I wondered if I was oversizing things. The pump specs show a draw of 1.4 amps at 115v = 160 watts, so that was the basis for selecting that size panel. I assume that the pump should be running nearly all the time that the sun is shining and that therefore there will be pretty much a steady-state situation between the pump and panel, except for momentary cloud cover as you mentioned in your original post. The battery would seem to be acting as a very short term (a few minutes generally) buffer, not providing significant storage for any length of time.
That panel I selected seemed to be the cheapest at that output, and I figured that the MPPT charge controller could manage the 24-12 v business.
Re the whole solar thing- certainly power cost is not the motivation since its pretty minimal as you say. Rather its the doomer side of me that would like have this operate without needing grid power. In case of no power, I can run a generator just enough to get water from the pump to charge my fairly large pressure tank, and then I'd have hot water, sans electricity.
Thanks for your continued dialog. I've been doing some research, but there's nothing like talking this stuff through with someone.
Regards,
Greg
