The idea is to have a fully solar-powered hot tub...

A small 12V PV panel would be enough to run a circulation pump for filtering purposes ... though i think a UV filter might need 120 AC. OK, no big deal... could either run something down from the greenhouse, or do a small inverter right there at the tub. I have 12 3x8' thermal panels for heat. Excess heat could be shunted to the earth under the greenhouse, to keep it toasty all winter long.

The greenhouse would be above the tub, and the tub in-turn above the thermal collection panels, allowing for full thermo-siphoning... no pump required (or perhaps just a very small pump).

the proposed location for the tub

this is below the house, and a little bit of a hike...
so worth it on a crispy-cold winter night

there's a sweet outcrop of rock, from which upon one can gaze both up & down the canyon,
even out east to the Great Plains...

the view from the tub out to the plains... east

the thermal panels

these were freebies from a dismantelling project whereby the old --perhaps disfunctional-- thermal system was being replaced by a brand-spanking-new PV system (i know... doesn't make sense to me either) ...the price was too good to pass up!

it's uncertain how many of these i would actually need for the hot tub... probably about half of 'em, but those numbers are yet to be crunched