1891: Baltimore Inventor Patents First Solar Water Heater

Inventor Clarence Kemp of Baltimore patents the first commercial solar water heater. Kemp, who sells cutting-edge home heating equipment, combines the older practice of exposing metal tanks to sunlight with the scientific principle of the “hot box” (see September 27, 1816), thus increasing the tanks’ capability of collecting and retaining heat. He calls his invention the “Climax.” He first markets it to Eastern “gentlemen” whose wives have gone on holiday for the summer, leaving them to their own devices. Kemp sells his heaters by claiming that they will reduce the effort needed to perform housekeeping duties, especially for men unaccustomed to lighting the gas furnace or stove to heat water. Later, Kemp will find a brisk market for his Climax heaters in warmer states such as California. By 1897, a third of the households in Pasadena will use the Climax to heat water in their homes. [California Solar Center, 2001; US Department of Energy, 2002 ]