The number of PV installations on buildings connected to the electricity grid has grown in recent years. Government subsidy programs (particularly in Germany and Japan) and green pricing policies of utilities or electricity service providers have stimulated demand. Demand is also driven by the desire of individuals or companies to obtain their electricity from a clean, non-polluting, renewable source. These consumers are usually willing to pay only a small premium for renewable solar energy. Increasingly, the incentive is an attractive financial return on the investment through the sale of solar electricity at premium feed-in tariff rates.
In solar energy systems connected to the electricity grid, the PV system supplies electricity to the building, and any daytime excess may be exported to the grid. Batteries are not required because the grid supplies any extra demand. However, to be independent of the grid supply, battery storage is needed to provide power at night.
Holiday or vacation homes without access to the electricity grid can use solar energy systems more cost-effectively than if the grid was extended to reach the location. Remote homes in sunny locations can obtain reliable electricity to meet basic needs with a simple system comprising of a PV panel, a rechargeable battery to store the energy captured during daylight hours, a regulator (or charge controller), and the necessary wiring and switches. Such systems are often called solar home systems (SHS).
On an office building, roof areas can be covered with glass PV modules, which can be semi-transparent to provide shaded light. On a factory or warehouse, large roof areas are the best location for solar modules. If the roof is flat, then arrays can be mounted using techniques that do not breach the weatherproofed roof membrane. Also, skylights can be partially covered with PV.
The vertical walls of office buildings provide several opportunities for PV incorporation, as well as sunshades or balconies incorporating a PV system. Sunshades may have the PV system mounted externally to the building, or have PV cells specially mounted between glass sheets comprising the window.
For many years, solar energy has been the power supply choice for industrial applications, especially where power is required at remote locations. Because solar energy systems are highly reliable and require little maintenance, they are ideal in distant or isolated places.
Solar energy is also frequently used for transportation signaling, such as offshore navigation buoys, lighthouses, aircraft warning light structures, and increasingly in road traffic warning signals. Solar energy is used to power environmental monitoring equipment and corrosion protection systems for pipelines, well-heads, bridges, and other structures. For larger electrical loads, it can be cost-effective to configure a hybrid power system that links the PV with a small diesel generator.
Remote buildings, such as schools, community halls, and clinics, can benefit from solar energy. In developing regions, central power plants can provide electricity to homes via a local wired network, or act as a battery charging station where members of the community can bring batteries to be recharged.
PV systems can be used to pump water in remote areas as part of a portable water supply system. Specialized solar energy water pumps are designed for submersible use or to float on open water. Large-scale desalination plants can also be PV powered using an array of PV modules with battery storage.
PV systems are sometimes best configured with a small diesel generator in order to meet heavy power requirements in off-grid locations. With a small diesel generator, the PV system does not have to be sized to cope with the worst sunlight conditions during the year. The diesel generator can provide back-up power that is minimized during the sunniest part of the year by the PV system. This keeps fuel and maintenance costs low.