Wednesday, Mar 18, 2009 at 08:18
A solar panel is different to just about every source of DC around us - it's a constant-current source.
A car battery is a constant voltage source - whether I connect a tiny LED or a 100 watt bulb to it, it will put out 12 volts.
A 120 watt panel in sunlight will put out about 7 amps - whether you connect it to an 18 volt battery, a 12 volt battery, a 6 volt battery or a short-circuit.
A standard way to
test a panel is to connect it directly to a multimeter set to 10 amps - the multimeter is effectively a short-circuit. DON'T try this with any other DC source you have !!!
The only reason for having a regulator is to stop charging the battery and damaging it when the battery is full.
If you have the multimeter set DC volts 200, you should see more than 20 volts in sunlight.
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