- Last Active
- Solar Expert
There are lots of variables to consider, but I'd probably continue on with the existing pump and if it dies, replace it with a similar one. It's < 100Wh/day and not a huge startup surge - don't spend much to optimize it.1
Running it during absorb makes the most sense to me, although it only needs ~.3kwh. Maybe build a foam box for it and fill it with cellulose to reduce cool down.1
3 hours of sun on 1 sq foot might yield ~450 btu. 5 gallons raised 40F (eg, 70F to 110F, well short of 140F) needs ~1700 btu (ie, not even close no matter what efficiency you pick). A 2'x2' panel would be better.
I don't know anything about the Kid or understand your battery wiring - maybe you could wire the load diversion output to a relay that would turn on the water heater (running from the batteries).1
But if nobody bought cobalt, then my guess is that these children would be put to work doing other, similarly bad labor. So not buying lithium/NiCd/NiMH batteries doesn't help this "must be solved" problem.
Maybe someday residential electricity will be priced on a minute-by-minute basis, with the price always being available via the Internet.1