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How To Size a Power-Generation System
By now, you will probably have decided to use either solar cells or
a windmill to generate electricity. The next question is, how big
should the windmill or array of solar panels be? You know how much
electricity you need from your inventory; now you need to make sure
the system you buy will actually generate that much electricity.
Otherwise, you may not be able to run that air conditioner!
By the way, don't forget to write down the information as you find
it: you will need it when you write your uncle a letter explaining
why he should buy the system you suggest!
Click on the type of system you chose: solar wind
Solar
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Different locations receive different amounts of sunshine. Therefore, maps have
been developed to indicate how many useful hours of sunshine, on average, a given location receives.
You need to consult a solar radiation map to determine how much sun shines on your uncle's ranch. Click on the link
below to find a map that will provide this information.
Solar Resource Map
Use the map to determine the average number of sun hours per day that can be expected on your uncle's ranch.
Refer to the calculations section of your Electrical Inventory Form. In the Solar table, record the expected sun hours on Line 1.
A solar panel is rated according to the number of watts it will produce in one hour of direct sun.
When you performed your energy inventory, you
decided the total daily energy, in Watt-hrs, that you need. Divide this total by the number of sun hours you determined your
uncle's ranch will receive. This tells you the minimum
watts you will require from solar panels. Record this information on Line 2 of the Solar table.
After you know how many watts your solar panels need to generate, go to
http://www.mrsolar.com/page/MSOS/CTGY/remote. Several off-grid kits are described on the page. After you read what is included in each kit,
choose the smallest
system that will provide the electricity you need. (For example,
if you need 200 Watts, choose the 340 W kit, not the 170 W kit.) If you need more power than the biggest kit will generate, add extra solar panels. (On the menu click Products > Solar Panels > By Wattage.)
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It's time to write a
proposal!
Wind
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We will assume your uncle is going to buy one or more 1 kW systems from Bergey.com.
In order to determine the number of wind turbines required, you need to know (a) how much wind your uncle's ranch receives and (b) how much energy
the turbine produces for that amount of wind.
Maps have been developed to indicate the average amount of wind
a given location received. Follow the link below
and use the map to determine the average wind speed in Starr
County, TX. Then use the table below the map to determine the daily energy production, in kWH, of Bergey.com's XL.1 turbine.
Wind Energy Information.
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Refer to the calculations section of your Electrical Inventory Form. In the Wind table, write the Wind Class down on Line 1.
Also, write the predicted energy production on line 3 of the Wind table. To fill in Line 2, take the total daily energy need you calculated and divide by 1000.
This will give you the energy in kW-hrs. Divide the total kilowatt-hours by the turbine's energy production to determine how many turbines you need.
A wind-turbine is only part of the investment. In order to power a house, you must also purchase a tower, batteries, wiring, and other components. A 1-kW turbine costs $5,000, but it will take about $12,000 to install it properly.
Use the installed price when you calculate how much your uncle will need to spend on a wind system.
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It's time to write a
proposal!
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