Mechanical damage of half-cell cutting technologies in solar cells and module laminates

Half-cell modules are gaining an increasing market share due to their potential of increasing the module power without requiring any changes in the cell technology. However, it has turned out that different cell separation technologies can yield a similar electrical performance of the half-cells, yet leading to an entirely different mechanical behavior of the cells. Hence, the mechanical strength on solar cell and module laminate level was evaluated for thermal laser separation (TLS) and laser scribing with cleaving (LSC) cutting technologies on multicrystalline silicon Al-BSF solar cells. It could be systematically shown, that mechanical defects which are found on cell level can also be seen on module level. More precisely, the strength for the LSC batch was decreased by 35 % on cell level and 23 % on module level. The TLS process did not change significantly the strength on cell or module laminate level. Additionally, the origin of fracture was found at the edge for the laser batch and on the back side pads for the full cells and TLS cut cells. The electrical evaluation has shown minor electrical power losses of the half-cells leading to an efficiency reduction of less than 1 %rel.