But while their Voc is 21-23, the voltage under load is only 13.5-18.I'm thinking that if I get a bottom-of-the-barrel panel at only 13.5 volts that they won't be able to charge a 12V battery bank. So my plan is to string them together to create 27-36 volts and then use a 24->12V MPPT charge controller to charge the 12v batteries. Is this a good idea, or can I save some money and safely stick purely with 12V?
I narrowed it down to the Morningstar Sunsaver (15A) and the Blue Sky SOLAR BOOST 3024i (30A). I'm leaning more heavily towards the Morningstar since it's cheaper and can handle 240 watts (24V * 10A) with 50% overcurrent capacity.
