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Wireless System for In-Situ Monitoring of Moisture Ingress in PV Modules
M. Jankovec, J. Slapšak, S. Mitterhofer, M. Topic
Photovoltaic Modules and BoS Components
Subtopic: PV Module Design, Manufacture, Performance and Reliability
Event: 35th European Photovoltaic Solar Energy Conference and Exhibition
Session: 5CV.3.22
ISBN: 3-936338-50-7
0,00 EUR
Document(s): poster


Recently, a new in-situ measurement technique has been developed using miniature digital relative humidity (RH) sensors [1]. The measurement technique proved to be a valuable tool not only for in-situ monitoring of water concentration in the PV modules exposed to accelerated test conditions in climatic chambers but also for long term outdoor monitoring under field conditions, confirmed by results of continuous humidity monitoring for more than 6500 h of in four different encapsulants. Despite many advantages, it has some weaknesses: Firstly, for communication with sensors it requires wires, which penetrate through the encapsulants and secondly, the size of the sensors does not allow them to be laminated between the cells and glass, where the moisture penetration is of the most interest in PV modules. To overcome the two weaknesses, we designed a completely new in-situ setup, which is based on a near-field communication (NFC) technology [2] and new, ultra-small digital humidity sensors with a footprint of 1.3 x 0.7 mm2 and thickness of 0.5 mm [3]. Up to 21 sensors can be soldered on different prepared locations to a 130 μm thick copper/polyimide foil that also integrates antenna and all required readout electronics. Their ultra-small size enables placement between the solar cells and glass, where only a small cavity is required to be prepared in the glass at the place of the sensors (easily doable by sandblasting). The thin polyimide sheet is shaped in such a way, that it represents a minimal shading of the incandescent light. All measurement data can be read by a dedicated NFC reader or even by any NFC enabled device including modern smartphones, which also provide the power, needed during the measurement and communication cycle.