Pretty much all houses in Greece have this and no, it is only good for the summer or sunny days. But still it is a no brainer, unlimited free hot water during the summer and limited free hot water during most days.
The tricky part is calculating whether it was sunny enough(during the winter) to produce enough hot water for your shower or if you need to turn on the electric water heater.
Some greeks pre-emptively turn on the electric heater for 15-30 mins, other more financially stressed greeks prefer to gamble.
Just because Israel is using this for propaganda, doesnt mean that it isnt true(or important). The USSR used american racism against black people for propaganda but that doesnt mean that there was no racism in the US or that racism wasnt important(or relevant to the discussion between 2 global powers).
When someone tells you “gay people should be killed”, i think it is relevant to the discussion you have about that person.