Hot spot effect of photovoltaic modules? What's the harm? Causes and protective measures

author: Source

Hot spot effect: under certain conditions, the shielded solar cell module in the series branch will be used as a load to consume the energy generated by other illuminated solar cell modules, and the shielded solar cell module will heat at this time.

The blocked photovoltaic modules will consume part or all of the energy generated by the illuminated photovoltaic modules, reducing the output power; Serious damage will permanently destroy the solar cell module or even burn the module.

Causes of hot spot effect: 1. The root causes of hot spot effect are the mixing of individual bad batteries, faulty welding of electrode pads, the evolution of batteries from cracks to fragmentation, the deterioration of individual battery characteristics, local shadow shielding of batteries, etc. 2. Due to the existence of local shadow, the current and voltage of some single cells in the solar cell module have changed. As a result, the product of local current and voltage of solar cell modules increases, resulting in local temperature rise on these cell modules.

Protective measures: a bypass diode is connected in parallel between the positive and negative poles of the solar cell module to increase the reliability of the square array. Normally, the bypass diode is under reverse bias voltage, which does not affect the normal operation of the component. Principle: when a battery is blocked, other batteries promote its reverse bias to become a large resistance. At this time, the diode is turned on, and the part of the total battery exceeding the photogenerated current of the blocked battery is shunted by the diode, so as to avoid overheating and damage of the blocked battery. To avoid the energy generated by the lighting component being consumed by the shielded component.