A novel approach of accelerated ageing tests for high concentration III-V multijunction solar cells through rapid irradiation/thermal cycles

Today, investigations on degradation and failure mechanisms in solar cells are often based on accelerated ageing tests (AAT), where failure effects are reproduced and quantified within a much shorter time period than the actual lifetime. This paper presents a study upon a novel approach of AAT for high concentration photovoltaic (HCPV) cells. The intended approach aims to overcome several limitations encountered in most of the AAT adopted up today, proposing the use of an alternative experimental set-up for performing nearly 400 times faster and more realistic thermal cycles, under real sun conditions (irradiation cycling), without the involvement of any environmental chamber. The cumulative impact of such very rapid irradiation/thermal cycles on the ageing of HCPV assemblies can be determined, both quantitatively and qualitatively, by evaluating specific pre-ageing and post-ageing diagnostic measurements by means of I-V characterization and scanning acoustic microscopy (SAM). The proposed irradiation/thermal cycling arrangement was successfully employed for performing accelerated ageing of both HCPV assemblies (cell receiver and heat sink) and bare HCPV cell receivers. Ultimate goal of this AAT approach is to provide the basis for a future work on the reliability analysis of the main degradation mechanisms and failure propagation in HCPV cell assemblies.