Takeharu Yamawaki

Thermal recovery effect on light-induced degradation of amorphous silicon solar module under the sunlight

Abstract The thermal recovery effect from the light-induced degradation under the sunlight is experimentally investigated on the amorphous silicon photovoltaic module (a-Si PV module) for installing directly to the roof flames of wooden houses. To enhance the recovery effect, the heat-insulating material is attached to the back side of the module for increasing the module temperature under the sunlight: the heat-insulated module. The generated power from the heat-insulated module is compared with that from the normal module (without the heat-insulating material) for 2 yr, and it has been cleared that the generated power normalized at 25°C from the heat-insulated module is approximately 7.3% higher than that from the normal one with the average temperature increase of 4.2°C under the sunlight.

Development of photovoltaic modules integrated with roofing materials (heat insulated roof panel)

The authors have started to develop low cost photovoltaic modules integrated with roofing materials for wooden houses. They made a concept of the design for the modules using amorphous silicon solar cells and produced test modules that consist of untempered surface glass, solar cells, waterproof sheet, heat insulating materials and base frames. They have primarily tested the distributed pressure resistance as a building component. When applying a load from the front surface side of the modules, a 3.6 mm deflection at the center of the specimen under 300 kg/m/sup 2/ load was observed, which is equivalent to a snowfall of 1.2 meters. As a result, they have finally confirmed that modules have enough structural strength to be used as a roof panel. They also tested the impact resistance of untempered surface glass by the testing method stated in J1S3212. In this test, cracks could not be seen from a height of 75 cm.