EVA for Glass/Glass Solar PV Modules: Effect of encasulant storage conditions and process parameters

This work investigates t the effectiveness of glass-glass solar PV module structures used in combination with a EVA as an encapsulant material. The use of EVA in glass-glass structures is in principle discouraged, as a bioproduct of its photo-degradation is acetic-acid, which cannot be released outside the module- as in the case of glass/foil structures - potentially leading to several degradation modes. In particular, the work focuses on the effect of non-optimal EVA storage conditions. The presence of trapped water absorbed when EVA is stored can affect the long-term degradation of the modules. We as well considers photodegradation of polymers under UV exposure and their impact on modules performance. Well-stored EVA shows no sign of degradation up to a UV dose of 504 kWh/m(2), corresponding to approximate to 8-9 years of outdoor exposure in central Europe regions. The effect of poor polymer storage appear firstly after a cumulative UV dose higher than 180 kWh/m(2), corresponding to approximate to 3-4 years of outdoor exposure in a mid-latitude country with a temperate climate.

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Christophe Ballif, Luca Gnocchi, Alessandro Francesco Aldo Virtuani
IEEE, 2021
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https://infoscience.epfl.ch/record/289522?ln=fr

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Climat tempéré

Une région soumise à un climat tempéré, encore appelée région tempérée ou zone tempérée, est dans le sens commun une partie de la surface terrestre où les températures ne sont pas extrêmes, c'est-à-di

Acide acétique

L'acide éthanoïque ou acide acétique est un acide carboxylique avec une chaîne carbonée théorique en C2, analogue à l'éthane, de formule semi-développée CH3-CO-OH ou courte AcOH, où Ac signifie « CH

Modularity

Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used

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

Eleonora Annigoni, Christophe Ballif, Alessandro Francesco Aldo Virtuani

The TISO-10-kW plant, installed in 1982 in Lugano (Switzerland), is made of 288 Arco Solar modules and 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. Power degradation rates were different among modules, and two groups could clearly be distinguished: Group 1, with a remarkably low mean degradation rate of 0.20%/year, and Group 2, with a mean degradation of 0.69%/year. After 35 years in a temperate climate, ~60% of the modules (~70% if considering a 3% measurement uncertainty) still exhibit a performance higher than 80% of their initial value. In this paper, we identify the mechanisms responsible for performance degradation. An extensive characterization of the modules was performed, based on a detailed visual inspection, IV curve measurements, electroluminescence and infrared imaging. When possible, we attempt to correlate module performance losses to specific failure mechanisms. We find that encapsulant aging is the main cause for the increase in the degradation rates over the last 7 years, discussed in Part 1, and we assigned the performance losses in the different groups to changes in the encapsulant used for the lamination. Potential safety threats are also investigated, by measuring the frame continuity, the functionality of the by-pass diodes, and the modules insulation. Finally, we discuss how the analysis of a 35-years-old PV module technology could serve the industry in order to target PV module lifetimes of 40+ years.

2019

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

Eleonora Annigoni, Christophe Ballif, Alessandro Francesco Aldo Virtuani

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.

WILEY2019

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