Solar Water Heating
Solar water heating systems utilize the energy of the sun by heating either water or a heat transfer fluid in collectors. These types of systems typically reduce the need for conventional water heating by two-thirds. There are many different variations of solar water heating systems and various components that can be added to a system to increase efficiency.
Some systems are "open loop" (the domestic water itself is directly heated) and some are "closed loop" (a heat transfer fluid is heated by the collector and the heat is passed on to the domestic hot water by means of a heat exchanger). Some systems are "active", using moving parts such as pumps and valves, and others are "passive", using no mechanical or moving parts.
Solar hot water heaters have many economic advantages. The various types of solar water heaters permit the consumer to select the most appropriate system to be used with their conventional system. Although the initial cost of solar water heaters is higher than conventional water heaters, solar energy is free. A well-installed solar hot water heater in a home can supply sixty to seventy percent of the energy needed to heat water for a year. In addition, the original cost of the solar heating system (providing it has been installed correctly) will be paid off within four to eight years following installation. The price of solar water heaters is competitive with electric water heaters, and is also economically advantageous as a pre-heater for oil, natural gas, or propane water heaters.