01

At present, energy storage inverters on the market are divided into two categories according to battery voltage. One type is connected to a battery with a rated voltage of 48V, and the battery voltage range is generally 40-60V, which can be called an energy storage inverter connected to a low-voltage battery. There is also a type of energy storage inverter connected to a high-voltage battery. The battery voltage range of this type of inverter is generally not fixed, and most of them are connected to batteries above 200V.

02

maximum PV input power indicates the maximum power that the PV part of the inverter can accept, but this power is not the maximum power that the inverter can handle. For example, for a 10kW inverter, the maximum PV input power is 20kW, but the maximum AC output of the inverter is only 10kW. If a 20kW PV module is connected, there will generally be a 10kW power loss.

Analysis: Taking the Shencai energy storage inverter as an example, it can store 50% of the photovoltaic energy in the battery while outputting 100% AC. As shown in the figure below, a 10kW energy storage inverter can store 5kW of photovoltaic energy in the battery while outputting 10kW AC, but if a 20kW component is connected, 5kW of photovoltaic energy will still be wasted. When choosing an inverter, in addition to considering the maximum photovoltaic input power, you must also consider the power that the inverter can actually handle at the same time.

03

For energy storage inverters, the AC end is generally divided into a grid-connected output port and an off-grid output port .

Analysis: Grid-connected output ports generally do not have overload capacity. This is because when grid-connected output is used, there is a power grid as support, and there will be no situation where the load cannot be driven. Therefore, the grid-connected output port is not required to have overload capacity.

The off-grid output port is generally not supported by the grid when working, which requires the energy storage inverter to have a short-term overload capacity to drive high-power loads. As shown in the figure below, the rated off-grid output power of the 8kW energy storage inverter is 8KVA, and the maximum output apparent power can reach 16KVA, which can be maintained for 10 seconds. This 10-second time is sufficient for the inrush current of most loads at the moment of startup.

04

4.1 Communication with the battery

4.2 Communication with the monitoring platform

The communication between the energy storage inverter and the monitoring platform is basically the same as that of the grid-connected inverter, and you can choose 4G or Wi-Fi.

4.3 Communication with EMS (Energy Management System)

The communication between the energy storage system and the EMS is generally wired RS485 and standard modbus communication. The modbus protocol of each inverter manufacturer will be different. If you need to be compatible with the EMS, you can communicate with the manufacturer before selecting the inverter to obtain the modbus protocol point table. .