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The size and quantity of solar panels and batties really depends on what appliances you want to run. Here is an example of how to size a solar panel system.
* 19" Color TV (70W) 7 hours 490WH
* VCR (40W) 4 hours 160WH
* Furnace (400W) 3 hours 1200WH
* Satellite Dish (40W) 7 hours 280WH
* 2 Compact Lights (16W each) 14 hours 448WH
* Tape Player (30W) 7 hours 210WH
* Laptop (40W) 7 hours 280WH
* Coffee Maker (900W) 28 min 420WH
Total Watt Hours used 3488 in a week or about 500 in a day.
With about 5 hours of sun a day you can generate 3500W Hours in 1 week with a 100 Watt panel. (5h of sun/day x 100W panel = 500WH a day)
We need a battery that stores at least 500W hours (to store a days worth of electricity), however it is better to size the battery for more than just 1 days use in case you have a cloudy day or less than 5 hours of sun a day.
Find the specs on the batteries you want to use, you will need to know the discharge rate.
For this example I chose the GPL-31T which at 12V and 25A discharges in 195 minutes.
To calculate Watt Hours:
12V x 25A= 300W
195min / 60min per hour = 3.25Hours
300W x 3.25H = 975WH
This battery will supply almost 2 days worth charge from the solar panels.
If you want to run more appliances or for longer periods of time then you can adjust the above calculations and increase the number of panels and batteries.
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