I'm figuring a use of about 4.6kw/day if we wanted to boondock completely off-grid.
Given that usage I'd need about 383Ah at 12v or about a 400a system. If I went to using 2 of the 280ah in parallel for 580ah then I'd have some extra wiggle room and we could plan on pulling into an RV place every 3-4 days to charge overnight.
If I add another solar panel to give myself 1040watts solar (instead of 875watts) then the average sun of 3.83 hours in Maryland (and similar latitudes) would let me get pretty close to running everything off batteries. I'd probably have to shut things down to a minimum about every 3 days and use that to recharge the batteries. If we can figure out when those maximum sun hours are and cut off the loads that draw so much power (mostly computers/internet from my calculations) during those hours then we should be able to dump most of the power back into the batteries.
But it still leaves me figuring out how to do storage for about 4.6kw/day.
I'd do a 24v or 36v system but I think (not positive yet) that a 24v system at lower amps would take longer to charge the batteries. Still trying to work out calculating charge rate for given voltage/amps.
tony.latham wrote:I've been looking at doing a DIY powerwall for my solar storage either out of...
I assume this is for your camper. How many amps do you need?
Tony