Photovoltaic Solar System

Technology Profile - Solar Photovoltaic (PV)

Photovoltaic is a convenient, quiet and clean way of providing long-term electrical power, both for remote locations and as a form of distributed power for houses connected to the electricity grid.
This technology converts light energy directly into electricity by transferring sunlight "photon" energy into electrical energy.
This conversion takes place within cells of specially fabricated semiconductor crystals. The main construction types of PV cells are:

• Monocrystalline - this silicon crystal structure is formed by melting semiconductor grade silicon, and causing a single crystal growth around a small "seed" crystal

• Polycrystalline - this produces a multiple-grained structure by controlling the cooling rate of silicon material that has been melted in a crucible

• Amorphous or thin-film

New enhancements to crystalline cells include buried grid cells, triple-junction cells and "Slivercr" cells, which provide higher efficiency or lower production costs.
A number of cells (generally 36) make up a "PV module", also known as a solar panel. PV modules can be interconnected to form arrays of different voltage and current capacities. Photovoltaic systems produce DC electricity, so power conditioning equipment such as inverters are required to produce AC for normal household appliances. Power output is very dependent on the solar radiation hitting the PV cells, so modules must be installed to face north and minimise shading to ensure maximum possible energy output.
Tracking systems can sometimes be used to allow the modules to point toward the sun and provide extra energy output. Photovoltaic systems are an ideal match to many summer electrical loads, producing maximum power when demand is also highest, so they are being increasingly used in grid-connected systems as distributed generators. In off-grid systems, some form of energy storage will be required for night or periods of low sunlight. This is usually in the form of battery storage.
While panels are the most commonly installed format for PV cells, there is large potential for "Building-integrated PV" (BiPV), where photovoltaic modules are incorporated into building fabrics or roof tiles. Concentrating systems allow small high-efficiency modules to be used, though extra cooling and specialised mounting construction are required.