Product Briefing Outline: Enerize Corporation has developed a new design for photovoltaic (PV) modules using a proprietary transparent polymer material that is claimed to outperform glass conventionally used as a protective covering. The proprietary polymer material is highly transparent, and stable under UV and ionizing radiation exposure. The new highly transparent polymer material can be applied directly to the PV module surface at low temperatures, eliminating the need for the adhesives required with glass and some other polymers. Evaluation of the new Enerize polymer encapsulation materials has been carried out using PV modules that include up to 5 solar cells with a surface area of 72 cm2 each.
Problem: Conventional glass has several disadvantages as a protective covering for photovoltaic modules. Glass is relatively heavy, brittle and reflective. Light reflected from the glass surfaces (both exterior and interior) does not reach the solar cell underneath, and glass tends to block ultraviolet light, thus reducing the energy that can be obtained from this part of the spectrum. PV modules that use glass comprise a multi-layered structure that is more expensive and complicated to manufacture as compared to the new polymer coated design.
Solution: In conventional designs using glass, the efficiency of the PV module can be decreased by 7% or more as compared with a PV module without a glass covering, according to Enerize. When PV modules are coated with its polymer encapsulation and protective coating materials the conversion efficiency is increased as compared with the same PV module having no covering. Compared to PV modules laminated with glass, those coated with Enerize polymer coating materials exhibit an increase in efficiency of as much as 25% or more. For example, as compared to a PV module laminated with glass having an efficiency of 16.45%, a PV module with the same type of solar cells coated with Enerize polymer material has an efficiency of 21.2%, according to the company. This increased efficiency is due to better utilization of light in the shorter (UV) wavelength range of the spectrum, high transparency of the polymeric coating in the UV range compared to that of glass, and the capability to be formed with a relief or “crinkle coat” surface morphology. This surface morphology more efficiently captures photons over a wider angle of incidence. The polymer’s low reflectance as compared to glass, and the elimination of the interior surface interface, both result in reduced photon loss through reflection.
Applications: Enerize transparent polymer materials and coating technologies can be used to improve conversion efficiencies and overall performance of mono-crystalline, multi-crystalline, amorphous silicon photovoltaic and non-silicon based PV modules such as CIGS (copper indium gallium selenide).
Platform: The new highly transparent polymer material can be applied directly to the PV module surface at low temperatures, eliminating the need for the adhesives required with glass and some other polymers. This eliminates the multi-layer structure including the reflective surfaces present with glass. No glass is used with this polymer coating. The polymer can be formed as a flat smooth surface or as a “crinkle coat”. The “crinkle coat” version further enhances photon collection efficiency due to the light concentrating effect of the polymer material and its surface morphology.
Availability: May 2008 onwards.