French scientists examined the effectiveness of various encapsulant supplies, used to laminate photo voltaic cells into modules, in defending the cells and different elements from harm brought on by ultraviolet ( UV) gentle. Their findings present that encapsulants with components particularly designed to soak up UV gentle are inclined to yellow over time, contributing to a wide range of efficiency issues.
The lamination and encapsulant supplies play a key position in defending the within of the PV modules from warmth, chilly, mud, moisture and, considerably satirically, from the sunshine they’re constructed to soak up. Ultraviolet gentle is a reason for many kinds of degradation and lack of efficiency noticed within the discipline, and is prone to be an issue within the newest cell applied sciences.
For the encapsulant materials itself, yellowing throughout lengthy intervals of publicity to gentle is a standard drawback that may trigger a lack of efficiency in itself, and in addition cut back the extent of safety in opposition to different degradation. And that is the main focus of a gaggle of scientists led by France’s Nationwide Photo voltaic Vitality Institute (INES), a division of the French Various Energies and Atomic Vitality Fee (CEA), which is conducting speedy assessments of the modules constructed with completely different encapsulation supplies. .
The group produced single-cell modules, utilizing heterojunction photo voltaic cells laminated at 160 levels with 5 completely different commercially obtainable PV encapsulant supplies – two primarily based on ethylene vinyl acetate (EVA) and three primarily based on polyolefins ( POE). These modules have been illuminated for 4,200 hours, and the samples have been additionally examined for as much as 1,300 hours below ultraviolet radiation and excessive temperatures, to check the consequences of UV gentle alone.
The experiments are described in full within the paper “Photo voltaic cell UV-induced degradation or module discolouration: Between the satan and the deep yellow,” printed in Advances in Photovoltaics. After the check, the modules are inspected visually and measured for fluorescence and present/voltage efficiency.
The outcomes confirmed that the EVA encapsulant was essentially the most affected, and two of the POE samples additionally confirmed slight yellowing. Notably, the three samples with yellowing have been these with components designed to soak up UV gentle. After 4,200 hours of testing, the EVA module was proven to have misplaced 4.2% of its preliminary efficiency.
The research concluded that UV-absorbing components are inclined to degrade, affecting PV module efficiency over time. Nevertheless, the researchers observe that the safety they supply in opposition to different degradation mechanisms is prone to nonetheless justify their use – so long as the photo voltaic cells they defend stay weak to UV degradation. “The destruction of UV absorbers is a matter that impacts the integrity of all the PV module and might result in speedy delamination, and different vital kinds of harm,” the researchers defined. “There’s a problem to seek out new methods to strengthen the photoprotection of the gadget, particularly for the harshest environments, akin to these in deserts.”
Concerning options to this problem, they counsel attempting mineral-based as an alternative of natural UV absorber supplies, and in addition observe that quantum dots will finally turn out to be an alternate resolution, though they’re nonetheless obtainable. within the early levels of analysis. Lastly, they counsel investigating UV-absorbing glass, changing the necessity for encapsulant components.
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