In the 1800 people started experimenting with the suns solar power by a metal water tank, painted black, into the sun to absorb as much solar energy as possible. These were the first solar water heaters on record. The downside was that even on clear, hot days it usually took from morning to early afternoon for the water to get hot. And as soon as the sun went down, the tanks rapidly lost their heat because they had no protection from the cool night air.
The shortcomings of theses bare tank solar water heaters came to the attention of Clarence Kemp, who sold, in Baltimore, Maryland, the latest home heating equipment. In 1891, Kemp patented a way to combine the old practice of exposing metal tanks to the sun with the scientific principle of the hot box, thereby increasing the tanks' capability to collect and retain solar heat. He called his new solar water heater the Climax - the world's first commercial solar water heater. Kemp originally marketed his invention to Eastern gentlemen whose wives had gone off with their maids for summer at some resort, leaving their husbands to fend for themselves. The solar water heater, Kemp advertised, would simplify housekeeping duties for this class of men already burdened by their wives and domestic staff’s absence and unaccustomed to such work as lighting the gas furnace or stove to heat water.
Modern day solar evacuated tubes use the latest magnetron sputtering deposition techniques, and layers of aluminum-nitrogen and aluminum base. This produces tubes that can harness nearly 92% of the suns energy.This new technology has caused the world to look at the renewable source from a different light. Currently there are over 1.5 million solar water heaters in the USA over 1/3 of the Asian population use solar water heaters, and this number is rapidly climbing.