Solar panels is the common name given to photovoltaic modules which are an assembly of photovoltaic cells, also known as solar cells. The solar panel can be used in conjunction with other panels in a larger photovoltaic system to generate electricity for homes and commercial premises.
A single solar panel can only produce a certain amount of electricity, several panels are required to produce larger electrical power capacity which is known as a photovoltaic array. A good solar panel installation usually includes an array of panels, an inverter, batteries and interconnection wiring. Photovoltaic systems are used for on/ off grid applications, as well as for solar panels on spacecraft.
Theory & Construction
Solar Panels use solar energy to generate electricity through photo-voltaic effect. Most modules use crystalline silicon, which is derived from silicon, a commonly used semi-conductor.
For cells within a panel to function, they should:
- have electrical connection to each another and to the system
- be protected from damage in particular against hail impact, wind and snow loads
- be protected from damp, which corrodes metal and decreases performance and lifetime.
Most panels are rigid, however, there are some flexible modules available. Since cell heating reduces the panels production efficiency it is desirable to reduce the heating effect. As few modules have features to decrease temperature, installers should try to provide good ventilation behind the module.
Newer panel designs concentrate light, using lenses or mirrors, onto an array of small cells. This allows designers to use cells with a very high cost per unit area in a cost competitive way. Sunlight conversion rates vary between five an eighteen percent in commercial production solar panels. As of January 14, 2009 a world record efficiency level of 41.1% has been reached.
Thin-film Solar Panels
Third generation solar cells are advanced thin-film cells. They produce high-efficiency conversion at low cost.
Rigid thin-film panels
In rigid thin film modules, the cell is created directly on the rigid glass structure, and the connections are created at the same time. The glass is laminated to a front or back sheet of glass.
Flexible thin-film panels
Flexible thin film cells and modules are created by depositing the photoactive layer on a flexible structure. The cells are laminated into panels on a transparent colorless sheet on the front side.
Solar Panel Performance and Lifetime
Solar panels must withstand all temperatures, rain and hail for many years. Many panel manufacturers offer warranties that guarantee electrical production for ten years at ninety percent of rated power output and twenty five years at eighty percent. Many houses in the United States are now have solar panels. Forty square meters are required to supply all the electricity for a normal house.