Characterization of multicrystalline silicon modules with system bias voltage applied in damp heat
By: P. Hacke ... [et al.].
Contributors: National Renewable Energy Laboratory (U.S.); Stichting Energieonderzoek Centrum Nederland; E.C. Photovoltaic Solar Energy Conference (25th : 2010 : Valencia, Spain)
Series: NREL/CP -- 5200-49344; Conference paper (National Renewable Energy Laboratory (U.S.)) -- 5200-49344.
Publisher: National Renewable Energy Laboratory
Published: 2011
Place of publication: Golden, CO]
Language: eng
Format: [electronic resource] /
Subjects: Photovoltaic cells; Materials; Testing; Solar cells; Accelerated life testing; Reliability (Engineering)
Description: As it is considered economically favorable to serially connect modules to build arrays with high system voltage, it is necessary to explore potential long-term degradation mechanisms the modules may incur under such electrical potential. We performed accelerated lifetime testing of multicrystalline silicon PV modules in 85 degrees C/ 85% relative humidity and 45 degrees C/ 30% relative humidity while placing the active layer in either positive or negative 600 V bias with respect to the grounded module frame. Negative bias applied to the active layer in some cases leads to more rapid and catastrophic module power degradation. This is associated with significant shunting of individual cells as indicated by electroluminescence, thermal imaging, and I-V curves. Mass spectroscopy results support ion migration as one of the causes. Electrolytic corrosion is seen occurring with the silicon nitride antireflective coating and silver gridlines, and there is ionic transport of metallization at the encapsulant interface observed with damp heat and applied bias. Leakage current and module degradation is found to be highly dependent upon the module construction, with factors such as encapsulant and front glass resistivity affecting performance. Measured leakage currents range from about the same seen in published reports of modules deployed in Florida (USA) and is accelerated to up to 100 times higher in the environmental chamber testing.
Notes: Title from title screen (viewed July 26, 2011).

"July 2011."

"Presented at the 25th European Photovoltaic Solar Energy Conference and Exhibition, Valencia, Spain, September 6-10, 2010."

"Energy Research Center of the Netherlands."

Includes bibliographical references (p. 6).

DE-AC36-08GO28308

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