimating the batterycapacity that you require.

Note that this exercise is optional.However, you should at leastprepare a list of all appliancesand other electrical equipmentthat the PV system might powerand estimate their time of use(see Step 1 in the worksheetprovided in Appendix A). Themore detailed and accuratethe list, the easier the sizingof your PV system will be for

you or your dealer.

Where to FindPV SystemsApart from some specific con-sumer products or special sales,PV power systems are just begin-ning to be widely available inhardware or department storechains. Dealers of recreationalvehicles, boats and electricfences may sometimes offer PVsolutions adapted to their prod-ucts. However, for most customapplications, you will need tofind a PV dealer. Generally, this

gives you the advantage of betterservice, since such dealers shouldhave a good understanding ofthe technology and can help youselect, size and design the systemthat best suits your needs. Thereare many distributors and dealersof PV systems in Canada, andthe industry network is growing.Some of these companies special-ize in different types of systems,e.g. communications, home

energy systems, consumerproducts, agricultural andunique design.

To find PV distributors or dealers,contact the Canadian SolarIndustries Association, NaturalResources Canada (see LearnMore About Solar Energy onpage 46) or consult the YellowPages. You may also wish toobtain a referral from a satisfied

customer.

17

4. Buying YourPhotovoltaic System


20/49

Choosinga DealerA PV system should be designedfor the best efficiency and cost-effectiveness. It is wise to consulta professional at the design stage.Most dealers offer design andconsultation services as well as PVmodules and balance of systemcomponents such as batteriesand inverters. Some companiesconcentrate on industrial applica-tions; others specialize inresidential and commercial sys-

tems. Make certain that the dealeryou select has proven experiencein designing and installing thetype of system you want. Askto see some systems that havealready been installed, or talkto someone who has bought asystem that is similar to whatyou want.

A responsible dealer will askyou questions about your power

consumption, lifestyle and needsbefore designing your PV system.If you cannot afford as many PVmodules as you would like butintend to add to the system later,make sure that the systemdesigner knows this.

The PV dealer should offer awarranty on parts and labour.The warranty for PV modules

can now be as much as 25 years,depending on the type of mod-ules and manufacturers policies.Most modules will performreliably for a longer period.Check which warranties thedealer offers on the other compo-nents (electrical and mechanical)and on the labour. Moreover,check on follow-up service avail-able from the dealer. In general,take the same sort of precautions

when buying a PV system thatyou would when buying a newappliance.

Following is a list of items toconsider in evaluating a dealersproduct and service. Use it whenchoosing a dealer.

design/sales experience

knowledge of energyefficiency

area of expertise product quality

product warranty

installation service

follow-up service

price

Making aDecisionOf course, cost is always impor-tant in any purchase decision.The economics of PV systemsare often quite site-specific. Ingeneral, conventional energysources tend to have low initialcapital costs but have high oper-ating and maintenance costs. Incomparison, PV systems havehigher initial capital costs buthave lower maintenance andoperating costs. Thus, to evaluate

the economics of a PV system,you must consider the totalcosts of competing alternatives including capital costs, fuel costsand maintenance and operatingcosts over the life of the system.

For off-grid commercial opera-tions that have labour andmaintenance costs, PV systemscan often be economical. Forindividual homeowners, who

usually do not count theirown labour for operation andmaintenance as a cost of runninga generator, the initial cost of aPV system may appear to behigh. However, for many homeand cottage owners, the non-economic benefits of PV systems in particular, their reliability andquiet, non-polluting operation far outweigh the extra costs.Especially in summer, owners of

PV systems appreciate that theycan enjoy the sounds and smellsof nature without interferencefrom their power system.

18


21/49

Of course, the cost of a PV systemdepends on what it includes. Asimple autonomous system for a

cottage or cabin, suitable for pow-ering a few lights, a water pumpand radios (e.g. 40100 W) cancost from $700 to $2,000. Larger,hybrid systems that are suitablefor year-round residences orlodges (2001500 W) can costfrom $5,000 to $30,000.

In considering the economics ofPV systems, it is important torealize that the costs of these sys-

tems are steadily declining. ThePV industry, like the computerindustry, is continually evolving.

Improvements in PV cells, batter-ies and other system componentsand in system design are resulting

in lower prices for PV systems.One of the most attractive fea-tures of PV systems is that theycome in modules. The PV compo-nent of a hybrid system can besized to suit your budget: as pricesdecline and/or your savingsincrease, you can add more PVpanels and decrease your relianceon the backup generator. If youdo not already have a generator

and are considering a solar-onlysystem for a cottage or sailboat,you can start with a small system

to power a few essential appliancesand upgrade it as your financesallow. Because PV systems last

25 years or more, they represent asolid investment. By the way, theprice for used panels is not muchless than that for new panelsbecause they remain in perfectcondition for years.

The following form will helpyou compare the advantages anddisadvantages of an autonomousor hybrid PV system with conven-tional diesel, gasoline or propane

alternatives.

19

PV System Purchase Decision Factors

Decision Factors Option A: Autonomous Option B: Hybrid PV Option C:PV System System Conventional System

(diesel, gasoline orpropane generator)

Capital Costs

Operating Costs

Maintenance Costs

Other Factors

(e.g. noise, pollution,

reliability, flexibility for

expansion, refuelling

needs, your time)


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One major advantage of photo-voltaic (PV) systems is that theyare relatively simple to install and

maintain. For large or complexsystems, PV companies usuallyhelp with installation andmaintenance.

InstallationYour supplier should give youany relevant system documents.Carefully read all of the manufac-turers recommendations. As withany electrical system, safety is

important. You must obtain anynecessary building and electricalpermits and ensure that the sys-tem is installed according to code.Qualified people should installthe system. If you have a grid-connected system, installationwill involve the local utility.

Wiring must be properly installedto avoid shocks, fires and otherhazards. The main considerationis the type and size of wire. Forexample, the array wiring mustbe suited for outdoor use and besized properly in order to carrythe peak current. As a result, youwill normally need larger wiresfor low-voltage systems (12 Vcompared with 120 V) to preventoverheating and voltage loss inthe wires. Consult a professionaldesigner or installer to select theproper wires. You will also need

the services of a professionalinstaller to:

properly fuse the systemfor protection against shortcircuits in the wiring orappliances;

ensure that the system isproperly grounded and pro-tected against lightning; and

include switches between allcomponents of the systemthat need to be isolated forany reason.

Mounting thePV ArrayPV modules are designed to beinstalled outdoors without addi-tional protection. A mountingstructure must be constructed tosupport the modules in all weatherconditions. Many manufacturerssell support frames designed tohold their modules; you maydecide to build your own.

Factors to be considered in mount-ing the array include orientation,safety, structural integrity andlocal codes. The PV array shouldbe mounted so as to take fulladvantage of the sunlight. In the

northern hemisphere, it shouldface south; true south is best, buta deviation of 15 degrees east orwest will not affect performancevery much. Very large installationscan be mounted to track the suneither automatically or manually(see Technical Information onPhotovoltaic System Componentson page 35). In most cases, themounting is fixed at one angle(a right angle to the sun at noon),but can be adjusted according tothe season.

Select a site where the arraywill not be shaded at any point

during the day. A shadow on thearray can substantially cut poweroutput. If possible, ask your neigh-bours if they plan to add trees orbuildings adjacent to your prop-erty. Easements and restrictivecovenants (for definitions, seethe glossary on page 44) aretwo types of legal instruments.When used for solar applications,they provide certain guaranteesto property owners about their

access to sunlight. If access tosunlight concerns you, sucha written agreement may beworthwhile.

20

5. Installing and Maintaining Your Photovoltaic System

Array orientations showingsuggested tilt angles for summer,spring and fall and winter usein southern Canada.

Summer

Spring

and Fall

Winter

45

35

60


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Depending on the array size andthe particulars of the site, the PVarray can be mounted on a roof,

a pole or the ground. In general,the large surface areas of the mod-ules create high wind loads onthe mounting structure, so thestructure must be designedaccordingly. Due to these highwind loads, ground-mountedinstallations require properfoundations. For small, ground-mounted installations,

foundations can be posts sunkinto the ground to anchor thearray support frame. The supportframe itself may be made of metalor wood. Modules are mountedso that the bottom of the array isabove the highest depth of snowlikely to fall. Make sure that thereis no bottom lip on the array so

that snow can slide off freely.You can use pole mounting forsmall systems (one to 12 modules)to ensure proper orientation or tolift them above potential sourcesof shade, such as buildings ortrees. The main advantages are nosnow buildup to shade the arrayand the potential to track the sun.

For many residences and cottages,roof mounting is an attractiveoption, particularly if the building

is under construction. The mod-ules should be mounted a shortdistance above the pitched roofand tilted to the optimum angle.Since PV modules work betterwhen the ambient air tempera-ture is lower, the free circulationof air around them will improvetheir performance. Elevating thearray will also prevent thebuildup of moisture and debrisbehind the modules. This buildup

could rot the roof and deterioratethe electrical connections. Forresidences and cottages with achimney, the array should bemounted in such a way that shad-ing from the smoke is avoided.

Wherever you choose to mountthe array, unless shading is a con-cern, try to locate it as close aspossible to the battery bank or tothe load (if there are no batteries).

This will lower wiring distancesand resultant power losses.

21

Ensure that your PV array will notbe shaded by neighbouring trees orother sources of shade.

Ground- and roof-mounted PV arrays.

Is Magnetic South Truly South?

Using a compass to help you orient your PV array so that it facessouth means that you will be relying on magnetic south instead oftrue south. It is better to use true south. In some parts of Canada, the

deviation of true south from magnetic south can be large enough toaffect the performance of your PV array. If your array is fixed (i.e. itwill not be tracking the sun) and you are unfamiliar with the devia-tion of the compass needle from true south at your location, ask anexperienced local dealer or installer for assistance.


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Housing theBatteriesYour choice of battery locationshould comply with the CanadianElectrical Code, whether youinstall the batteries inside or out-side. The location should also bedesigned to keep the batterieswarm (25C is best), because theircapacity decreases at temperaturesbelow 25C. This means that ifyou choose to locate your batter-ies in an unheated space, you willneed to insulate the area properly.

You will also need greater batterycapacity to compensate for thelosses at lower temperatures.Make sure that your supplierknows about the planned locationof your batteries.

The batteries and other equip-ment should be accessible formaintenance and inspection, butsafety must also be considered.Batteries may give off hydrogen

gas during charging and can bea source of electric shock, so theroom or area where they arehoused should be properly ventedto the outside and kept locked.

In addition, other electricalcomponents, which can also be asource of spark, should be kept

separately from the battery hous-ing. Do not locate batteries nearsources of heat or possible sourcesof open flame or spark. Finally,read all of the manufacturersrecommendations and warningsabout the safe and proper useand handling of batteries.

Inside LocationsBatteries located inside the livingspace should be properly vented

to the outside. For small cottagesystems with, for example, two12-VDC (volt direct current) bat-teries, you need a vent that is atleast 2.5 cm (1 in.) in diameter.Keep batteries separate from theliving space by housing them inspecial battery cases (with ventila-tion to the outside). For summer

cottages, keep batteries full ofcharge to prevent freezing inthe off-season.

Outside LocationsBatteries located outside of theliving space should be housed ina box or shed. In a very cold loca-tion, you can house the batteriesin a buried container for bettertemperature control. In all cases,batteries should be well protectedfrom the elements and be wellvented to the outside.

22

Battery housed in a shed.

BatteryShed

Vent

Insulation

Battery

BatteryChargeController

HeatedBuilding


25/49

MaintenanceAn important advantage of PVsystems is that they require littlemaintenance. The arrays them-selves are durable and reliable andneed little attention. The follow-ing summarizes the principalmaintenance that your systemwill need, but you may wish toask your dealer for a maintenanceschedule that is adapted to yourparticular system and location.

23

Unless you live in an extremelydusty area or have severe problemswith ice storms, you need to inspectthe wiring and general panel appear-ance only occasionally. If yoursystem has an adjustable mounting,you can carry out this routine main-tenance check at the same time asyou adjust the tilt angle of the array.When you adjust the angle of thearray for winter operation, snowloading is not a problem becausethe array is tilted steeply. If the

array becomes dusty, clean it witha mild soap or plain water and asoft cloth. Do not use solvents orstrong detergents.

Battery maintenance varies withthe type used. Basic maintenanceincludes visually checking the elec-trolyte levels and regularly verifyingthe specific gravity of your batteries

with a hydrometer. Add distilledwater as necessary, and clean andtighten battery posts (only the latterare required for maintenance-freebatteries). Also, check for any leaksor physical damage to batteries.Follow battery and charge regulatorinstructions for annual equalizationcharges that help cure the batteriesfrom plate fouling due to corrosion.

Generator maintenance for hybridsystems is simpler and easier thanusing a generator to produce allyour power. Change the oil as

recommended (which will be lessfrequently than for a continuouslyoperating generator).

Keep track of any maintenance or

modification made to the system(date and action). This will helpyou remember when your lastmaintenance routine was carriedout and may ease troubleshootingshould a problem occur.


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To further investigate which kindof system will meet your powerneeds, this section will help you

estimate your energy require-ments and then estimate thesystem size that your applicationwill require (a blank worksheet isprovided in Appendix A, page 40).Two examples have also beenworked out in the next section.Once you have followed thisprocess, you should be morecomfortable discussing differentoptions with a dealer.

If you are involved in the designof power systems, a more detailedsizing and design guide calledPhotovoltaic Systems Design Manual

is available from Natural ResourcesCanada (see Learn More AboutSolar Energy on page 46).

Step 1. EstimateYour Power andEnergy NeedsTo work out how much power andenergy you need, you must knowwhat loads you want to power,how much power they use (includ-ing stand-by consumption) andhow often they are used. For sin-gle-purpose applications, such aspowering a water pump, this isfairly simple to calculate. However,if you want a system that will runseveral appliances in your homeor business, you must estimate theusage pattern of each load.

The more energy you need, thelarger and more expensive thesystem especially if you wantan autonomous one. Therefore,decrease your energy require-ments as much as possible. This

includes using energy-efficientappliances and using electricityonly for appliances that really

require it. For example, it is notpractical to use a PV system topower an electric range or heatingsystem. Rather, meet your heatingand cooking needs with a morefitting energy source, such aswood or propane. A solar waterheater may also meet your hotwater needs (contact NaturalResources Canada for Solar WaterHeating Systems: A Buyers Guide2).

To estimate your power needs,first list all the loads you wantto power, note whether they are

AC or DC, and obtain their ratedwattage and the number of hoursper day they will be used (seeStep 1 of the worksheet inAppendix A).

If available, use the ratingindicated on the label of theappliance or tool you need topower. Also use the typical valuesgiven in Appendices B (page 42)and C (page 43) for common

appliances and lighting.Next, for each load, multiplythe power rating (using actualor typical values) by the numberof hours of estimated daily usageto obtain the total watt-hoursof power needed per day. If con-sumption is already given inwatt-hours per day (or kilowatt-hours per year, as on EnerGuidelabels), you can skip columns Aand B in Step 1 of the worksheet

and simply fill in column C usingthe watt-hours per day.

About Efficient Lighting

For lighting, consider ACor DC compact fluorescentlights instead of incandescentbulbs. They give four timesmore light per watt of elec-tricity and last 10 timeslonger. Consult a specializedsupplier for information onhigh-efficiency lighting for

outdoor applications.

24

6. EstimatingYour Needs

60W15W 10 1000h = 10 000h

Fluorescent lights use one quarter the energy of incandescent bulbs and last 10times longer.

2For your copy of Solar Water Heating Systems: A Buyers Guide, call Natural Resources Canada at 1 800 387-2000 toll-free, or visit the Web siteat http://www.canren.gc.ca.


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EnerGuide LabelsIf there is an EnerGuide label onyour appliance, you can use the

electrical consumption rating (inkilowatt-hours per year) given onthe label for your worksheet. Notethat the EnerGuide ratings forclothes washers and dishwashersinclude the electricity consumedin heating the water used in thoseappliances. These ratings are lessuseful to you if, as we recom-mend, you heat your water withsolar water heaters, propane orwood (instead of PV-generated

electricity).

If you use the value on anEnerGuide label, convert the kilo-watt-hours per year (kWh/a) into

watt-hours per day (Wh/d) forinclusion in column C of theworksheet in Appendix A. Tomake this conversion, multiplyby 1000 and then divide by 365.

Finally, fill in the subtotal(s),calculate the adjusted AC loads(for inverter losses) using 0.90 asyour initial conversion efficiency,and fill in the total daily loadvalue at the bottom of the first

side of the worksheet.Smaller, efficient applianceswill require less PV equipment.Some PV dealers also carryhigh-efficiency appliancesand lighting.

Always keep in mind that yourenergy requirement has a directimpact on the following:

the area of PV modulesneeded to power the loador recharge the batteries;

the capacity of the batteriesrequired to meet your needswithout running a generatorat night or on cloudy days;and

the amount of fuel used bya generator or the size of awind generator.

Watch Out ForPhantom Loads!

A growing number of elec-tronic appliances draw powereven when they are turnedoff. Examples are a TV orVCR that maintains programmemory, runs its clock andkeeps the remote-controlreceiver active. The stand-by

power required can appear tobe negligible, and it is oftennot even mentioned in appli-ance owners manuals. But itmay represent a substantialamount of energy becausepower is drawn 24 hours aday. For example, the stand-bypower for a remote-controlledportable TV may be as low as5 W, but it will still require120 Wh/d (5 W x 24 h). Thisrepresents the same amountof energy as using this TV(60 W) for two hours a day(120 Wh/d)!

25

EnerGuide labels provide energy consumptionratings (in kilowatt-hours per year) for majorhome appliances.


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For example, using a 1650-W hairdryer for eight minutes draws thesame amount of energy as usingfive efficient lights (11 W each)for four hours: about the amountthat one 50-W PV module pro-duces in an average day.

Hair dryer:1650 W x 8/60 = 220 Wh

Fluorescent lights:5 x 11 W x 4 = 220 Wh

Step 2. Make aRough Evaluation

of PV System Size2.1 Evaluate Which

Stand-Alone SystemIs More Suitable:Autonomous orHybrid

Stand-alone PV systems can beeither autonomous (with or with-out storage batteries), relying onlyon solar energy, or hybrid. Hybridsystems combine PV with one or

more other electrical generatingsources and normally includestorage batteries. Factors thatinfluence the type of systeminclude the following: total andpeak power requirements; whenpower is needed; required powerreliability; whether the applica-tion is seasonal or year-round;and whether the system will beeasily accessible or installed ina remote location.

Autonomous Systems

As the name suggests, autonomoussystems are self-sufficient and notbacked up by another generatingsource. They normally includebattery storage. Some applica-tions, such as irrigation, pumpingor greenhouse ventilation, requirepower only when the sun is shin-ing. Therefore, an autonomoussystem without storage would besuitable in such cases. In mostcases, however, power is neededwhether the sun is shining ornot, so the system includesbattery storage.

26

Power or Energy?The following two terms are used to characterize electricity usage:

the power or instantaneous power required; and the energy or energy consumption over a period of time.

Power

The power you need (the wattage) is the instantaneous intensity ofelectricity that is required to power the appliances you use. Themore appliances used at the same time, the more power required.Power is expressed in watts (W). A watt is a convenient SI unit inelectricity because it is simply the product of the current inamperes (A) and the voltage in volts (V).

1 W = 1 A 1 V

This simple formula indicates, for example, that a 12-W compactfluorescent light will require 1 A when connected to a 12-VDC (voltdirect current) power source.

Energy

Energy depends not only on the power required by your appliances,but also on how long and how often you use them. Energy isexpressed in watt-hours (Wh) for a given period of time (per day,month or year). It is defined as the power times the number ofhours the equipment is used over this time.

1 Wh = 1 W 1 h

The autonomous PV system in Yoho National Park, British Columbia, supplieselectricity for the amphitheatre projector and recharges the batteries of a golf cartthat the staff uses to collect camping fees. Photo courtesy of Sovran Energy Inc.


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In Canada, about twice as muchsunlight is available in summerthan in winter. To guarantee

power year-round using a solar-only system, a significantly larger(and hence more costly) array andbattery system is needed. Suchsystems are practical for applica-tions in remote, unattended sites,which are difficult and expensiveto visit, and where the capitalcosts are rapidly offset by avoid-ing costs for maintenance andfuelling visits. Thus, solar-onlysystems with storage are used for

electric fencing in remote areas,and in communications, markingand warning signs, monitoringsites and other situations wherereliability and low maintenanceare critical.

Autonomous systems are alsoappropriate for summer vacationproperties, sailboats and otherapplications where the period ofuse corresponds to the period of

greatest available sunlight. If youconsider power a luxury insteadof a necessity and can tolerate theodd occasion when the systemcannot meet your loads, anautonomous system may besuitable at a reasonable price.However, if you want guaranteedpower on a year-round basis andcan easily access the site, somesort of hybrid system will likelybe more affordable.

27

2.2 2.2

CANADA

600KILOMETRES

400200200 0

2.8

2.8

3.3

3.3

3.3

3.9

3.9

4.4

4.4

4.4 4.4 4.4

4.4 4.4

5.0

5.0

5.6

5.6

2.2

CANADA

600KILOMETRES

400200200 0

2.8

1.7

0.6

POLA

RNIGHT

2.8

1.1

2.2

2.8 2.2

0.6

1.1

1.7

2.2

2.8

1.7

1.7

POLA

RNI

GHT

Average daily number of peak sunlight hours in September (use for seasonalsummer autonomous systems). Source: Environment Canada.

Average daily number of peak sunlight hours in December (use for year-round-operated autonomous systems). Source: Environment Canada.


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Hybrid Systems

Hybrid systems use a combinationof PV and other power sources.Usually, hybrid systems use awind generator with a diesel,propane or gasoline generator asbackup. Hybrid systems may besuited for applications such asresidences and commercial build-ings that are not connected tothe grid. If you need more than2.5 kWh of energy per dayyear-round and already havea generator, or if you live in an

area that has poor sunlight forlong periods, a hybrid system isprobably a good choice.

Hybrid systems generally includebattery storage; the load drawspower from the batteries. Whenthere is enough sunshine, the PVarray keeps the batteries charged.If a wind generator is incorpo-rated, it charges the batteriesduring windy periods, which areoften when it is overcast or at

night. For this reason, wind andsolar equipment are a perfectcomplement to one another.The diesel or gasoline generatoris needed only once in a whileto charge the batteries duringextended overcast and calm

periods. The generator operatesat nearly full capacity, and thisresults in a better generator duty

cycle, more efficient fuel use,lower maintenance costs andlonger generator life. Applicationsthat involve both solar and windequipment often do not needa gas or diesel generator.

2.2 Estimate theAvailable Sunlight

Knowing the solar resourcesavailable is key to the designof an efficient and affordable

PV system. The maps on page 27show the average daily valuesof peak sunlight hours that strikesouth-facing, fixed PV arraysin various parts of Canada inSeptember and December.These values assume that thearrays are tilted at right anglesto the sun at noon. Alternatively,you can get weather and solarradiation values for selected sitesfrom Environment Canadas

Meteorological Service of Canadaor from RETScreen Internationalsoftware (see Learn More AboutSolar Energy on page 46).Choose a value for your locationfrom either the September or

December map, and insert thisvalue under Step 2 of the work-sheet in Appendix A.

In the summer, September hasthe fewest hours of peak sunlight.Overall, December has the fewesthours of peak sunlight. To esti-mate the available sunlight designvalue for a seasonal (summer)autonomous system, use thevalues from the September map.To estimate the available sunlightdesign value for a year-roundautonomous system, use the

values from the December map.For a PV-diesel hybrid system,you may choose Decembervalues or average the two values(September and December). Thisis described in the case studyon pages 33 and 34.

28

Parks Canadas remote camp locatedin the far north on Ellesmere Island,Nunavut, is powered by a PV array

(on a tracker) combined with a windgenerator and a gasoline generator.


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2.3 Estimatethe RequiredPV Array Size

The next step is to size the PVarray. This takes into account

power losses in battery charging(Effbat of 75 to 90 percent) andregulator efficiency (Effreg of 80to 90 percent), especially if thecontroller does not include a

maximum power point tracker(MPPT) (see the glossary on page44). Typically, an MPPT is usedonly for medium to large systemswhen benefits related to energy

gains are greater than the cost ofthis feature. Additional losses dueto dust or snow accumulation onmodules are likely, but they arerelatively low.

After you determine the arraysize (in watts), estimate the num-ber of modules required. To dothis, divide the array size by thepower rating of the module you

intend to use in your installation(normally 20 W to 100 W).

29

Technical Note: Definition of Units Used to Describe a PV System andSome Orders of Magnitude

Full (peak) sunlight: 1000 W/m2 of energy density (about the intensity of the sun at noon on a brightsunny day)

1 hour of peak sunlight: 1000 Wh/m2, the equivalent of 1000 W/m2 during one hour (e.g. 2 h at 500 W/m2 or1 h at 600 W/m2 and 2 h at 200 W/m2)

100-W PV module: Power capacity of a PV module able to produce 100 W of electricity when maintainedat 25C and exposed to full peak sunlight (1000 W/m2)

100 W (PV) exposed to 1 h of peak sunlight = 100 Wh of electricity

Rule of thumb: Typical annual radiation in Canada is 1500 h of peak sunlight (range of 11001700 h).

100 W installed = potential of 150 kWh/a.

Due to system losses and other causes of inefficiency, the energy production ofPV systems is often estimated as follows:

100 W installed 100 kWh/a

Power, Voltage and Current Ratings of Typical PV Modules

Module Rated Power (W) Nominal Voltage (V) Nominal Current (A)

Kyocera KC 120 120 16.9 7.1

Siemens SM100 100 17.0/34.0 5.9/2.95

Solarex SX-85 85 17.1 4.97

BP Solar BP-275 75 17 4.45

CANROM-65 65 16.5 4.2

Photowatt PWX500 50 17 2.8

UNI-SOLAR US-21 21 21 1.27

Note: The above modules are examples of those available on the market. Each manufacturer provides a complete line of modulesthat have different sizes and power ratings. This list is not an endorsement of these products.


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2.4 Estimate BatteryCapacity forAutonomous Systems

The size of battery you needdepends on whether you requireuninterrupted power and howmuch you are prepared to payfor that privilege. For a weekendcabin or cottage, you may notreally mind if the power failsoccasionally during an extendedovercast period. On the otherhand, uninterrupted powermay be a necessity for someapplications.

For most applications, a good ruleof thumb is to provide enoughbattery storage to supply power

during three to five overcastdays. (Battery capacity for hybridsystems is usually enough for

only one or two days). A batteryshould not be completely dis-charged, so as not to shorten itslife. Thus the available capacityof a battery is less than the name-plate rating. A maximum depthof discharge factor is alreadyincluded in the equation in theworksheet (see Step 2 in AppendixA on page 41). It ensures thatthe battery charge never dropsbelow 50 percent of full charge.

This value depends on the typeof battery you select. Consultyour dealer.

Use the blank worksheet to helpsize your stand-alone PV system.Now that you have estimated

the size of the PV array and theamount of battery storage yourequire, you are in a position toapproach a dealer. Discuss costsand make decisions on what isbest for your particular situation.

30

Technical Note: Battery Capacity Rating

Watts may be expressed in Wh (volts x amps). Likewise, energy may beexpressed in Ah (amperes x hours) at a given voltage. This is often usedin the battery industry to express battery capacity. For example, a batterywith 960 Wh of capacity is generally referred to as a 12-V, 80-Ah battery(12V x 80 Ah = 960 Wh).

Wh = V Ah


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In the following examples, two hypothetical casestudies show how the worksheets can be used. TheSmiths, for example, are interested in PV power for a

remote vacation cabin. The Wongs, meanwhile, wanta system that will provide reliable power year-roundfor their home and business. Both families are inter-ested in renewable energy and want to know if a PVsystem would be appropriate for them.

Example 1. Summer CabinPower System The SmithsThe Smiths own a small vacation cabin where they

spend most summer weekends and holidays, as well

as the occasional weekend in the winter. The cabin has

no electricity or running water and is far from the grid.After several years of filling oil lamps and hauling water,

the Smiths would like to enjoy the benefits of electricity.

However, the cabin is their escape from the noise and

pollution of the city, and they would prefer a quiet,

non-polluting power source. They are particularly

interested in a PV system because it is durable and

requires low maintenance.

The Smiths main priority is to keep costs at a mini-

mum, and they are willing to sacrifice power availability

to do this. After all, they do not have power now, and

the thought of the odd blackout does not bother them.

They have a propane-powered refrigerator, and they

are willing to switch to fluorescent lighting and make

do with a minimum of appliances to keep their power

needs low. For their needs, a system that is small, solar-

only and is stand-alone appears to be a good solution.

Working through the worksheet, the Smiths find that

roughly a 120-W (watt) system and about 211 Ah(ampere-hours) of batteries could meet their needs

at a price they can afford.

31

7. Sizing Worksheet Examples

Worksheet: The Smiths (Summer Cabin)

Step 1. Estimate Your Power and Energy Needs (watt-hours per day)

AC or DC (A) Rated Wattage (B) Hours (C) Watt-Hours Per Day(check one) (actual or Used (A) x (B)

Appliance Load AC DC typical values) Per Day AC DC

Kitchen lights (2) (12 V) 15 1 h (x 2) = 2 30

Bedroom lights (2) (12 V) 15 1 h (x 2) = 2 30

Living-room lights (2) (12 V) 15 4 h (x 2) = 8 120

Water pump (12 V) 90 1 h 90

Stereo (12 V) 6 4 h 24

TV (black and white) (12 V) 20 3 h 60

Subtotal: AC: N/A Wh/d DC: 354 Wh/d

Adjust AC loads for inverter losses: AC load = 0 Wh/d: 0Effdc ac 0.90

Total daily load: DC loads + adjusted AC loads = 354 Wh/d

DC to AC inverter efficiency (Effdc ac) ranges from 80 to 95 percent (0.80 to 0.95). To help you with your first

calculation, 0.90 has been inserted in italics. Adjust the efficiency figure, if necessary, once you have chosen theinverter for your system and have read the manufacturers ratings.

The Smiths do not need an inverter because all their loads are 12 VDC (volt direct current). They can add one atany time.


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32

Worksheet: The Smiths (Summer Cabin)

Step 2. Make a Rough Evaluation of PV-System Size

2.1. Evaluate Which Stand-Alone System Is More Suitable: Autonomous or Hybrid

This summer cottage will be equipped with an autonomous PV system.

2.2. Estimate the Available Sunlight

Sunlight: 3.9 h/d (Consult maps on page 27 or

see Learn More About Solar Energy on page 46.)

2.3. Estimate the Required PV Array Size (W)

Array size (W) = Total daily load (Wh/d)

Peak sunlight hours x 0.77*

= 354 Wh/d

3.9 h/d x 0.77

= 118 W**

* The factor 0.77 assumes a 90-percent battery chargeregulator efficiency and an 85-percent battery efficiency.

** Based on rated power output of PV modules if an MPPTcontroller is used (see the glossary on page 44). If an MPPTcontroller is not used, further losses should be accountedfor, resulting in an increased power capacity of1525 percent. Consult your dealer.

2.4. Estimate the Required Battery Capacity

(ampere-hours)

Nominal voltage of battery: (V bat): 12 VDC

(typically 12, 24 or 48 volts)

Number of days of battery

storage needed (a good rule of

thumb is three days for an

autonomous system): 3 d

Battery capacity (Ah):

Total daily load (Wh/d) x days of storage

Battery voltage (Vbat) x 0.42***

= 354 Wh/d x 3 d

12 V x 0.42

= 211 Ah at 12 V

*** The factor 0.42 assumes an 85-percent battery efficiencyand a 50-percent maximum depth of discharge. If thebattery is used at temperatures lower than 25C, itscapacity (ampere-hours) will decrease. Consult yourPV system supplier.

Autonomous

seasonal use (summer mainly)

year-round operation withlow energy requirements (< 1 kWh/d)orlow requirements for power availability

limited/expensive access to the site

maintenance is an issue

Hybrid

year-round operation andenergy requirements > 2.5 kWh/dorhigher latitudes

already have a generator

very high requirements for power availability


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Example 2. Year-RoundRemote ResidentialPower System The WongsThe Wongs are a young couple who have been living

beside a small lake for several years, away from the

electric grid. They run a small handicrafts business,

manufacturing woven goods. The Wongs use a

propane generator to provide power for their home

and studio. But they have grown tired of constant noise

and pollution, increasingly high fuel bills and frequent

maintenance requirements. Their electrical consump-

tion is low despite many loads because the fridge and

stove run on propane. (Running large loads on propane

greatly reduces the up-front cost of a PV system.)

After filling out the worksheet, the Wongs find thatmeeting their needs with an autonomous system would

be too expensive. They figure that they can currently

afford only a small fraction of the PV panels required,

but they may be able to add more panels in a few

years. In the meantime, they decide to combine their

existing propane generator with PV panels to make a

hybrid PV system that offers the potential to reduce

the aggravation and costs linked with using a genera-

tor. Based on their current resources, this appears to

be their best option. Knowing this, they are now in a

better position to talk to a PV dealer about the type

of system they want.

Worksheet: The Wongs (Year-Round Residence)

Step 1. Estimate Your Power and Energy Needs (watt-hours per day)

AC or DC (A) Rated Wattage (B) Hours (C) Watt-Hours Per Day(check one) (actual or Used (A) x (B)

Appliance Load AC DC typical values) Per Day AC DC

Fluorescent:

Kitchen lights (2) 15 3h x 2 lights 90

Living-room lights (2) 15 5 (x 2) 150

Bedroom lights (2) 11 2 (x 2) 44

Basement, bathroomand hall lights (4) 15 1 (x 4) 60

Freezer (very efficient) 600

Water pump (12 V) 90 2 180

Outdoor lights (2) 15 8 (x 2) 240

Clothes washer (front load) 160 1 (1 load) 160

Furnace fan 250 4 1000

Workshop lights (4) 15 7 (x 4) 420

Radio (in workshop) 5 7 35

Colour TV (no remote control) (12 V) 60 3 180

Vacuum cleaner 800 0.25 200

Intermittent loads 1000 (estimate) 1 1000(e.g. coffee-maker, iron, smallpower tools, block heater, etc.)

Subtotal: AC: 3999 Wh/d DC: 360 Wh/d

DC to

Documents

7524357 Consumer Photo Voltaic Systems a Buyers Guide