Photovoltaic power generation system is a power generation system that converts solar energy into electric energy. In the global trend of reducing carbon emissions, photovoltaic power generation, with the characteristics of easy access to resources, rapid decline in cost, flexible installation scale and small environmental restrictions, accounts for an increasing proportion in the energy structure of more developed countries.
1. Design requirements of photovoltaic energy storage lithium battery:
The capacity of photovoltaic energy storage lithium battery is large, which can be used by customers according to different battery capacity requirements; the battery should be able to adapt to various loads, inductive load, capacitive load and resistive load, and the battery should be safe and explosion-proof; and can adapt to long time full power storage. For this reason, our company adopts the imported battery cell, which has the advantages of high energy ratio, light weight, small volume, high cycle life, high safety, high voltage and good consistency. The lithium battery pack adopts the special structure explosion-proof process design, and the specific parameters are as follows:
Nominal voltage: 51.2V
Nominal capacity: 50Ah
Charging voltage: 54.75V
Discharge current: 50A
Instantaneous discharge current: 150A
Discharge cut-off voltage: 41.25V
Product size: 451*415*133mm
Charging temperature: 0 ~ 45 ℃
Discharge temperature: - 20 ~ 60 ℃
Battery shell: cold rolled sheet metal
2. Design scheme of photovoltaic energy storage lithium battery:
1) BMS: it is mainly a protection circuit designed for rechargeable lithium battery pack. Due to the chemical characteristics of lithium battery, it is necessary to provide intelligent power calculation, overcharge, over discharge, short circuit, overcurrent and other protection functions to avoid burning, explosion and other hazards.
2) Protection IC (Protection IC): the main protection function chip of the design scheme, which can monitor the overcharge, over discharge, over current, short circuit and other functions of the cell online and constantly, so that the cell can work in a safe, stable and efficient range.
3) Temperature switch: mainly designed for temperature protection function. When the temperature of the battery itself reaches 70±5 ℃ due to other abnormal problems, the temperature switch will act for temperature protection
4) Lithium ion cell: lithium ternary / lithium iron phosphate.
5) Field effect transistor (MOSFET): MOSFET, in the protection circuit to play a switching role, always make the voltage at both ends of the load will not rise or fall, to ensure voltage stability.
6) Battery packaging: cold rolled sheet metal.