Solar charging maintaining help

champdog wrote:
Thanks for the replies. Im still green when it comes to solar but Im reading enough that its making me want to dive head first into being as solar efficient as possible. I have another question. In learning how mppt works it sounds like its way way better for actually recharging a battery bank. Do the mppt controllers work like a good 3 phase type float charger and if I have 12v panels on the roof in series with a mppt isnt that going to be way better than my roof panels wired parallel with a pwm controller? I have 2 group 31 agm batt's and would like to get as close as possible to never have to worry about charging with the genny or ruining my batt's. If a mppt would always be a better choice to try and achieve those goals Ill opt for the mppt. Are 24v panels a better choice than 12v if your using mppt? THANKS!!!!!!

For actual charging of the batteries, the best solar charger I've seen to date is the Bogart SC2030 coupled with a Trimetric 2030 to control it. By monitoring temp, and both voltage, and current flow right at the battery it can do some very controlled charging of your batteries, neither under or overcharging. The Bogart setup is PWM. Where MPPT controllers shine is in converting excess voltage into increased amperage. Unlike batteries and the like which are primarily fixed voltage variable current devices, solar panels are more fixed current variable voltage units. (Lost a lot in trying to simplify there) With high voltage panels, you'll be able to flow more current into your batts with a MPPT controller vs. PWM. Good solar controllers are adjustable 3 stage controllers, and at least in the case of the Bogart setup mentioned you have 4 stage charging options available.

As for parallel vs series. Myself for the most part I prefer parallel, unless you have bypass diodes in the panels and can keep the system to a single string. From what I've seen MPPT controllers don't do well with parallel wired panels if one panel drops out for shading etc so PWM tends to work better here. With parallel strings I think the best option is 1 mppt controller per string, with of course bypass diodes, or use a PWM controller for the parallel setup.