Solar Photovoltaic System uses solar cells to convert light into electricity. A PV system consists of PV modules and balance of systems (BOS). Balance of systems includes module support structure, storage, wiring, power electronics, etc.

DC (direct current) electricity is generated when solar radiation strikes the PV module. Power can be used in any DC load directly during this generation. But the generation exists during daytime. So, some storage device is needed to run the system at night or in low sunshine hour. Again this power cannot be used to run any AC (alternate current) load. Inverter has to be used to convert DC into AC.

Solar PV systems are categories into

 

Stand-alone PV systems :

Stand-alone systems are not connected with utility power lines and these are self sufficient systems. These systems could either be used to charge the batteries that serve as an energy storage device or could work directly using the solar energy available in the daytimes. These systems consist of the following:

  • Solar panels mounted on the roof or in open spaces. Photovoltaic modules produce direct current (DC) electrical power.
  • Batteries to store DC energy generated by the solar panels.
  • Charge controller to prevent overcharging the battery.
  • Inverter to convert electricity produced by the system from DC to AC power.

The following diagram shows PV system powering AC loads with battery bank. DC loads can also be connected directly to the battery bank. It is also possible to power the AC load without battery, but in that case it would be confined only to daytime when solar radiation is sufficient to generate required electricity.

Stand-alone PV System

 

Grid connected PV systems :

A grid connected photovoltaic system will be interacted with utility grid. The main advantage of this system is that power can be drawn from the utility grid and when power is not available from grid, PV system can supplement that power. These grid connected systems are designed with battery or without battery storage. These systems consist of the following:

  • Solar panels mounted on the roof or in open spaces. Photovoltaic modules produce direct current (DC) electrical power.
  • Batteries to store DC energy generated by the solar panels.
  • Charge controller to prevent overcharging the battery.
  • Specially designed inverter to transform the PV generated DC electricity to the grid electricity (which is of AC) at the grid voltage.

The following diagram shows PV system powering AC loads. This system is connected to utility power supply and having battery storage for backup.

Grid connected PV System

 

Hybrid systems :

System with more than one source of power is called Hybrid system. It is often desirable to design a system with additional source of power. The most common type of hybrid system contains a gas or diesel powered engine generator. Another hybrid approach is a PV/Wind system. Adding a wind turbine to a PV system provides complementary power generation. These systems consist of the following:

  • Solar panels mounted on the roof or in open spaces. Photovoltaic modules produce direct current (DC) electrical power.
  • Batteries to store DC energy generated by the solar panels.
  • Charge controller to prevent overcharging the battery.
  • Specially designed inverter to transform the PV generated DC electricity to the grid electricity (which is of AC) at the grid voltage.

The following diagram shows PV system powering AC loads. This system is connected to utility power supply & diesel generator and having battery storage for backup.

Hybrid System