Product Briefing Outline: XeroCoat Technology has entered the solar energy market targeting the solar thermal and solar photovoltaic segments with its anti-reflective coatings. The XeroCoat anti-reflective coatings are claimed to increase conversion efficiency and, consequently, the power output of solar systems, while being of low cost. The combination of a single-layer optical coating and graded low refractive index enables XeroCoat’s anti-reflective coating to achieve the highest attainable optical performance for any type of solar cover glass, the company claims. XeroCoat is actively engaged in demonstrating the technology to several leading photovoltaic module and solar thermal system manufacturers.
Problem: Photovoltaic modules suffer from reduced conversion efficiency even before the sun’s light reaches the solar cells. This is because the solar module’s protective cover glass reflects some of the incident light. For typical glass panels, depending on the time of day, 4% to 15% and more of the incoming light is lost from reflections and, thus, is not available to generate electricity. Applying an anti-reflective coating to the cover glass of the module will reduce these reflections and increase the module’s output power. Today, anti-reflective coatings for the solar module cover glass are used in less than 5% of photovoltaic solar systems. Current commercial PV technologies convert 10%-20% of the incoming light to electricity. The same module with a suitable anti-reflective coating can deliver an additional 0.3%-0.6% power conversion. A product achieving higher conversion efficiency in a cost-effective manner can make solar modules more affordable. Delivering high performance requires that the anti-reflective coating reduces reflections and maximizes the solar energy available for conversion into electricity across the broadest range of wavelengths and angles possible. While multi-layer coatings were the traditional solution, they add cost and reflect sunlight more than uncoated glass at certain incident angles.
Solution: By using the XeroCoat anti-reflective coating on a photovoltaic module, the solar energy reaching the solar cells is claimed to increase by as much as 3% at noon and by as much as 6% at early morning and evening hours. Module makers can expect a 3% increase in power output on a peak watt (Wp) basis, and a 4% increase in energy produced on a kilowatt-hour (kWh) basis, resulting in the equivalent of a solar cell efficiency gain of approximately 0.5-0.75% points, without modification. For solar system owners, XeroCoat’s anti-reflective coating increases the energy output per module, which translates to higher revenue, especially in locations with a feed-in tariff. In addition, because the peak watt per module is higher, fewer modules are needed to achieve the same total solar system watt rating, resulting in balance of system’s cost savings.
Applications: Applicable across all solar energy technologies including crystalline, thin-film and concentrating solar thermal.
Platform: Uses non-toxic, recyclable coating materials and a low-energy manufacturing process. Meets IEC 61215 module test standards and exceeds current industry standards for abrasion resistance.
Availability: July 2008 onwards.