Solar Hot Water
Solar water heating for washing and bathing is an excellent solar application, perhaps more than central heating because the primary need for central heating is at night and in winter when solar gain is lower. Supply and demand are simply better matched when heating water. In many climates, a solar hot water system can provide up to 65% of domestic hot water energy. This can include domestic non-electric concentrating solar thermal systems.

Economics, Energy, & the Environment
The typical 50 gallon electric water heater uses 11.1 barrels of oil a year, which translates into the same amount oil used by a typical 4 door sedan driven by the average consumer. Electric utility companies often provide electricity by burning and releasing energy from fuels such as oil, coal, and nuclear energy. An electrical home hot water heater sits on an electrical grid and may be driving the use of unclean fuels on the other end of the grid. Solar water heating systems can significantly reduce such electricity consumption.

When calculating the total cost to own and operate, a proper analysis will consider that solar energy is free, thus greatly reducing the operating costs, whereas other energy sources, such as gas and electricity, can be quite expensive over time. Thus, when the initial costs of a solar system are properly financed and compared with energy costs, then in many cases the total monthly cost of solar heat can be less than other more conventional types of hot water heaters.

A Wall Street Journal Video on Solar Hot Water