It was reported on chat sites that all new houses in Spain had to have solar panels for water heating etc as from 2008 (I think), however this appears to be antoher one of those rumour thingys as haven't seen new builds with them fitted as a matter of course. Another "however" is that the government is giving grants up to 35% to have them installed. Have absolutely no idea of how much these systems would cost or whether you would recoup your money but, as fuel prices are constantly on the rise, it might be worth looking into. This, however, is far from new technology. I remember one of our married quarter blocks in Cyprus being fitted with them back in 1982 as an experiment. The occupants were told to leave the hot water on all the time rather than putting it on a timer so that costs could be compared. ISTR the bills at the end of the quarter were about triple what they normally were but that was probably the way the Cypriot workers had wired them up. Don't know what the final outcome of that was.
And, although my house has had no adverse problems throughout the (what we shall have to learn to call it) the rainy season, some houses with open porches have had a lot of damage, especially to the front doors. When I had a quick look (nosey devil that I am) the damp courses (yep, they had been fitted) only comes up to the level of the porch so all the rain pouring in has caused damp on the internal walls above the damp course. Ah, well. I believe the owners of the houses are taking legal advice as the builders say it is not their problem. Mind you, the streets outside were totally awash with water in the last rains, so much so that one of our neighbours was a bit concerned and check the interior of a lot of the houses but, thankfully, no damage or leaks.
At least in Cyprus they were a bit more prepared and there are monsoon drains everywhere to take away the excess. Or there were until the building malaise took over there just as it did on the Costas. The older areas had the monsoon drains but the newer builds hadn't bothered. Most of the flats and houses in Cyprus used to have flat roofs so that didn't help. You will also see building iron and reinforcement frames sticking out the top as they could then be declared unfinished (in case the owner wanted to build on top when his daughter got married for a dowry) and a lower tax was paid on the building. Don't know if that's still the case as I haven't been there for over 20 years.