List of Solar Power Systems

Solar Electric

• Most people think of electricity when they hear the words "solar power." Solar-electric panels, technically referred to as photovoltaic (PV) modules, convert sunlight into electrons. Historically, most solar electric systems were designed to provide electricity in areas where utility power wasn't available. As of 2000, utility interconnected, or grid-tied systems, have dominated the market.

Stand-Alone

• Stand-alone, or off-grid, PV systems produce electricity without input from a utility company. The simplest design consists of a solar module and a load such as a water pump. The solar module generates electricity when the sun is shining to run the pump. Most stand-alone PV systems use a battery bank to provide power at night when the sun isn't out.

  A stand-alone system is designed to provide 100 percent of the electrical load, so the time spent determining the amount of power needed and for what duration is critical. Well-designed off-grid systems use generators for emergency backup charging and inverters to convert direct-current (DC) electricity into alternating current (AC).

Grid

• Grid-tied systems generate electricity in the same way as off-grid systems but require power from a utility company. A grid-tied system consist of solar modules and a grid-tied inverter A grid-tied system is the most efficient and economical type of PV system. The purpose of a grid-tied system is to offset the amount of electricity purchased from the utility.

  Determining the load profile is not as critical as with off-grid systems because the utility power is available to provide backup. Grid-tied systems use net-metering, which is the ability to sell excess electricity back to the utility company. Batteries can be designed into a grid-tied system to provide power during blackouts, but these increase the system cost and lower the overall efficiency.

Solar Thermal

• Unlike PV panels, solar-thermal panels use the sun's heat rather than light to generate power. A simple example of solar-thermal power is how water heats up in a garden hose exposed to sunlight. Solar-thermal systems are used to heat water for household use and to heat swimming pools.

  Thermal systems for pools use solar collectors and existing pool pumps. The water is pumped through collectors, which are heated by the sun, then pumped immediately back into the pool. Solar-thermal collectors for domestic use can connect to an existing water heater, often providing enough hot water to keep the conventional heater from turning on.