Not sure if it’s exactly what you’re talking about, but something similar is pretty common in China as well. I’ve heard people call the system “solar power“, bu

Not sure if it’s exactly what you’re talking about, but something similar is pretty common in China as well. I’ve heard people call the system “solar power“, but what they’re referring to is effectively a tank of water on the roof that is heated by the sun which is used as the hot water source for showers, etc.