I really like invention like this which is pretty useful and save cost. A Chinese farmer Ma Yanjun wanted his mother to shower with hot water so he invented a solar-powered water heater out of beer bottles. Ma put 66 beer bottles attached on a board and those bottles are connected to each other to let water flows through them. The sunlight will heats the water as it slowly passes through the bottle before flowing into the bathroom as hot water. Ma says that it provide enough hot water for all three members of his family to have a shower everyday.

[via Neatorama]