Front Cover Glass Research Articles

Crystalline Si photovoltaic modules based on TiO2-coated cover glass against potential-induced degradation

Potential-induced degradation (PID) in multicrystalline Si photovoltaic (PV) modules was generated by applying −1000 V from an Al plate attached on the cover glass of the module to the Si cell at 85 °C. The solar energy-to-electricity conversion efficiency of the standard Si PV module remarkably decreased from 15.9% to 0.6% after 2 h of the PID test. Increased concentration of Na species on the surface of the Si cell after the PID test was observed by secondary ion mass spectrometry (SIMS) measurement. Our results indicate that high minus voltage stress toward the Si cell causes the diffusion of metal cations, such as Na+, from the front cover glass toward the Si cell, resulting in remarkable decrease in PV performance. PID was significantly prevented by a coating of TiO2-thin film on the cover glass that suppressed the diffusion of Na+, demonstrating an attractive and promising technique for producing low-cost PID-resistant PV modules.

Non-Glare Headlight with a Sodium Nitrate Polarizer as a Filter

With a view of obtaining a polarization headlight which is sufficiently bright for a free field driving and at the same time is dim to a driver of an oncoming vehicle who views the headlight through an analyser placed in the crossed position to the polarizer over this headlight, a set of polarization headlight system is constructed. It consists of a sealed beam headlamp with a smooth front cover glass, having the same 50 watt filament as the conventional sealed beam one, a cylindrical lens system over a part of the aperture and a sodium nitrate polarization plate. Illuminance of this set satisfies the Japanese Industrial Standard (JIS), which is equivalent to the SAE in America. Its maximum light intensity, 26200 Cd, is about 2.7 times as high as that of the known type of polarization headlight (9800 Cd) with the use of “Dichrom” or “Polaroid”, and is about 86 per cent of 30600 Cd of the conventional sealed beam headlight.