Classification of Solar Photovoltaic Glass

Photovoltaic glass substrates used for solar cells generally include ultra-thin glass, surface-coated glass, low-iron content (ultra-white) glass and other types.

Photovoltaic glass can be divided into 3 types of products based on the nature of use and manufacturing methods. One of them is the cover of flat-panel solar cells, which is usually rolled glass. The other is to coat the surface of flat glass with a thin film battery conductive substrate made of semiconductor material that is usually only a few microns thick. The last type is lens or reflector glass used in concentrating photovoltaic systems. The characteristics and functions of these three products are completely different, and their added value is also very different.

The most widely used solar photovoltaic glass today is high transmittance glass, which is a glass with low iron content, which is commonly known as ultra-white glass. Iron is an impurity in ordinary glass, except for heat-absorbing glass. The presence of iron impurities, on the one hand, colors the glass, and on the other hand, increases the heat absorption rate of the glass, which also reduces the light transmittance of the glass.

Iron in glass is introduced by the raw materials themselves, refractory materials or metal production equipment, etc., and cannot be completely avoided. The iron content in glass can only be reduced as much as possible through production control. At present, the iron content of solar cell glass is between 0.008% and 0.02%, while the iron content of ordinary float glass is more than 0.7%. Low iron content impurities result in high solar transmittance. As for the most widely used 3.2mm thick and 4mm thick glass, the visible light transmittance of sunlight generally reaches 90%~92%.

As one of the most important materials for solar devices, solar photovoltaic glass requires that the glass must be highly transparent. Therefore, the requirements for the iron content in the siliceous raw materials used to produce solar glass are very strict, and the Fe₂O₃ content is generally 140 to 150ppm.