The use of antireflective coatings on glass-faced solar modules is relatively low in the photovoltaic (PV) industry today. But just as interference-based lens coatings invented by the Carl Zeiss optics company in the mid-1930s revolutionized photography, it is widely expected that coated panel glass will become an industry standard over the next few years.
To that end, Honeywell Electronics Materials recently introduced its new SOLARC antireflective coating material. The company claims it can improve power output of a solar panel by as much as 4 percent. The transparent liquid coating can be factory-applied on new glass or sprayed or rolled on installed PV modules.
In theory, the coating improves photon transmission through the glass, so more of them hit the PV cell, resulting in higher direct current output. The power gain claim is based on the fact that most commercially available panels lose approximately 4 percent of their power output due to light reflection off the surface of the glass. By reducing glare, the antireflective coating improves power efficiency and blends better into the environment.
In tests, SOLARC demonstrated a 4 percent increase in transmission at 550 nanometers and a good response across a broad spectrum relevant for PV cell operation, from 350 nanometers through 1,100 nanometers. In other tests designed to imitate the harsh environments that a panel is exposed to during its lifetime, the coating proved durable and provided additional protection for glass, particularly in hot and humid conditions that may cause glass deterioration.
Dirt buildup on solar glass blocks sunlight. Washing off panels maintains peak efficiency. The California Energy Commission estimated that, on average, panels lose 7 percent of power output because of particulate contamination. According to Honeywell, SOLARC has been optimized to help prevent soiling and dust accumulation.
SOLARC is being made at the company’s Sunnyvale, Calif., plant, which also produces materials for the semiconductor industry. It is being sold to solar-glass manufacturers worldwide and will soon be available to contractors.