A primary goal of Photovoltaics is to generate electricity while reducing reliance on the world's petroleum supply. However, PV backsheets are produced from petro-based chemicals, which, to a certain extent, defeat the purpose of using solar energy. Materials from three sustainable resources were targeted for PV backsheet development: PLA made from corn, a cellulosic made from cotton, and a type of nylon made from castor beans. Some of these films were coated with various materials to lower the WVTR. Modules produced using these backsheets were subjected to rigorous testing, including the damp heat test and the wet Hypot test as outlined in UL 1703. As cast PLA film tends to be very brittle. This problem is solved with additives or biaxial orientation. PLA film is UV stable and highly transparent which would merit it for consideration as a front glazing as well as for a backsheet. However, its moisture resistance is not robust. A cellulosic film made from cotton was considered which has a continuous duty temperature rating of 105°C. This product had to be modified significantly to convert it from a hydrophilic film to a hydrophobic one. Additionally, this material has an RTI value of 90°C. Nylon 11, produced from castor beans, is very interesting because it is bio-sustainable, but not biodegradable. It has improved moisture properties over the more common nylons, and has an RTI value of 105°C.

Date Published: 10 September 2008
PDF: 10 pages
Proc. SPIE 7048, Reliability of Photovoltaic Cells, Modules, Components, and Systems, 70480C (10 September 2008); doi: 10.1117/12.792646

Published in SPIE Proceedings Vol. 7048:
Reliability of Photovoltaic Cells, Modules, Components, and Systems
Neelkanth G. Dhere, Editor(s)