Why the PV glass must be one side AR coated glass?

In solar module manufacturing, we constantly chase every fraction of a percent in efficiency. But one design rule remains absolute: PV glass is strictly coated on a single side.

Why not double-side coat it to squeeze out more power? It isn't a manufacturing limitation. It's a deliberate choice based on how materials interact.

When a PV module is laminated, the glass is thermally fused directly to the solar cells using an EVA encapsulant. This layout changes the optics completely:

The Outer Surface (Air-to-Glass): Moving from air to glass causes an automatic 4% reflection loss. We apply an Anti-Reflective (AR) coating here to bridge the gap, cutting that loss down to about 1%.

The Inner Surface (Glass-to-EVA): The refractive index of EVA is almost identical to glass. When laminated, they "optically match" naturally. Interface reflection drops below 0.1% on its own.

Adding a chemical coating to the inner side provides zero optical benefit. Even worse, it disrupts the mechanical bond between the glass and EVA. This severely increases the long-term risk of delamination and moisture ingress in the field.

In PV manufacturing, single-side AR coating is the perfect balance between peak optics and 25-year reliability.