Natcore Technology scientists have created a black silicon solar cell with an average reflectance of 0.3%, making it the “blackest” solar cell ever designed. Compared to the most efficient solar cells currently on the market, Natcore’s development offers a tenfold decrease in reflectance over the solar spectrum. The result is an increase in energy efficiency that could help solar power compete even more effectively with traditional fossil fuels.
"This option is small-scale and it is built around a reclaimed heat dispersal system from an old refrigerator (which you can get with the gas removed from your local dump). It has no pump as it is gravity fed and it requires no electricity to work. Just put it in the sun, turn on the water feed and you will get a slow but constant supply of very hot water..."