The reasons are:
1. Solar panels mainly absorb photons near the green wavelength in visible light. If the solar panel is blue, it means that it reflects blue. wavelength of light.
2. PECVD is a necessary step in the cell production process. The purpose is to coat the surface of the silicon wafer with an anti-reflective film (silicon nitride) to reduce light reflection. The thickness of the coating is about 80um. , due to the optical properties of the silicon nitride film, its surface appears blue.