When many people are going to install a photovoltaic power station on their roofs, they will always have a problem: Is it grid-connected or off-grid, do you need a battery? Today, Xiaobian will tell you the difference between the two.
In simple terms:
The off-grid photovoltaic power station stores solar power generation into a battery and then converts it into a household 220V/380V voltage through an inverter.
The grid-connected photovoltaic power station can also be understood from the name. It refers to the connection with the mains. The grid-connected photovoltaic power station has no electrical energy storage device, which is directly converted into the voltage requirements of the national grid through the inverter, and is preferentially for the family. Use, household electricity can be sold to the country.
At present, national policy support is supporting solar photovoltaic power generation. Household photovoltaic power plants will have state subsidies as long as they generate electricity. However, if you are connected to the network, you must first apply with the local national grid department.
Grid-connected photovoltaic power station
On-grid, it is necessary to connect 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. The solar panels are directly converted into 220V/380V AC by the inverter and supply power to the household appliances. When the amount of solar energy generated exceeds the amount of electricity used by household appliances, the excess electricity is delivered. When it comes to the public power grid, when the amount of solar energy is not enough for household appliances, it is automatically replenished from the grid. And the whole process is intelligently controlled and does not require manual operation.
Since this photovoltaic power generation system does not require the use of a battery, it also saves a lot of cost. In particular, the country's new grid-connected policy has clearly stated that household PV power plants can be connected to the grid free of charge, and excess electricity can be sold to power companies. From the long-term perspective of investment, according to the 25-year life expectancy of household PV power plants, the cost can be recovered in about 5 years, and the remaining 20 years are earned. Therefore, if you want to save electricity costs and the power supply is convenient, then choose the grid-connected solar power system, which is the current mainstream way.
Off-grid photovoltaic power station
This is also called an independent photovoltaic power station. It is a power generation system that operates independently without relying on the power grid. It mainly consists of solar panels, energy storage batteries, charge and discharge controllers, inverters and other components. The electricity generated by the solar panel directly flows into the battery and is stored. When the appliance needs to be powered, the DC current in the battery is converted into 220V AC by the inverter, which is a repeated cycle of charging and discharging. This kind of power generation system is widely used because it is not restricted by the area. It can be installed and used as long as it is exposed to sunlight. Therefore, it is suitable for remote and non-grid areas, isolated islands, fishing boats, outdoor breeding bases, etc., and can also be used as a frequent power outage. Emergency power generation equipment in the area.
Such a system has to be equipped with a battery and 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 increases the cost of use. In terms of economy, it is difficult to get a wide range of promotion and use, so it is not suitable for use in places where electricity is convenient.
However, it is very practical for families in areas without power grids or in areas with frequent power outages. In particular, in order to solve the lighting problem during power failure, DC energy-saving lamps can be used, which is very practical. Therefore, off-grid power generation systems are specifically designed for use in areas without power grids or in areas with frequent power outages.