With increasing in the capacity of solar photovoltaic power plants,  there are newly installed photovoltaics not allowed to be sent to the grid in many palce due to consumption reasons. When the photovoltaic power is greater than the load power, the more part can only be wasted, which will reduce the income of the power station. If the time is longer and the wasted power is greater, there may be no investment value. it is necessary to Installing anti-backflow and solar energy storage devices can reduce the power loss of anti-backflow, and can be used as a backup power supply for the load, which is more economical than a simple grid-connected anti-backflow system.

The solar backflow prevention device is to install a current sensor at the grid connection point. When it detects that there is current flowing to the grid, the photovoltaic output power remains unchanged, and the bidirectional converter is activated to store the excess electrical energy in the battery. Wait for the photovoltaic power to decrease or Release when the load power increases. From the cost point of view, to install a set of anti-backflow system, it is necessary to add energy storage equipment, including energy storage converters and batteries. The price is about $320/kWh, and the cost is about $0.078 per kWh. The cost is still relatively high. , So when designing an energy storage system, pay attention to the following three points:

Firstly is to track the photovoltaic power generation curve, the load’s power curve, and calculate the energy storage configuration; the second is to select the technical solution of energy storage. From the cost point of view, the AC coupling design is flexible and more suitable for anti-backflow energy storage; the third is to Choose the anti-backflow detection point to install the current sensor. If the selection is improper, a lot of power may be wasted.

In a small solar home system below 30kW, if the proportion of photovoltaic self-use is more than 80%, the excess electricity is not too much, the total daily kWh is below 15 degrees, or the daily electricity bill is below $3; the electricity price is less than $0.078, which is close to the installation of energy storage. Electricity cost, it is recommended to configure an anti-reverse flow device, which is low cost, safe and reliable; if the excess photovoltaic capacity is greater than 20%, or the excess photovoltaic power is greater than 30kW, the daily electricity exceeds 100 kWh, and the electricity price is higher than 0.5 yuan, it is recommended to configure storage can.