Understanding Solar Technologies: A Solar Primer
Most applications for solar in the home or office fall into one of three categories. Because each application has a different need or requirement for the solar energy, the technology is different for each.
·Solar Water Heating – Sometimes also called Domestic Hot Water (DHW), collectors designed for solar water heating are made of glass, copper and insulation. They are designed to heat relatively small amounts of water (40 to 80 gallons in a home) quickly, to high temperatures suitable for bathing, laundry and dish-washing. Just as with an electric water heater, most solar water heaters require a circulating motor and a storage tank.
·Solar Pool Heating – Pool heating technology requires that large amounts of water (thousands of gallons) be heated to more moderate, comfortable temperatures which are typically lower than bathing requirements. Thus, this technology is designed to circulate high volumes of water slowly & repeatedly through polypropylene collectors. Since high temperatures are not desired, glass and copper are not needed to overly heat the water. Solar pool heating technology is similar to the water that is warmed in your garden hose when it sits in the sun; it therefore requires far fewer enhancements than other forms of solar energy.
·Solar Electric – Demand for electricity requires vast amounts of sophisticated solar collection. Also known as photovoltaics (PV), solar electric technology features large arrays of collectors made up of silicon-coated cells. When sunlight strikes the surface of a PV cell, electrical fields are directed to electrons, resulting in a flow of current. PV electric systems require major components to properly conduct, control, convert, distribute, and store the energy produced by the array – items such as a power inverter, battery bank, system and battery controller, auxiliary energy sources and sometimes the specified electrical load (appliances). Photovoltaic systems can be designed to provide DC and/or AC power service, can operate interconnected with or independent of the utility grid, and can be connected with other energy sources and energy storage systems. The current high cost of PV modules and equipment (as compared to other solar applications) is the primary limiting factor for this technology today.