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杏彩彩票注册邀请码unlight shines through solar panel backsheet.
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杏彩彩票注册邀请码ehind the solar panel, sunlight can be seen shining through the plastic backsheet in the grid-shaped space between the solar cells.

杏彩彩票注册邀请码杏彩彩票注册邀请码nlike diamonds, solar panels are not forever. 杏彩彩票注册邀请码ltraviolet rays, gusts of wind and heavy rain wear away at them over their lifetime. 

杏彩彩票注册邀请码anufacturers typically guarantee that panels will endure the elements for at least 25 years before experiencing significant drop-offs in power generation, but recent reports highlight a trend of panels failing decades before expected. 杏彩彩票注册邀请码or some models, there has been a spike in the number of cracked backsheets — layers of plastic that electrically insulate and physically shield the backsides of solar panels.

杏彩彩票注册邀请码he premature cracking has largely been attributed to the widespread use of certain plastics, such as polyamide, but the reason for their rapid degradation has been unclear. 杏彩彩票注册邀请码y closely examining cracked polyamide-based backsheets, researchers at the 杏彩彩票注册邀请码ational 杏彩彩票注册邀请码nstitute of 杏彩彩票注册邀请码tandards and 杏彩彩票注册邀请码echnology (杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码) and colleagues have uncovered how interactions between these plastics, environmental factors and solar panel architecture may be speeding up the degradation process. 杏彩彩票注册邀请码hese findings could aid researchers in the development of improved durability tests and longer-lived solar panels. 

杏彩彩票注册邀请码racks in backsheets often show up first near certain features — such as the grid-shaped space in between the blue or black electricity-producing solar cells — and can eventually propagate through the entire thickness of a sheet. 杏彩彩票注册邀请码hese defects make way for oxygen and moisture to infiltrate and damage the interior where the cells lie and also allow electrical current to escape, increasing risks of electrocution. 

杏彩彩票注册邀请码杏彩彩票注册邀请码f left outside for long enough, any plastic-based backsheet will start to fall apart, but not all backsheets are created equal. 杏彩彩票注册邀请码ome plastics deteriorate much more rapidly than others. 

“杏彩彩票注册邀请码n the 2010 to 2012 timeframe, many modules were deployed containing polyamide-based backsheets, which presented dramatic cracking failure in as little as four years despite meeting standard requirements,” said 杏彩彩票注册邀请码iaohong 杏彩彩票注册邀请码u, 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 materials engineer and co-author of the study. 

杏彩彩票注册邀请码wo intersecting cracks on a solar panel backsheet.
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杏彩彩票注册邀请码racks often form on solar panel backsheets in straight lines, along the gaps between solar cells.

杏彩彩票注册邀请码杏彩彩票注册邀请码o get to the root of polyamide’s degradation problem, 杏彩彩票注册邀请码u and her team acquired backsheet samples from solar panels deployed in regions around the globe, including sites in the 杏彩彩票注册邀请码.杏彩彩票注册邀请码., 杏彩彩票注册邀请码hina, 杏彩彩票注册邀请码hailand and 杏彩彩票注册邀请码taly. 杏彩彩票注册邀请码ost of the panels, which were in use from three to six years, showed clear signs of premature cracking. 

杏彩彩票注册邀请码ith the weathered backsheets in hand, the researchers conducted a gamut of chemical and mechanical tests to examine the patterns and severity of degradation throughout the depth of the sheets. 杏彩彩票注册邀请码he results, in the journal 杏彩彩票注册邀请码rogress in 杏彩彩票注册邀请码hotovoltaics: 杏彩彩票注册邀请码esearch and 杏彩彩票注册邀请码pplications,杏彩彩票注册邀请码 showed that the areas of the sheets that had undergone the worst cracking were those that had become the most rigid. 杏彩彩票注册邀请码nd curiously, the most brittle areas were on the inner side of the sheets, 杏彩彩票注册邀请码u said. 

杏彩彩票注册邀请码杏彩彩票注册邀请码ow could the quality of the walled-off interior diminish more quickly than the exposed outer layer? 杏彩彩票注册邀请码u and her team speculated that the sunlight-induced degradation of the top side of the encapsulant — a film that surrounds the solar cells — produced damaging chemicals that descended toward the backsheets, speeding up their decay. 杏彩彩票注册邀请码f true, the proposed mechanism would explain why cracks form in between solar cells, as chemicals could find passage to the back through these regions. 

杏彩彩票注册邀请码杏彩彩票注册邀请码he researchers identified acetic acid as a prime suspect, as it is known to be harmful to polyamide and is produced during the degradation of a polymer commonly used as an encapsulant, called ethylene vinyl acetate (杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码). 杏彩彩票注册邀请码o test their hypothesis, the researchers stowed several polyamide strips away in vials of acetic acid and then, after five months, analyzed how they decayed compared with strips placed in either air or water. 

杏彩彩票注册邀请码 cross section of a solar panel shows how stressors localize between solar cells and contribute to the accelerated cracking of backsheets.
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杏彩彩票注册邀请码lthough moisture and water wear away at the entire outer surface of backsheets, they crack more quickly in the area between solar cells where sunlight shines through. 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 researchers propose that degradation is worse there because acetic acid, which forms when sunlight hits the the rubbery upper layers, can pass between the solar cells toward the backsheets, causing them to decay from the inside out. 

杏彩彩票注册邀请码nder the microscope, cracks mirroring those from the weathered backsheets appeared on the surface of the plastic strips exposed to acetic acid, which appeared much worse than on those that had been in air or water. 杏彩彩票注册邀请码hemical analysis showed that degradation products of polyamide were higher in the acetic-acid-exposed strips, providing further evidence that the acid accelerates the deterioration of the backsheet material. 

杏彩彩票注册邀请码杏彩彩票注册邀请码he study highlights the interplay between solar panel components (the 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 encapsulant and polyamide backsheet in this case) as a potentially critical factor to consider when designing solar panels that are built to last.

杏彩彩票注册邀请码hese new insights into premature failures could also become valuable to 杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码杏彩彩票注册邀请码 researchers and others who seek to replicate the degradation process in the lab as a way to test and predict the longevity of solar panel components.


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