Thermal Aging Assessment of Photovoltaic Cable Insulation Using XRF Spectroscopy
B. Stergar(1), J. Počivalnik(1), D. Kuhar(1), E. Simonič(1), S. Seme(1,2), K. Sredenšek(1,2) 1. Faculty of Energy Technology, University of Maribor, Krško, Slovenia 2. Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia 2026-06-27

Abstract

The increasing deployment of photovoltaic systems requires reliable cable infrastructure capable of withstanding long-term thermal and environmental stresses. Polymeric insulation materials used in photovoltaic cables are susceptible to thermal degradation, which can progressively deteriorate their mechanical and dielectric properties. A key degradation mechanism of polyvinyl chloride insulation is dehydrochlorination, which leads to chlorine loss and structural changes in the polymer matrix. This paper investigates the applicability of portable energy-dispersive X-ray fluorescence spectroscopy as a non-destructive method for assessing thermal aging of photovoltaic cable insulation. Special attention is given to multilayer insulation, as the analyzed photovoltaic cable comprises two distinct layers (an inner white layer and an outer black layer) that may differ in composition and thermal response. Cable samples were subjected to controlled thermal exposure ranging from room temperature to 150 °C, covering both typical operating conditions and accelerated aging scenarios. Elemental analysis focused on monitoring chlorine content as the primary indicator of degradation. The results reveal a temperature-dependent decrease in chlorine content, with moderate changes up to 110 °C and a more pronounced decline above approximately 130 °C, indicating the onset of accelerated degradation. The findings confirm that portable X-ray fluorescence spectroscopy enables rapid, non-destructive evaluation of insulation condition, although careful interpretation is required for complex multilayer cable systems.

Key words: photovoltaic systems, cable insulation aging, polyvinyl chloride degradation, portable X-ray fluorescence spectroscopy, thermal reliability.

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