Photovoltaics are expensive to produce because of the high cost of semiconducting materials. Cost reductions can be achieved by reducing manufacturing costs. As manufacturing capacity increases, costs of manufacturing decrease. Manufacturers aim to achieve the break-even cost for a photovoltaic system, at which the cost of the electricity it produces is equal to the cost of electricity from an alternative source plus the cost of delivering this electricity to the site. The distance a power line needs to be extended to equal the installation cost of a photovoltaic system is called the break-even distance.
Solar arrays work well for generating power in space and power virtually all satellites. Most satellites and spacecraft are equipped with crystalline silicon or high-efficiency Group III-IV cells, but recently satellites have begun using thin-film amorphous-silicon-based solar panels.
Grid-connected Photovoltaic Systems
Grid-connected photovoltaic systems, also called grid interface systems, supply surplus power back through the grid to the utility, and take from the utility grid when the home system’s power supply is low. These systems remove the need for battery storage, although arranging for the grid interconnection can be difficult. In some cases, utilities allow net metering, which allows the owner to sell excess power back to the utility.
Stand-Alone Photovoltaic Systems
Stand-alone systems produce power independently of the utility grid. In some off-the-grid locations as near as one-quarter mile from the power lines, stand-alone photovoltaic systems can be more cost-effective than extending power lines. They are especially appropriate for remote, environmentally sensitive areas, such as national parks, cabins, and remote homes. In rural areas, small stand-alone solar arrays often power farm lighting, fence chargers, and solar water pumps, which provide water for livestock. Direct-coupled systems need no electrical storage because they operate only during daylight hours, but most systems rely on battery storage so that energy produced during the day can be used at night. Some systems, called hybrid systems, combine solar power with additional power sources such as wind or diesel.