Have a 20V 40W solar panel and it is attach to two backup batteries. Just want to know know how many watt of inverter do I need?
It depends on what you want to run from the panel. A 20W inverter might last a long time, but would not run much. A 00W inverter might run down your batteries in a few hours. It might help if you posted how much capacity (Volts, Amp-Hours) the batteries have.
