Advanced Polymer PV System: PVMaT 4A1 Final Report, September 1995 - December 1997

This document reports on work performed by Evergreen Solar, Inc. under this Photovoltaic Manufacturing Technology (PVMaT) subcontract. The purpose of this subcontract was to produce lower module and systems costs through the innovative use of polymeric materials. The impetus behind this approach was the burgeoning use of polymers in such major industries as packaging and automobiles. The marketdemand in these industries has resulted in whole new areas of high-performance, but low-cost, plastics. These developments created fresh opportunities for photovoltaics. Using this approach, a new backskin material instead of Tedlar(TM) (Tedlar is a Dupont trademark) or Tedlar(TM) laminate was developed and tested. This new backskin material allowed us to make a frameless module and novelmounting methods. The latter is referred to as an Innovative Mounting System (IMS). This IMS system, in conjunction with the frameless module, substantially reduces the cost of installed PV systems by reducing labor and materials costs, both in the factory and in field installation. The IMS incorporates several advances in polymers, processing methods, and product design. The advanced backskinmaterial permits elimination of the conventional aluminum perimeter frame, serves to protect and seal the module edge, and allows for direct bonding of multi-functional mounting bars. Electrical interconnection is easier and more reliable with a new junction box that Evergreen has designed after soliciting user feedback. A new transparent encapsulant material, to replace ethylene vinyl acetate(EVA), was developed and tested as part of this subcontract. Early results indicate it will have a number of advantages over EVA, not least of which is better resistance to degradation under light exposure. This new encapsulant can be laminated in air and has also allowed for the development of a continuous, non-vacuum lamination process. The program culminated in the fielding of prototypeproducts with the new encapsulant, new backskin, new junction box, frameless edge seal, and IMS. Feedback and marketing information from potential customers has been actively solicited. Reliability and UL approval requirements have been determined and a number of these already addressed. The net result is a new product that promises a 20% manufacturing and systems cost reduction, as well assignificantly increased system lifetime, as compared to a conventional Al-framed module and mounting. A considerable amount of proprietary technology emerged from the program, seven patents were filed, and two have already been granted (1998).