| Solar Photo Voltaic Modules are best known as a | | | | The power output of photovoltaic systems for |
| method for generating electric power by using | | | | installation in buildings is usually described in |
| solar cells to convert energy from the sun into | | | | kilowatt-peak units (kWp). |
| electricity. The photovoltaic effect refers to | | | | In transport: |
| photons of light knocking electrons into a higher | | | | PV has traditionally been used for auxiliary power |
| state of energy to create electricity. | | | | in space. PV is rarely used to provide motive |
| In buildings: | | | | power in transport applications, but is being used |
| Building-integrated photovoltaic (BIPV) are | | | | increasingly to provide auxiliary power in boats |
| increasingly incorporated into new domestic and | | | | and cars. Recent advances in solar race cars, |
| industrial buildings as a principal or ancillary source | | | | however, have produced cars that with little |
| of electrical power, and are one of the fastest | | | | changes could be used for transportation. |
| growing segments of the photovoltaic industry. | | | | Standalone devices: |
| Typically, an array is incorporated into the roof or | | | | Until a decade or so ago, PV was used frequently |
| walls of a building and roof tiles with integrated PV | | | | to power calculators and novelty devices. |
| cells can now be purchased. Arrays can also be | | | | Improvements in integrated circuits and low |
| retrofitted into existing buildings; in this case they | | | | power LCD displays make it possible to power |
| are usually fitted on top of the existing roof | | | | such devices for several years between battery |
| structure. Alternatively, an array can be located | | | | changes, making PV use less common. In |
| separately from the building but connected by | | | | contrast, solar powered remote fixed devices |
| cable to supply power for the building. | | | | have seen increasing use recently in locations |
| Where a building is at a considerable distance from | | | | where significant connection cost makes grid |
| the public electricity supply (or grid) - in remote or | | | | power prohibitively expensive. Such applications |
| mountainous areas – PV may be the | | | | include parking meters, emergency telephones, |
| preferred possibility for generating electricity, or | | | | temporary traffic signs, and remote guard posts |
| PV may be used together with wind, diesel | | | | & signals. |
| generators and/or hydroelectric power. In such | | | | Rural electrification: |
| off-grid circumstances batteries are usually used | | | | Developing countries where many villages are |
| to store the electric power. | | | | often more than five kilometers away from grid |
| In locations near the grid, however, feeding the | | | | power have begun using photovoltaic. In remote |
| grid using PV panels is more practical, and leads to | | | | locations in India a rural lighting program has been |
| optimum use of the investment in the | | | | providing solar powered LED lighting to replace |
| photovoltaic system. This requires both regulatory | | | | kerosene lamps. The solar powered lamps were |
| and commercial preparation, including net-metering | | | | sold at about the cost of a few months’ |
| and feed-in agreements. To provide for possible | | | | supply of kerosene. Cuba is working to provide |
| power failure, some grid tied systems are set up | | | | solar power for areas that are off grid. These are |
| to allow local use disconnected from the grid. Most | | | | areas where the social costs and benefits offer |
| photovoltaic are grid connected. In the event the | | | | an excellent case for going solar though the lack |
| grid fails, the local system must not feed the grid | | | | of profitability could relegate such endeavors to |
| to prevent the possible creation of dangerous | | | | humanitarian goals. |
| islanding. | | | | |