How to Calculate Your Kit Size in Detail
If you run 2 40 watt light bulbs and a 10 watt radio for 3 hours per day you need to have 270 watt hours of power.
2 x 40 = 80 watts (W)
80W + 10W = 90W
90W x 3hours = 270 watt hours (Wh)
The $769 solar system has one 75 watt (17.2V/4.35A) solar panel which means that the panel produces 75 watts of maximum power in full sunlight.
Effectively it charges the batteries with 4.35 amps.
During a normal southern California day we have about 6 hours of full power.
4.35 amps x 6 hours = 26.1 amp hours (Ah)
Multiply 26Ah times the battery voltage 12 volts (V)
26Ah x 12V = 312 watt hours (Wh)
This is your daily available net DC electricity.
In order to use this power with your normal AC appliances
you must invert 12VDC into 120VAC.
This decreases your efficiency to about 90%.
312Wh x 0.9 = 280 Wh net AC electricity per day.
Which means you can run a 280 watt load for 1 hour or a 28 watt load for 10 hours or 2 40 watt light bulbs and a 10 watt radio for about 3 hours.
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