Yep, also, say, Israel, Tunisia, in practice most of south mediterranean countries, basically anywhere houses have terrace roofs. The tank is just a water boil

Yep, also, say, Israel, Tunisia, in practice most of south mediterranean countries, basically anywhere houses have terrace roofs. The tank is just a water boiler, to store the heated water and usually (not always) it has a resistance heater for those few cases/days when hot water from sun heating is not enough. The only issues with these is that they are suitable for single homes (or however small, self-standing,) as the water pipes have to go up to the roof and back, the commmon ones are pumpless[1] (so multi-stores/multi-apartments becomes a problem), though they do make much more complex systems (with pumps, mixers. etc.) for such buildings. Example (from a Greek manufacturer): https://www.andrianos.gr/en/products/solar-thermal/solar-water-heaters https://www.andrianos.gr/en/products/solar-thermal/solar-wat...