To reduce photovoltaic (PV) power generation costs, the reduction of PV module manufacturing costs, the improvement of cell and module efficiencies, and the long-term output power warranty of PV modules are necessary. Using the high-quality, low-cost crystal growth technology, we developed a high-quality casting process by the seed-cast method. Using a seed-cast wafer, an efficiency of 20.54% has been obtained with passivated emitter and rear cells (PERCs). The ohmic contact degradation of front electrodes and potential-induced degradation are the typical modes that significantly affect the module lifetime. Considering the field stresses induced by ultraviolet light, heat and humidity (H&H), and the electrical potential difference, sequentially combined stress tests of small modules and additional stress tests of field-aged modules are performed. The test results for the modules fabricated using our technology indicated that the modules have a sufficiently long lifetime of more than 30 years and are potential-induced degradation (PID)-free under these stresses in Japanese domestic environments.

This paper describes the development of an industrial processing sequence that employs the screen printing and firing for large area mufticrystalline silicon (mc-Si) solar cells. A record high efficiency mc-Si solar cell of 17.7%. cell area: 232.5cm2. has been .achieved using Kyocera's original cast mc-Si material.The diffusion length of mc-Si material w3s improved after cell processing especially at the region that had low diffusion length by getterjng or passivation effects. The diffusion length after cell processing was about 270 pm, and this value corresponds to the value estimated internal quantum efficiency curve of P G I D simulation very well.The photovoltaic module has been fabricated using 48 cells that have average efficiency of 17.2% with this type of cell. The record module efficiency of 15.7% h3s been achieved.

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