Grid Connected Rooftop Solar System
Photovoltaic (PV) systems are generally divided into two major categories: grid-connected (also known as grid-tied) systems that are interfaced to an electricity grid and stand-alone systems that are self-contained. Since the 1990s the market has shifted decisively toward PV power plants and installations on buildings connected to an electricity grid. In 2000 grid-connected PV had overtaken stand-alone systems in global market share, and in 2016 more than 98% of solar cell production was being deployed in grid-connected systems.
An on-grid or grid-tied solar system is a system that works along with the grid. This means that any excess or deficiency of power can be fed to the grid through net metering. Many residential users are opting for an On-grid solar system as they get a chance to enjoy credit for the excess power their system produces and save on their electricity bills. You will always have power either from the solar system or from the grid. They do not have batteries.
Essential Components of Grid-Connected PV Systems
In more detail the various items numbered 1-10 in the figure have the following functions:
1.Solar Panel – Solar panels are the main components of the on-grid solar system. They comprise more than 50% of the total cost of a solar system and are the components that capture solar energy and convert solar energy into electrical energy.
2. Solar Inverter – At the heart of the grid-connected system, the inverter extracts as much DC power as possible from the PV array and converts it into AC power at the right voltage and frequency for feeding into the grid or supplying domestic loads. Solar Inverters help in converting the DC output produced from the solar panel into AC supply.
3. Panel Stand – Panel stands are also a major component of the entire solar system. Some people do not give much heed to this component and try and save a few bucks by using a low-quality stand. However, remember that this stand will support the solar panels and if the stand is not sturdy your solar panels could just fall resulting in a heavy loss. It is the skeletal structure holding the panel in the proper position. These stands are generally made of aluminum or galvanized iron. Solar panel stands can be fixed or movable to track the sun.
4. Solar Wire – Solar Wire or Solar Cable is the medium through which electricity is transferred from solar panels to the inverter. Generally, there are two types of wires in the market, such as AC Wire and DC Wire. It is called a solar wire as the solar panel output is DC current.
5. DCDB / ACDB – DC Distribution Board or DCDB is used for connecting the output power from the solar panel to the input of the inverter while AC Distribution Board or ACDB distributes the electrical power from a solar inverter to the AC load system through an energy meter.
6. Earthing Kit – An earthing kit is used to protect the on-grid solar system from thunder.
7. Lighting Arrestor – Lightning Arrestor is used to protect the on-grid solar system from lightning
8. Net Meter & Solar Meter – Net metering is a special metering and billing agreement between utilities and their customers, which facilitates the connection of small, renewable energy-generating systems to the power grid. It is an important component in an on-grid solar system as it keeps the reading to claim credit in your future electricity bills. For solar energy, Net Metering is also very important as solar energy unlike other forms of renewable energy is produced a lot in residential and commercial segments.
9. Safety Equipment – To safeguard the solar system from damages such as lightning and other faulty conditions, protection devices are used. These comprise of surge arrestor, circuit breaker, grounding method, etc.
10. Installation Accessories – These include installation accessories like wires, cabling, mounting structures, junction boxes, etc.
The adoption of domestic rooftop installations is mushrooming in developed countries in response to the falling prices of solar PV modules, the support of governments, and the enthusiasm of citizens to do something positive about global warming. Larger grid-connected systems, for example, those installed in homes, schools, offices, public buildings, and factories, extend the power scale from hundreds of kilowatts up to megawatts (MW). All have the advantage of generating solar electricity where it is needed, reducing the losses associated with lengthy transmission lines and cables. And at the top of the grid-connected power scale come multi-megawatt power plants, generally remote from individual consumers, which send all their power to the grid.
