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Unread 08-07-2009, 11:03
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Re: Solar Battery Plant Question

Ok....hmmmm...

Keep in mind that solar panel power ratings are a bit funny, they are rated at some voltage and at some current, but the voltage is at no load, and the current is into a short circuit, so you do NOT get the max rated voltage and current at the same time! A 75w panel might put out only 5 amps when charging at 12v in full sun.

Think carefully about how long you will want to run the device, and how long you can have it charging. Usually it's more cost effective to buy more batteries and leave it charging as long as possible, than to buy more solar panels.

You probably want a charge controller that is rated for a bit more current than your panels can generate.