In simple terms, an off-grid photovoltaic power station stores solar power in a battery, and then converts it into a household 220v voltage through an inverter. The grid-Tied power station can also be roughly understood from the name. It refers to the connection with the city electricity. The grid-Tied photovoltaic power station has no electric energy storage device, and directly converts it into the voltage required by the national grid through the inverter, and gives priority to the family use, Unused electricity for households can be sold to the state.
1.Grid-Tied photovoltaic power station
Grid-Tied means that it must be connected to the public grid, solar power generation, home grids, and public grids are linked together. This is a power generation system that must rely on the existing grid to operate. It is mainly composed of solar panels and inverters. The output of solar panels is directly converted into 220V AC power by the inverter and supplies power to household appliances. When the electricity generated by solar energy exceeds the electricity used by household appliances, the excess electricity is sent to the public grid, and when the electricity generated by solar energy cannot meet the usage of household appliances, it is automatically supplemented from the grid. The whole process is intelligently controlled, no manual operation is required
Since this photovoltaic power generation system does not require the use of batteries, the cost is greatly saved. In particular, the policies issued by the governments of many countries indicate that household photovoltaic power stations can be connected to the grid for free, and the excess electricity can also be sold to power companies. From the long-term perspective of investment, according to the 25-year service life of the household photovoltaic power station, the cost can be recovered in about 6 to 10 years, and the remaining ten years can be earned.
However, the grid connection also has the disadvantage that when the public grid is cut off, the photovoltaic power generation cannot be operated. However, if the grid-Tied inverters are replaced with smart micro-grid inverters (on-grid and off-grid hybrid inverters), the power station can operate normally.
So, how can the electricity generated during the day be stored and used at night? This requires adding a controller and a battery. During the day, the controller stores the electricity generated by photovoltaics in the battery, and at night, the controller releases the electricity stored in the battery for lighting.
2.Off-grid photovoltaic power station
An off-grid photovoltaic power station, also known as an independent photovoltaic power station, is a power generation system that operates independently without relying on the power grid. It is mainly composed of solar panels, energy storage batteries, charge and discharge controllers, inverters and other components. The electricity emitted by the solar panel directly flows into the battery and is stored. When it is necessary to supply power to the electrical appliance, the DC power in the battery is converted into 220V AC power by the inverter, which is a repetitive cycle of charge and discharge. This kind of power generation system is widely used because it is not restricted by regions. It can be installed and used as long as there is sunlight. Therefore, it is very suitable for remote areas without power grids, such as isolated islands, fishing boats, outdoor breeding bases, etc. , can also be used as emergency power generation equipment in areas with frequent power outages.
This kind of system must be equipped with a battery, and it occupies 30% to 50% of the cost of the power generation system. Moreover, the service life of the battery is generally 7 to 10 years, and it has to be replaced after that, which increases the cost of use. From an economical point of view, it is difficult to get a large-scale promotion and use, because it is not suitable for use in places where electricity is convenient.
But for families in areas without power grids or areas with frequent power outages, it has strong practicability. Especially in order to solve the lighting problem during a power outage, DC energy-saving lamps can be used, which is very practical. Therefore, off-grid power generation systems are specially designed for use in areas without power grids or areas with frequent power outages.
