Solar Hot Water Lessons Learned: 1977 til Today
http://solarindustries.com/book.html#.UN37VqzNl8F
The following is an exerpt from a book about the history of solar heating and swimming pools:
Solar pool collectors are made from polypropylene. To create a 4' x 12' pool collector, 26.6 pounds of natural gas and petroleum are used. If this gas and oil was burned, it would create 410,800 BTU's. A 4' x 12' pool collector will produce 410,000 BTU's in less than TEN DAYS. The BTU conversion to KWH's in one year from ten 4' x 12' collectors is 43,262 KWH. At $.10 per KWH, this results in a savings of $4,326! Natural gas at $1.00/therm or LP gas at $1.40/gallon would cost $2,163 to generate 410,000 BTU/day/year. A solar pool heating system with
ten 4' x 12' collectors installed with an automatic comfort control, would cost from $4,900 to $5,800. Clearly, solar pool heating is the most cost effective use of solar energy on Earth. Pool collectors will typically last from 12 to 20 years - more than two to three times the life of a gas heater, electric heater, or swimming pool heat pump.