On-Grid solar power system: Advantages, Types, Structure
On-Grid solar power systems are one of the ways to strengthen the national power grid and prevent electrical pressure on power plants during peak days. Today, On-Grid solar power systems have been installed in many countries of the world in small units from 1 kW to 5 kW on the roof of residential houses and in larger units such as solar power plants.
In a country like Oman, where the number of hot days in a year and the amount of sunlight during the day is high, using On-Grid solar power systems can reduce the pressure on the national power grid and prevent power outages on hot days.
Advantages of On-Grid solar power systems
- They can be installed faster than other fossil fuel and renewable power plants.
- Electricity production of On-Grid solar power systems is guaranteed and is the most effective way to reduce consumption during peak hours.
- On Grid power plants, while supplying electricity to small regional networks, do not need to establish long high voltage lines to transmit electricity to the national electricity grid, and therefore, there is no need for high cost of constructing transmission networks.
- They are stabilized in terms of energy production and are used for long-term use with high reliability.
- The guaranteed purchase rate of electricity leads to more revenue than the free purchase rate by the retail market.
- On Grid solar systems provide 30 to 60 percent of electricity consumption.
- Due to not using fossil resources and preventing pollution, they are considered as clean power plants.
- Unlike fossil power plants, whose electricity price is dependent on the price of oil, in solar power plants, the lack of price fluctuations caused by fuel price changes stabilizes the price of electricity consumed in the long term.
- The cost of maintenance and repair of solar power plants is negligible, while they have a long life because of not much depreciation.
The structure of the On-Grid solar power system
On-Grid solar power systems are designed to produce power simultaneously and in parallel with the global power grid. One of the main components of On-Grid solar power systems is the electronic power converter, which converts the DC power produced by the solar panels into AC power according to the voltage and frequency of the grid and automatically cuts off the power transmission when it is not needed. .
In general, there is a two-way connection between the solar power systems and the power grid, so that if the DC power produced by the solar power systems is more than the local consumption, the surplus is fed to the national power grid, and at night and when Due to climatic reasons, it is not possible to use sunlight, the electrical load required by the site is provided by the national electricity network.
Also, in the On-Grid solar power system, if the solar power system goes out of service due to repairs, the electricity needed by local consumers will be supplied through the national power grid. An important point that must be observed in these units is that if the national power grid is interrupted for any reason, the solar unit must also stop production unless it is equipped with a battery and can store its surplus electricity.
Types of On-Grid solar power system
In some cases, to increase the reliability of On-Grid solar power system, energy storage systems which are mainly batteries are used. Therefore, On-Grid solar power system can be divided into the following two groups: With storage system and without storage system
On-Grid solar power system equipped with storage system
On-Grid solar power systems equipped with a storage system are especially suitable for residential houses and small commercial places, because in these systems, the stored energy is used for sensitive loads: refrigerators, lighting, elevators, water pumps, etc. is used
In normal conditions, when the national grid has electricity, the solar power system produces energy to charge the battery and feed the local load, and if there is an excess of production, it injects power into the national grid, and in case of a shortage of production, it takes the required power from It receives the national network. In any case, the battery or other energy storage devices are fully charged.
In On-Grid solar power systems with a battery, the electronic power converter is fed by the solar panel, the output of which is connected to the battery as a local load and sensitive load energy storage. The relationship between the main grid and the interface of the solar unit (main panel) is two-way in terms of power flow, as explained, the lack and excess of power is compensated in this way. Also, the power exchange relationship between the interface of the solar unit and the electronic power converter of the solar unit is also two-way, because if the national grid is energized, the battery must be fully charged, but in this case, the solar unit may not have any production for any reason.
Therefore, you can get help from the main network to charge the battery. For example, on rainy days when the power output of the solar unit is low or zero, the power grid is used to charge the battery. When the power grid is energized, the electronic power converter charges the battery, and when the grid is out of power, the converter uses the battery as an energy source.