Photovoltaic systems are what most people think of when they consider installing solar power systems on their home. They consist of solar panels usually mounted on the roof to absorb and convert sunlight into electricity.
Photovoltaic systems rely on a semiconductor that serves as the power-generating component of the solar panel. The semiconductor – usually a type of silicon – is a unique type of conductor because it contains electrons that produce an electric current when struck by sunlight. The current is configured to flow in a particular direction either to provide direct power to your house; into an alternating current, as with electrical grids; into a battery for later consumption; or into a combination of these outlets.
A photovoltaic system usually consists of multiple solar panels depending on the amount of energy required. A simple array may consist of several solar panels to power a household appliance, or it can be broader in scope to provide energy to the entire house.
How a Photovoltaic System Works
A photovoltaic system consists of solar panels or arrays, and balance of system components which support and facilitate the transfer of electricity from solar panels and arrays.
Cells, Panels, and Arrays
Solar panels consist of photovoltaic cells that absorb sunlight. Once absorbed, the sunlight knocks electrons lose in the semiconductor material and allows the electrons to flow freely. The cells contain electric fields that direct the freed electrons to flow in a specific direction, creating a current. That current forms the basis of the electrical output generated by a solar cell. Along with the cell’s voltage, the current determines the cell’s ultimate wattage.
Balance of System Components (BOS)
A photovoltaic system is incomplete without other materials known as balance of system (BOS) components, which essentially make the electricity generated by solar panels usable. BOS components typically include inverters, mounting or support racks, wiring, switches, and batteries.
Generally, photovoltaic systems can be classified as either stand-alone or grid-connected systems.
Standalone systems rely solely on the power generated by a photovoltaic system for its electricity. A solar-powered watch, for example, draws all of its power from the electrical output of a solar cell. Standalone systems usually incorporate batteries to store electricity that isn’t immediately used, enabling the use of the solar-powered device to operate even when sunlight is unavailable. A PV-hybrid system supplement the power generated from solar panels through the use of an auxiliary power source such as wind, an engine-generator, or utility power.
Grid-connected systems are linked to electric utility grids that supply power to numerous outlets, such as communities and businesses. A grid-connected system uses an inverter that converts the DC (direct current) energy provided by a photovoltaic system into AC (alternating current) power that is consistent with the grid’s voltage and power quality requirements.
Background and Photovoltaic Effect
Photovoltaic systems are founded on the photovoltaic effect, in which voltage or electric current is created by exposure to light. Photovoltaic systems can trace their origin back to 1839, when French physicist Edmond Becquerel discovered the process of using sunlight to produce an electric current in a solid material.