Re: The trick is *useful* energy
Scale this down to house-sized? Sounds as if you could have 2-3kWp of electricity, and store the hot water in a tank (somewhat larger than the standard one with immersion heater). Can you say free hot baths for the whole family almost anytime they want?
Yes, you might have to dump some surplus hot water at the height of summer, but so what? You still have the electricity. I suspect it's possible to dump the heat into the earth through a ground source heat pump running backwards in summer, and reclaim much of the heat in winter, but that would be another story. Or use a large (underground, well-insulated) tank of water instead of ground?
The main question is whether this sort of solar PV panel can be cheap enough compared to the ordinary sort, once the supply of free hot water is factored in.