Originally Posted By: tanstaafl.
Originally Posted By: K447
or even better, heat the water with a rooftop solar water heating system.
Like this. It provides water hot enough that I have to be careful, and in sufficient quantity to serve two apartments.

Interestingly, even on a hot day when many things are uncomfortable to touch, those glass tubes transfer heat so effectively that they feel cold.

tanstaafl.

Precisely like that.

Those vacuum insulated tubes can provide hot water even in cold Canadian climate and on moderately overcast days.

If there was a cost effective way to convert excess thermal hot water into electricity, PV and batteries would not be needed.