1. The covering on the sunny side of a photovoltaic (PV) module, providing protection for the PV materials from impact and environmental degradation while allowing maximum transmission of the appropriate wavelengths of the solar spectrum.
2. The term superstrate refers to a solar cell configuration where the glass substrate is not only used as supporting structure but also as window for the illumination and as part of the encapsulation. During operation the glass is "above" the actual solar cell. Thus the name "Super"strate.
Configuration of thin-film photovoltaic cells
https://energy.gov/eere/sunshot/solar-energy-glossary (1.); http://www.superstrate.net/pv/superstrate.html (2.)
Author: Thomas D.