Japanese researchers have developed a repair technique for solar modules with damaged power rails and solder strips. They claim that the new method can be implemented on site without removing the panels from the array.
“If the power rails and solder strips of the silicon solar modules are removed, it is possible to repair the defective part on site,” said Yu Kawano, lead author of the study. pv magazine. “We have developed a low-cost technology to extend the life of solar cells, allowing them to restore their power directly at the outdoor installation site without disassembling the solar module or removing it from the solar panel.”
The new method utilizes a portable induction heating system developed by Japanese technology supplier Toray Engineering Co., Ltd.. “It has a spot diameter of 2.0 mm and operates at a power of 3.5 kW, a frequency of 900 kHz and a distance between the system and the PV module of 2.0 mm,” the researchers explained.
The team tested the induction heating system by applying it only to the region where the switching failures of the damaged modules were in the heating time range of 0.1 s to 10.0 s, and said that a heating time exceeding the 10.0 s threshold could cause further damage. for panels.
For testing, the researchers used damaged and undamaged modules with a backplate/EVA/Si solar cells/EVA/cover glass structure measuring 145 mm × 145 mm and series-connected solar cells measuring 26 mm × 120 mm.
“According to the result, the optimized heating time of 2.0 seconds leads to more uniform light throughout the module with lines of high electroluminescence (EL) intensity in both horizontal and vertical lines,” they elaborated. “An excessively long 10.0 second warm-up time reduces the fill factor (FF) value to 0.765.”
The researchers said the system proved effective in reducing series resistance and restoring the performance of damaged panels.
“Notably, a more pronounced recovery of performance can be seen using this proposed repair method in a silicon electronic module with many solder-to-electrode, solder-to-bonding bond defects,” they noted. “Optimized heating time of the detached Si PV module results in a recovery of the FF value close to that of the standard Si PV module, which is consistent with the recovery of EL imaging.”
The new technique is described in the study “Development of a repair technique for interconnecting silicon photovoltaic modules with an induction heating system, was published Solar energy. The research team includes researchers from Ritsumeikan University and the Japanese copper wire manufacturer Showa Seisakusho Co., Ltd.