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Difference between grid-connected generation system and off-grid generation system in solar photovoltaic system

author:admin   add time:2019-03-06 15:47:52   browse: < Back To News

Today, to give you a science popularization, if you install solar photovoltaic power plants in your home, is it connected to or off the grid, do you need batteries?
Simply put, off-grid photovoltaic power plants store solar power into storage batteries, and then convert it into 220V voltage for household use through inverters. Grid-connected power plants can also be roughly understood from the name, which refers to the connection with municipal electricity. Grid-connected photovoltaic power plants do not have energy storage devices, directly converted into the voltage requirements of the national grid through inverters, and give priority to household use, household electricity can be sold to the state. At present, the national policy support is vigorously supporting solar photovoltaic power generation. As long as domestic photovoltaic power plants generate electricity, there will be state subsidies. However, if it is connected to the grid, it must first apply with the local State Grid Department.
First, grid-connected photovoltaic power plants
Connecting to the 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 connected together. This is a power generation system that must rely on the existing power grid to operate. It is mainly composed of solar panels and inverters. Solar panels emit electricity directly converted into 220V AC by inverters and supply power to household appliances. When the amount of solar energy exceeds the amount of electricity used by household appliances, the surplus electricity is transferred to the public grid; and when the amount of solar energy can not meet the needs of household appliances, it is automatically supplemented from the grid. And the whole process is intelligent control, without manual operation.
Because this photovoltaic power generation system does not need to use batteries, it will greatly save costs. In particular, the new policy of networking that has been issued by the state has clearly indicated that home photovoltaic power plants can be accessed free of charge, and surplus electricity can also be sold to power companies. From the long-term perspective of investment, according to the 25-year service life of home photovoltaic power plants, the cost can be recovered in about 6-10 years, and the remaining 10 years will be earned. Therefore, if you want to save electricity costs and convenient power supply, choose grid-connected solar power generation system, which is the mainstream way at present. In this Wechat Public Number (Home Photovoltaic Power Generation), there are more detailed descriptions of costs and benefits.
However, grid-connected has its drawbacks, that is, when the public grid is cut off, photovoltaic power generation can not operate. But if the grid-connected inverters are replaced by intelligent micro-grid inverters (grid-connected and off-grid hybrid inverters), the power station can operate normally.
So, how can we store the electricity generated during the day and use it at night? This requires adding controllers and batteries. During the day, the controller stores the photovoltaic power in the batteries. At night, the controller releases the power stored in the batteries for lighting.
Second, off-grid power stations
This is also known as an independent photovoltaic power station, which is independent of the power grid and operates independently. It mainly consists of solar panels, storage batteries, charge and discharge controllers, inverters and other components. When the power generated by solar panels is directly flowed into the battery and stored, the DC current in the battery is converted into 220V AC current by an inverter, which is a process of repeated cycle charging and discharging. This kind of power generation system is widely used because it is not restricted by the region. It can be installed and used as long as there is sunshine. Therefore, it is very suitable for remote areas without power grid, isolated islands, fishing boats, outdoor breeding bases and so on. It can also be used as emergency power generation equipment in areas with frequent power outages. This system has to be equipped with batteries, and occupies 30-50% of the cost of power generation system. Moreover, the service life of the battery is generally 3-5 years, and it will be replaced later, which increases the cost of use. Economically speaking, it is difficult to be widely used, so it is not suitable for use in places where electricity is convenient.
However, it has strong practicability for families in areas without power grid or with frequent blackouts. Especially in order to solve the lighting problem of power outage, DC energy-saving lamp can be used, which is very practical. Therefore, off-grid power generation system is specially designed for non-grid areas or areas where power outages are frequent.
Simply put: grid connection does not require batteries, off-grid storage batteries.

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