Enerize Corp. has developed a new design for photovoltaic (PV) modules using a proprietary transparent polymer material that reportedly outperforms the glass conventionally used as a protective covering. The proprietary polymer material is highly transparent and stable under UV and ionizing radiation exposure.
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 multilayered structure that is more expensive and complicated to manufacture as compared to the new polymer-coated design.
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 multilayer 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.
Compared to PV modules laminated with glass, those coated with Enerize polymer coating materials reportedly exhibit an increase in efficiency of 25% or more. For example, 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%.
This increased efficiency is due to several important features, including better use of light in the shorter (UV) wavelength range of the spectrum, the 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 compared to glass, and the elimination of the interior surface interface, both result in reduced photon loss through reflection.
Additional advantages include reduced weight, increased resistance to degradation by UV and ionizing radiation (so-called photon degradation) and high mechanical strength. These polymer-coated PV modules are stable under prolonged exposure to high and low temperatures, thermal-cycling, mechanical impact, and high relative humidity. Evaluation of the new polymer encapsulation materials has been carried out using PV modules that include up to five solar cells with a surface area of 72 cm2each.
For more information, visitwww.enerize.com.
Polymer Coating Boosts PV Efficiency - Posted 6/3/08
June 3, 2008