Water is heated in a tube that's surrounded by a larger, vacuum-sealed glass tube. Very little heat is lost because there's no air between the heating liquid and the outside world. Solar water ...

Cut the tube and fit it to the pump outlet ... if you create a shallow bowl and add a pump like this AUTGA Floating Solar Powered Water Fountain Pump, you could make a water fountain suitable ...

Similarly, absorbent plates on a roof can heat liquid in tubes that supply a house with hot water. Solar energy is lauded as an inexhaustible fuel source that is pollution- and often noise-free.