35 years of photovoltaics: Analysis of the TISO‐10‐kW solar plant, lessons learnt in safety and performance—Part 2

Abstract

The TISO‐10‐kW plant, installed in Lugano (Switzerland) in 1982, is the first grid‐connected PV plant in Europe. In a joint publication (part 1), we presented the results of the electrical characterization performed in 2017—after 35 years of operation—of the 288 Arco Solar modules constituting the plant. Power degradation rates were different among modules and two groups could clearly be distinguished: group 1, with a remarkably low mean degradation rate of −0.2% per year, and group 2, with a mean degradation of −0.69% per year. After 35 in a temperate climate, approximately 70% of the modules (considering a ±3% measurement uncertainty) still exhibit a performance higher than 80% of their initial value. In this paper, when possible, we attempt at correlating module performance losses to specific failure mechanisms. For this sake, an extensive characterization of the modules was performed using visual inspection, IV curve measurements, electroluminescence, and infrared imaging. We remarkably find that module degradation rates are highly correlated to the aging pattern of the encapsulants used in module manufacturing. In particular, a specific formulation of the encapsulant (PVB), which was used only in a minority of the modules (approximately 10%), leads to degradation rates of −0.2% per year, which corresponds to a loss in performance below 10% over 35 years. Potential safety threats are also investigated, by measuring the frame continuity, the functionality of the bypass diodes, and the module insulation. Finally, we discuss how the analysis of a 35‐year‐old PV module technology could benefit the industry in order to target PV module lifetimes of 40+ years.

Importance of atmospheric aerosol pollutants on the degradation of Al2O3 encapsulated Al‐doped zinc oxide window layers in solar cells

“…To guarantee reliability of newly developed photovoltaic (PV) modules for several decades, the relevant failure mechanisms of PV materials and their assemblies need understanding. These mechanisms can be analysed for the modules that have been in service for 25–35 years now 1‐3 . Failure modes of newly developed materials can, however, only be obtained by employing some specific accelerated degradation procedures.…”

“…These mechanisms can be analysed for the modules that have been in service for 25-35 years now. [1][2][3] Failure modes of newly developed materials can, however, only be obtained by employing some specific accelerated degradation procedures. A reliable accelerated test should favour the degradation mechanisms relevant for outdoor conditions, so its design requires to know the key factors controlling the environmentally assisted degradation of PV materials and assemblies.…”

“…The common practice to protect PV modules from humidity is to use glass in combination with thick organic encapsulates, for example, ethylene-vinyl acetate (EVA) or polyvinyl butyral (PVB). 3 The added value of thin layer PV technology, like copper indium gallium selenide Cu (In,Ga)Se 2 (CIGS) solar cells, is that they offer a possibility to produce flexible modules, 11 for which the protection by thick glass-glass assembly is not interesting. These modules use thin polymeric front/back sheets which are lightweight and flexible.…”

Photovoltaic lifetime forecast model based on degradation patterns

“…The first set of data are those of the TIcino SOlare (TISO)-10-kW PV plant in Lugano (Switzerland). 25,26 The TISO-10 PV system has been connected to the grid since 1982 and is the oldest installation of this kind in Europe (we shall refer to them as "TISO modules" hereafter).…”

Comparison of Degradation Behavior of Newly Developed Encapsulation Materials for Photovoltaic Applications under Different Artificial Ageing Tests

“…Bare polymer films, thermally pre-treated but not encapsulated within the typical PV module stack configuration have been the object of this study. The choice of using films has been made to better understand how environmental factors influence the degradation behavior of the polymer itself directly exposed and to have an insight of what could happen to the materials in case additional degradation modes, such as backsheet cracks and extensive delamination, might occur [ 23 , 24 ]. The work aims to make a step forward in understanding and comparing performances of newly developed material with respect to the state-of-the-art EVA by means of a comprehensive analysis that has not been performed before.…”