The conversion of solar radiation to usable electric power is a process of high technical complexity. Photovoltaic modules are the core of the system, but they are only one of the components necessary to carry out the energy conversion process - by themselves, they are incapable of producing a safe, usable and reliable electric output. This article will describe the main components of a solar photovoltaic system.
This is the core of the system, composed of several solar modules which are in turn composed of solar cells. Each solar cell is an individual energy conversion unit, which produces a DC voltage whenever it receives light. It is important to note that photovoltaic modules generate voltage in response to any light source, not only sunlight. By connecting the modules in one or more series circuits, their DC voltage output can be aggregated into a single electric supply.
Crystalline silicon PV modules compose the majority of the photovoltaic market. There are also emerging alternatives such as thin-film Cadmium Telluride modules, but they account for only a small percentage of the market. Regardless of the technology, the working principle is the same: using a material that is capable of providing a voltage output in response to incident light.
Solar PV systems occasionally produce energy at times when it isn't needed, for example if a home is empty at the moment of production. If this happens, the surplus can be either sold to the electric utility or stored in batteries. There are two main reasons for deciding to use battery storage:
Batteries tend to raise the cost of a PV system considerably. This means that savings are only feasible if there is a drastic energy price increase during peak demand hours. Otherwise, batteries actually make solar power more expensive.
This part of the system has three main functions:
For safety reasons, electric systems must be equipped with a manual disconnection device. This is normally used to protect technical personnel from electric shock during system maintenance. In addition, a manual disconnection switch allows any user to interrupt the circuit if there is an emergency.
This is where all electric loads in the building are connected, and protected with circuit breakers. Once the output from the PV system has been converted to AC power of the adequate frequency, it can be connected to the main panel to provide energy along with the electric utility.
When PV systems are implemented, the electric meter must be upgraded to a model with net metering capabilities. That is, the meter must be able to measure the energy flow and its direction. This allows the exported kWh to be subtracted from the consumed kWh when the homeowner is billed by the electric utility company.