That problem was solved 20+ years ago. Typically you have an element halfway up the tank, so the electric heats the top half only, but the solar heats the full tank.
Ripple, timer, or remote control can shift electrical consumption to times of lower cost (overnight, mid-afternoon) while having negligible impact on quality. A big tank will stay hot for a few days easily.
I had one in a rental I lived at for a while until it broke, that one used an instant gas boiler behind the tank to heat up the water more. The system you describe would be better (but by smart, I meant it should also take into account when free solar power is available, and predict when we’re going to use hot water).
It depends on the utility pricing as to what’s best in that regard, but yes, solar diverters on conventional electric-only tanks are pretty common in NZ. It’s pretty rare to put both PV and solar hot water on the same house.
That problem was solved 20+ years ago. Typically you have an element halfway up the tank, so the electric heats the top half only, but the solar heats the full tank.
Ripple, timer, or remote control can shift electrical consumption to times of lower cost (overnight, mid-afternoon) while having negligible impact on quality. A big tank will stay hot for a few days easily.
I had one in a rental I lived at for a while until it broke, that one used an instant gas boiler behind the tank to heat up the water more. The system you describe would be better (but by smart, I meant it should also take into account when free solar power is available, and predict when we’re going to use hot water).
It depends on the utility pricing as to what’s best in that regard, but yes, solar diverters on conventional electric-only tanks are pretty common in NZ. It’s pretty rare to put both PV and solar hot water on the same house.