The Research On The Hot Spot Effect For PV Components

With the wide application of PV power generation, The influencing factors of module performance and life have attracted more and more concern, hot spot phenomenon is one of them. When solar cells exist block, broken or other conditions that caused the current appear mismatch, may induce hot spot phenomenon of modules, affect the energy output of the PV system, shorten the service life of PV system, local temperature too high may even cause safety accidents such as fire. Study hot spot phenomenon of modules and its improving method has important significance for the healthy development of solar PV industry.This paper in order to reduce the damage of module by the hot spot phenomenon,combined with solar cells equivalent model, analysis of hot spot phenomenon inherent principle, two important electrical parameters that affect the hot spot phenomenon are parallel resistor of cells and dark current. Analysis of the process and conditions of hot spot phenomenon leads to the bypass diode turn-on, and the process from positively biased to reverse biased of the solar cells when hot spot phenomenon happens. Set up module hot spot phenomenon experimental study system, make hot spot phenomenon output characteristic experiments, test and analysis the relation of aging and the power attenuation of modules and hot spot phenomenon, analysis the power generation of the power plant through the remote monitoring platform, identify hot spot phenomenon occurrence status. come to a conclusion:reverse current of single cell must be controlled below a certain level, so that the bypass diode will turn-on and effectively prevent hot spot phenomenon. Hot spot phenomenon has little effect on output characteristics when happens in the same circuit of modules but has big effect when happens in the different circuit. The aging degree is not the same inside the module result in current mismatch of cells, may occur hot spot phenomenon. Through the remote monitoring platform, analysis of the conditions of power generation and temperature,can know if the hot spot phenomenon happens, realize alarm and emergency handling.