What is solar photovoltaic system?
Solar photovoltaic system is the active solar technology which uses suns energy as fuel and produces electricity using solar cells encapsulated in panels called solar modules. There are two types of solar pv systems used to generate electricity from sunlight: Grid-connected systems and Stand-alone systems.
Grid-connected solar PV system
The grid-connected pv system is connected to main public grid and works only when the grid is available. The generated solar energy is used to power the loads in the building and the surplus is fed onto the public grid. When the pv system is not producing enough electricity to power all loads in the building, for example at nights, and raining days, then the electricity is supplied by the grid as usual.
How it works
The solar modules produce DC electricity when sunlight is available. This electricity is fed by cables to an inverter via a DC-switch. The inverter converts this DC electricity to AC electricity which is compatible with the connected grid. The AC output of the inverter is connected to the main fuse box in the building via an AC-switch. The energy is then consumed by the loads in the building and the surplus is fed onto the public grid.
In some countries, the grid company buys this electricity from the owner of the pv system and sell it to other customers.
If there is power outage, the PV system will be automatically disconnected from the public grid and will not provide protect against a power cuts. This is a standard safety feature in the inverter to prevent that the PV system fed electricity onto the grid from “wrong side” during power outage.
Stand-alone solar PV System
Stand-alone PV system uses batteries to store the energy generated by the solar modules during daytime. The energy yield of the stand-alone system is matched to the energy demand of the connected loads. Since the most energy is not needed during daytime, it is stored in rechargeable batteries and it is used when the sun is not shining and the modules are not producing enough electricity to power all electrical appliances, like night or cloudy and raining days. It is important that the solar PV system is properly sized to produce the needed electricity to store it in the batteries to power the loads at nights and cloudy days.
How it works
The DC electricity produced by the solar modules in a typical stand-alone pv system is used to charge batteries via a solar charge controller, which is connected to the solar modules. The charge controller is then connected to a battery bank and charges it by the power from the solar modules. The battery bank is then connected to an inverter, which converts the DC power from the battery into AC electricity. All AC loads connected to the Stand-alone system are then connected to the inverter, while all DC appliances are connected direct to the charge controller.
