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Sumitomo Chemical Develops New Encapsulant Material for Solar Panels - Reducing PID with high transparency unaffected -

Oct. 3, 2014

Sumitomo Chemical has developed a new grade of SUMITATE®, ethylene vinyl acetate copolymer (EVA), as a novel encapsulant sheet material for photovoltaic cells. The newly developed SUMITATE® has the distinct advantage of achieving reduced Potential Induced Degradation (PID) (*1) and high transparency at the same time.

As solar power generation is increasing worldwide, some of mega solar power plants with an output of one megawatt or more have a growing problem of PID, a phenomenon which causes a substantial decline in solar cell outputs. A solution adopted so far for reducing PID is to lower vinyl acetate concentration in EVA. This, however, accompanies another problem of a decline in transparency of encapsulant sheets, which adversely affects power generation efficiency.

The new grade of SUMITATE®, which is based on the Company's proprietary technology, is capable of suppressing migration of ions inside encapsulant sheets, which is responsible for PID. An accelerated PID test (*2) conducted by a third-party evaluation organization has found that the rate of a decrease in electricity output improves significantly from 94%with the Company's current grade of EVA to 2%with the newly developed EVA. In addition, this technology, when used with EVA of a high vinyl acetate concentration, reduces PID and at the same time achieves high transparency, leading to improved power generation efficiency. The benefit of the new SUMITATE® is greater particularly for mega solar power plants where high power generation efficiency is crucial.

Sumitomo Chemical is a long-time stable supplier of high-quality EVA, SUMITATE®, which is highly valued in the market of encapsulant sheet materials for photovoltaic cells. The new grade of SUMITATE® further reinforces the Company's EVA product lineup. The Company is also deploying business with a non-EVA encapsulant sheet material ACRYFT®, ethylene methyl methacrylate copolymer (EMMA) that is superior in long-term durability and free from module troubles that may occur in various ways as a result of acid generation from EVA. Sumitomo Chemical intends to expand the business to meet a wide variety of ever diversifying customer needs. Through this business, Sumitomo Chemical aims to contribute to the development of a sustainable society by helping to reduce environmental impact and promoting wider use of next-generation clean energy.

  1. Potential Induced Degradation (PID): A phenomenon that output of photovoltaic cells declines substantially due to degradation caused by migration of ions in solar panels when the photovoltaic cells are used with high voltage for a long period of time.
  2. An accelerated PID test was conducted under severe conditions: a voltage of 1,000 volts, a temperature of 60 °C, a relative humidity of 85% and a test duration of 96 hours, with the glass surface of solar panels covered with water. The rate of a decrease in electricity output was measured.


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