The Difference Between On-grid And Off-grid Solar PV Power System

Views: 10     Author: Site Editor     Publish Time: 2021-07-07      Origin: Site


The Difference Between On-grid And Off-grid Solar PV Power System

1. On-grid PV power generation system

On-grid means that it must be connected to the public power grid, that is, solar power generation, home power grid, and public power grid are linked together. This is a power generation system that must rely on the existing power grid to operate. It is mainly composed of a solar panel and an inverter. The electricity generated by the solar panel is directly converted into 220V alternating current through the inverter and supplies power to the household appliances. When the power generated by solar energy exceeds the power used by household appliances, the surplus electricity is transmitted to the public grid; when the power generated by solar energy cannot meet the use of household appliances, it is automatically supplemented from the power grid. And this whole process is intelligently controlled and does not require manual operation.

Since this PV power generation system does not need to use batteries, it greatly saves costs. In particular, the country’s new on-grid policy has clearly stated that home PV power stations can be connected to the grid for free, and excess electricity can be sold to power companies. From a long-term perspective of investment, based on the 25-year service life of a household photovoltaic power station, the cost can be recovered in about 6-10 years, and the remaining ten years will be earned. Therefore, if you want to save electricity bills and provide convenient power supply, you can choose a grid-connected solar power system, which is also the current mainstream method.

However, if it is connected to the grid, you must first apply to the local State Grid Department.

Meanwhile, on-grid also has its disadvantages. Even when the public grid is out of power, PV power generation cannot operate. However, if the on-grid inverter is replaced with a smart microgrid inverter (a hybrid inverter for grid-connected and off-grid), the power station can operate normally.

So, how can we store the electricity generated during the day and use it at night? This requires the addition of a controller and a battery. During the day, the controller stores the electricity generated by the photovoltaic in the battery, and at night the controller releases the electricity stored in the battery for lighting.

2. Off-grid PV power station

This is also called an independent PV power station, which is a power generation system that does not rely on the grid and operates independently. It is mainly composed of solar panels, energy storage batteries, charge and discharge controllers, inverters and other components.

The electricity generated by the solar panel flows directly into the battery and is stored. When it is necessary to supply power to the appliance, the DC current in the battery is converted into 220V AC power through the inverter, which is a repeated cycle of charging and discharging.

This kind of power generation system is not restricted by region and is widely used. It can be installed and used as long as there is sunlight. Therefore, it is very suitable for remote areas without power grids, isolated islands, fishing boats, outdoor breeding bases, etc., and can also be used as frequent power outages. Emergency power generation equipment in the region.

This kind of system must be equipped with batteries, and it occupies 30-50% of the cost of the power generation system. Moreover, the service life of the battery is generally 3-5 years, and it has to be replaced afterwards, which adds to the cost of use. In terms of economy, it is difficult to be widely promoted and used, so it is not suitable for use in places where electricity is convenient.

But for households in areas without power grids or areas with frequent power outages, it has strong practicality. Therefore, the off-grid power generation system is specifically designed for use in areas without power grids or in areas with frequent power outages.

If you want to know more about the solar power system, Sunflower Solar will help you.

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