dewey02 wrote:
So can the Grape Solar 40 Amp PWM controller really handle those to 120 watt panels in series and still output to charge a 12 volt system battery? I didn't think it could, but you've said yes. If it can, then I would definitely want to wire in series. Thanks.
You do not want to wire 12V panels in series to connect to a PWM controller, even if the controller can handle it. Panels in series increase the voltage, but not the amperage. And charging always occurs at battery voltage, so series wired panels would just have their voltage pulled down to the battery's level, with little increase in current over a single panel. So there would be no advantage to doing so, in fact it would basically make the 2nd panel useless. Wire them in parallel - the panels will put out more current to the battery, guaranteed, and that's all that matters. Voltage drop in the wires is directly related to the amount of current. Trying to reduce it by raising the voltage into a PWM controller is just plain :S. Reductio ad absurdum, you can reduce the voltage drop to zero by not hooking up any panels.
