Research on charging control for battery in photovoltaic system

In the existing photovoltaic power generating system, life-span of the storage battery cannot be attained very well, which is a constraint on further development of photovoltaic industry. Aiming at the characteristics of the battery and photovoltaic module in charging system, one type of intelligent photovoltaic charging control strategy and system based on the chip of PIC16F877A is presented and designed. Three-stage charging method is used to maintain the battery in this system. Constant current charging course is carried out combined with Maximum Power Point Tracing (MPPT) function of photovoltaic module. In the stage of constant voltage charging and float charging, PI control method is used to realize constant voltage charging and little constant current charging, and the charging voltage can be compensated by temperature sampling. Experimental results show that the three-stage charging method has been well performed based on the control method mentioned above. The charging time is shortened, and the accuracy in constant voltage charging and float-charge is improved so that the life-span of the storage battery is prolonged.