Solar cell modules with improved backsheet

Abstract

Disclosed is a polyamide-ionomer composition suitable for use in a backsheet in a photovoltaic module comprising a polymer component a polyamide and an anhydride ionomer comprising a copolymer of ethylene, an alpha, beta-unsaturated C₃-C₈ carboxylic acid and an ethylenically unsaturated dicarboxylic acid or derivative thereof selected from the group consisting of maleic acid, fumaric acid, itaconic acid, maleic anhydride, and a C₁-C₁ alkyl half ester of maleic acid, wherein the carboxylic acid functionalities present are at least partially neutralized to carboxylate salts of one or more alkali metal, transition metal, or alkaline earth metal cations; 0 to 20 weight % of pigment; and 0 to 40 weight % of filler; preferably wherein the combination of pigment and filler comprises 10 to 50 weight % of the composition; and 0 to 5 weight % of weatherability additives.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application claims priority under 35 U.S.C. §119(e) from U.S. Provisional Patent Application No. 61 / 985,579, filed Apr. 29, 2014, hereby incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]This invention relates to photovoltaic solar cell modules having an improved backsheet.BACKGROUND OF THE INVENTION[0003]A common form of solar cell module or photovoltaic (PV) module is made by interconnecting individually formed and separate solar cells, e.g., crystalline silicon solar cell, and then mechanically supporting and protecting the cells against environmental degradation by integrating the cells into a laminated solar cell module. The laminated modules usually comprise a stiff transparent protective front panel or sheet, and a rear panel or sheet typically called a “backsheet” or “backskin”. Interconnected solar cells and an encapsulant are disposed between the front and back sheets so as to form a sandwich arran...

AI Technical Summary

Problems solved by technology

However, EVA has certain limitations: (1) it decomposes under sunlight, with the result that it discolors and gets progressively darker, and (2) its decomposition releases acetic acid which in turn promotes further degradation, particularly in the presence of oxygen and / or heat.

However, Tedlar® and Tedlar® laminates are not totally impervious to moisture, and as a consequence over time the power output and / or the useful life of modules made with this kind of backsheet material is reduced due to electrical shorting resulting from absorbed moisture.

However, polyamides are semi-crystalline polymers with high degree of crystallinity, which can lead to brittleness, low flexibility and excessive shrinkage.

High moisture absorption is especially a problem for nylon-6 and nylon-66, the most inexpensive polyamides.

Water absorption causes dimensional instability, poor weatherability, and, most importantly, reduces insulation capability.

While nylon-11 and nylon-12 have better moisture resistance and weatherability, the melting temperature may be too low for use in some lamination processes of PV module assembly.