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What is the independent photovoltaic energy storage system
- Aug 02, 2018 -

Photovoltaic power generation system can be divided into grid connected photovoltaic power generation system and independent photovoltaic power generation system according to whether grid connected. Independent photovoltaic power generation system mainly refers to a variety of photovoltaic power generation systems operating independently of the grid, such as solar street lamps, rural household photovoltaic power supply.


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Independent photovoltaic energy storage system

Compared with grid-connected photovoltaic  system, independent photovoltaic  system refers to a photovoltaic system that operates independently without access to the power grid. Has been widely applied at present and self-contained systems such as solar street lamp, solar mobile power supply, the photovoltaic power output and load are not at the same time, given the photovoltaic output does not always meet the load demand, therefore in the independent photovoltaic power generation system configuration energy storage system is effectively promote photovoltaic  power output, the effective measure to enhance the system stability, energy storage system at the same time also has to provide load starting current, the action of muzzle voltage, etc. Currently, the widely used independent photovoltaic  system consists of photovoltaic power generation, control/inverter and energy storage.

At present, batteries are commonly used as energy storage devices in independent photovoltaic systems which have been commercialized and applied. Photovoltaic components and control/the life of the inverter are can reach more than ten years, but the service life of the battery in 6 ~ 7 years alone, at the same time the cost of the battery can account for more than 25% of the whole system, so the energy storage in the independent photovoltaic system configuration and control objectives to extend battery life as much as possible, reduce the system cost. Under this premise, the primary goal of energy storage capacity and power allocation in an independent photovoltaic system is to optimize the battery life of charging and discharging. The capacity of energy storage units in independent photovoltaic  systems is usually small, and independent control systems and control strategies are not normally configured. Energy storage and photovoltaic modules are controlled by the same control system. At present, the most widely studied and applied maximum power point tracking (MPPT) control system is aimed at optimizing the output of photovoltaic modules and lacks the optimal control of energy storage system. With the increasing efficiency of photovoltaic modules and the decreasing price, the energy storage cost remains high. Therefore, the development of energy storage priority control strategy and control system in independent photovoltaic system has a broad prospect.