About On-Grid PV Systems
A grid connected system is connected to a large independent grid (typically the public electricity grid) and feeds power into the grid. Grid connected systems vary in size residential (2-10kWp) to solar power stations (up to 10s of MWp).
This is a form of decentralized electricity generation. In the case of residential or building mounted grid connected PV systems, the electricity demand of the building is met by the PV system. Only the excess is fed into the grid when there is an excess.
The feeding of electricity into the grid requires the transformation of DC into AC by a special, grid-controlled solar inverter.
Solar power systems that are connected to the electricity grid otherwise known as grid connected, grid tied, on-grid photovoltaic systems generate electricity for your home or place of work and feed excess energy produced back into the electricity grid system.
Grid connected systems are designed to replace all or a portion of the building’s total electricity needs. The energy generated by such a system is used first within the home, and surplus energy can then be sold back to the grid. The surplus energy “spins the electric meter backwards” when the energy produced by the solar PV system is greater than that being consumed by the home. In actual fact the utility company will normally install an export meters which measure the amount of electricity generated by the solar PV system.
Advantages and Disadvantages of Grid Connected Systems
There are two types of grid connect systems;
a- without battery backup on-grid systems,
b- battery backup on-grid systems.
Grid connected systems without a battery consist of two main components, a solar PV array and a grid-connect inverter. If the utility grid fails then the solar PV array has no way of providing power as the inverter will automatically disconnect itself the utility grid.
Grid-tied systems with a battery backup also have an array and a grid-tied inverter, but include the addition of a battery bank and charge controller. Systems with a battery bank can provide power in the event of the electricity (utility) grid failure.
There are many advantages of using a grid connected system
- Simple to install,
- High efficiency,
- Reliable,
- Flexible…
If we examine a typical household installation, please refer to the diagram below a number of essential components comprise the solar photovoltaic system.
1) Solar panels - one or more modules wired together to generate a specific voltage and current
2) Combiner (junction) Box - allows termination of the solar panels
3) Grid tie inverter - device that converts DC (direct current) to AC (ALTERNATING Current)
4) Import / export meter - records energy generated and consumed
5) Grid connect point - distribution board connection
6) Electrical load - appliances that are powered by ALTERNATING current.
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Hybrid Power System
