The term "photovoltaic" means the direct conversion of light into electrical energy using solar cells. Semiconductor materials such as silicon, gallium arsenide, cadmium telluride or copper indium diselenide is used in these solar cells.
Every day, light hits your roof solar panels with particles of sunlight called photons. The solar panels convert those photons into electrons of direct current ("DC") electricity. The electrons flow out of the solar panel and into an inverter. The inverter converts that "DC" power (commonly used in batteries) into alternating current ("AC") power. AC power is the kind of electricity that your television, computer, and toaster use when plugged into the wall outlet.
A net energy meter tracks all the power the solar system produces. Any excessive production that is not used right away will go back to the national grid through the meter or to the backup system (depending on the type of PV system used). At times when the system is not producing more than the the building's needs (at night or on cloudy days) electricity will be used from the national grid as normal or from the stored energy in the backup system or from the credit in the National Grid. The electricity bill will be the net consumption for any given period and the credit.
- PV panels provide clean - green energy. During electricity generation with PV panels, there is no harmful greenhouse gas emissions, thus solar PV is environmentally friendly.
- The fuel (sunlight) is abundant and free.
- PV panels are totally silent, producing no noise at all; consequently, they are a perfect solution for urban areas and for residential applications.
- PV systems are very safe and highly reliable, the estimated lifetime of a PV module is 30 years.
- The PV system is easily expandable and even transportable in some cases.
- The PV system requires minimal maintenance and is almost negligible compared to the costs of other power generating technologies.
- The system can save up to 100% of your electricity bill, when it produces excess electricity, the electricity will be saved at the national grid and used at times of low sunlight.
Stand-alone (off-grid) PV systems are independent photovoltaic systems. Typical off-grid applications are used to bring access to electricity in rural areas (remote locations, desert locations). Rural electrification means either small solar home system (covering basic electricity needs in a single household), or larger solar mini-grids, which provide enough power for several homes.
The system should be connected to a battery via a charge controller. An inverter can be used to provide AC power, enabling the use of normal electrical appliances.
An off-grid system is light and can be easily transported and installed. Its lifespan is quite long and it requires minimum maintenance, it only needs occasional inspection and cleaning.
DC (direct current) generated by the PV panels is converted by the “inverter” to AC (alternating current).
The AC is the type of power used by appliances in any building and the power generated by PV systems/plants is of the same high quality that is provided by the national electric utility.
Power will be distributed to the whole site by the existing distribution panel and the excess output will be fed back into the national grid under the “net metering” regulation .