Grid-Connected PV System
In a grid-connected PV system the electricity generated from the sunlight is directly transferred to the electricity utility grid. The size of grid-connected system may vary from residential with the capacity of 2-10 Kwp to a solar power station having the capacity of 10s of Gwp.
The DC power developed from the PV array must be converted to AC so it can be transfered to the electric grid. To do so, a grid-controlled inverter is used in this system.
When you are using this type of PV system it is essential to ensure that the system will not feed electricity to the electric grid if it is down for repair. Therefore saftey control systems are also required.
How the Grid-Connected PV System Works
In the diagram to the right is a simple explanation of the workings of a grid connected system. The electricity generated from the PV array is transferred to the primary component of the system, a power conditioner unit or inverter. This component converts the DC power developed in PV array to AC power for household usage. The AC power is transferred to the distribution panel. The distribution panel distributes the electricity throughout your home, and if the electricity quantity is greater than the on-site demand it feeds the extra amount of electricity to the electric grid (and you get a credit from the electric company on your bill).
Components of Grid-Connected PV System
This is the most important component for all types of PV systems. It consists of photovoltaic cells. When the sunlight hits one the silicon wafers in it generate electricity. The energy of sunlight excites the free electrons of the silicon and releases them from their bonds to generate electricity.
Power Conditioner or Inverter
The next component used in the process is inverter. This is used for converting DC power to AC to use in households and to feed in electric grid. This inverter also synchronizes and improves electricity quality so that it can be freely fed to the grid.
The distribution panel is a component to divide the electric power to the AC loads and electric grid.
This is nothing but the electric devices that require AC power to work. The AC power from the distribution panel is then supplied to the household electric devices for the further use of electricity.
The electricity that exceeds the demand is transferred to the electric grid so that it can be used in other areas. If the PV system may not develop the required amount of electricity then this component is also used for fulfilling the demand from other external electric source.