The overall power output of Panasonic's HIT photovoltaic power generating system does not degrade even when the system is operated with high system voltages.
Osaka, Japan- Panasonic Corporation today announced that the resistance to potential induced degradation (PID) of its HIT photovoltaic modules has been confirmed by the Fraunhofer Center for Silicon-Photovoltaics (CSP).
PID is a phenomenon in which the power output of photovoltaic modules is reduced when they are subjected to external factors, such as high temperatures and humidity, under conditions where a high voltage is applied across the internal circuits (photovoltaic cells) and the grounded frame.
HIT photovoltaic modules are renowned for their outstanding performance and quality. Due to the special HIT structure, which refers to a thin mono crystalline n-type silicon wafer surrounded by ultra-thin amorphous silicon layers, the modules have a high efficiency.
With respect to conventional crystalline silicon-based photovoltaic cells, the accumulation of electric charges near the insulating layer on a cell surface is thought to be a direct cause of PID. However, in the case of HIT photovoltaic cells, both surfaces are transparent conductive layers with no insulating layers used. Therefore, no PID is thought to occur. No incidences of PID have been reported from the European, U.S., or Japanese markets.
In collaboration with Fraunhofer CSP, Panasonic set up a test that included both negative and positive voltages. During the test, the HIT modules were subjected to 1,000 volts for 48 hours at a temperature of 50 degrees Celsius with 50% relative humidity. The Panasonic HIT photovoltaic modules exhibited no sign of degradation under such conditions. Of the ten modules used for the test, five were subjected to +1,000 volts, and the other five to -1,000 volts over 48 hours. The results show no evidence of PID.
Michael Seys, in charge of photovoltaic product development of Panasonic Eco Solutions Energy Management Europe, stressed, "Since HIT modules have been proven to be PID resistant by one of the most authorized agencies in the field, our customers can now be fully assured that our modules deliver an excellent performance."
Dr. Matthias Ebert, Head of the Group Module Reliability at Fraunhofer CSP, commented on the test results: "HIT modules differ from standard modules. The challenge for us was to develop a test method that would respect this. By testing for both positively and negatively charged voltages, we can attest to the PID resistance of HIT photovoltaic modules."
Panasonic intends to accelerate the development and commercialization of high quality and highly reliable photovoltaic cells and to work on expanding this business globally.
Panasonic Corporation is a worldwide leader in the development and manufacture of electronic products in three business fields, consumer, components & devices, and solutions. Based in Osaka, Japan, the company recorded consolidated net sales of 7.85 trillion yen for the year ended March 31, 2012. Panasonic's stock is listed on the Tokyo, Osaka, Nagoya and New York (NYSE:PC) Stock Exchanges. The company has the vision of becoming the No. 1 Green Innovation Company in the Electronics Industry by the 100th year of its founding in 2018. For more information on Panasonic, its brand and commitment to sustainability, visit the company's website at http://panasonic.net/.
About Fraunhofer-Gesellschaft and Fraunhofer Center for Silicon Photovoltaics CSP
Research of practical utility lies at the heart of all activities pursued by the Fraunhofer-Gesellschaft. Founded in 1949, the research organization undertakes applied research that drives economic development and serves the wider benefit of society. Its services are solicited by customers and contractual partners in industry, the service sector and public administration.
The Fraunhofer Center for Silicon Photovoltaics (CSP) conducts applied research in the area of crystallization, solar modules and solar wafers. Moreover, the manufacture and assessment of solar cells and modules as well as electrical, optical, and micro-structural materials and component characteristics are also carried out.
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