a solar collector
Black materials solar collector absorb solar radiation very well, and when they heat the water round them. that is a very easy design, however the flat panel can become very complicated. soaking up plates can be used if high temperatures are not required, but gadgets that generally use reflective materials to cognizance sunlight result in higher solar collector temperature programs.
https://www.aspessolarproducts.com/solar-collector
solar heater for house
https://www.aspessolarproducts.com/solar-water-heater/heater.html
solar thermal colector power
https://www.aspessolarproducts.com/solar-water-heater/thermal-colectors.html
