Solar water heating.

This isn't meant to be insulting, we are learning too, having just installed solar panels for electricity production.

Solar. Needs sun to work. Not heat, not temperature, but actual solar so it can produce. We were installed Nov 30, and watch it on line pretty much constantly. We are still intrigured. It can be HOT, but unless the panels actually have the sun beating down on them, they don't produce much.

Probably the same with your intallation. Batteries? Storage devices? Not often used here, we do usually have LOADS of sunlight, and it keeps the cost down really low. The cost for our panels which produce 50% more than we use was ridiculously low.