Glass is a unique material used for its chemical stability and visual transparency. It is commonly used in solar panels as a protective outer layer.
In its annual PV Module Index, the Renewable Energy Test Center (RETC) examined emerging issues in solar glass manufacturing and field performance. It found reports of a concerning rise in solar panel glass spontaneously breaking in the field, sometimes even before commissioning.
Teresa Barnes, Ph.D., manages the Photovoltaic Reliability and System Performance Group at the National Renewable Energy Laboratory (NREL). Barnes and her colleagues at NREL reported the issue.
“Spontaneous glass breakage is an example of a failure mode that we didn’t used to see. When I first started working on solar module reliability seven or eight years ago, we mostly heard about glass breakage when there were sloppy operations and maintenance practices,” said Barnes.
Now, this is no longer the case, and the NREL reliability team is regularly receiving reports of glass breakage in silicon modules unrelated to direct damage from maintenance or storm impacts. The team found that over time, the average quality of solar glass appears to be decreasing.
“It used to be the case that modules would pass the IEC 61215 static load test with a big safety factor,” said Barnes. “Today, modules are either barely passing the base static load test or they are not passing with higher safety factors. Some new module designs are simply not passing the minimum static load test.”
The NREL team has begun to hypothesize that glass damage in solar panels is undergoing a similar process to a car windshield in need of replacement. When a windshield takes impact damage, often it only shows up as a small star-shaped mark that seems insignificant. But when extreme weather conditions with very high or low temperatures cycle through, the severity of the damage is fully realized, and suddenly a large crack is visible across the whole surface.
“We think a similar dynamic could be a root cause of spontaneous solar glass breakage,” said Barnes.
This rise in breakage is likely due to the trend solar glass getting thinner over time, said NREL. Mike Pilliod from Central Tension, who spoke at NREL’s 2024 PV Module Reliability Workshop said any manufacturer can temper glass that is 3 mm. But under 3 mm, glass tempering is a difficult process. He said that as glass gets thinner, it takes fewer defects to create strength-limiting flaws in the glass. These flaws are actively being studied by NREL to understand some of the potential pitfalls of using thin glass in solar manufacturing.
Barnes warned that it may be a combination of effects that are making glass breakage a larger threat that before. Modules are getting larger, frames are getting thinner, and mounting rails are getting closer together. All these factors lead to “large, floppy modules” that are putting more pressure on the glass surface, which is also getting thinner in many modules.
The NREL team said at this year’s PV Module Reliability Workshop, manufacturers began speaking about introducing thicker frames and wider mounting positions.
“As people better understand how the module system interacts, they can work to optimize how loads are balanced out,” said Barnes. “The pendulum in that balancing act may already be swinging back toward the integrity of the frame and the mounting rail.”
While some module providers are focused on frames and mounting, others have introduced tempered glass modules that are marketed as hail-hardened and resilient to extreme weather.
RETC asked Barnes about the recent catastrophic losses in Texas, where hailstorms caused hundreds of millions of dollars in damage to operational solar assets.
GCube Insurance, an underwriter for renewable energy, said despite being only 1.4% of total number of insurance claims filed, about 54% of incurred costs of total solar losses can be attributed to hail. This is based on data collected by Gcube over the past five years. Average costs totaled $58 million per claim.
“Ten years ago, people would run you out of the meeting on a rail if you mentioned climate-specific module designs. The consensus was that this would simply be too expensive,” said Barnes. “Now climate specific modules and climate-specific testing are starting to look viable because we are seeing more of an emphasis on total system costs. It is entirely possible that we could see hail-hardened modules, especially in a market like the United States, where it could be worth paying more up front for hail resilience.”
This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: editors@pv-magazine.com.
What’s going to happen to all the damaged solar panels ? And when they stop working? A solar land fill!
Would be better article if you identified specific panels that tend to break.
This article once again proves solar panels just aren’t right and safe for producing energy. During construction of these so-called solar panel fields, the natural environment is destroyed. Then when the “fields” are put into operation the great potential for eternal damage to the environment exists. Other than money to the landowner, no positive impact will occur to the surrounding landowners. Let’s get behind this effort and do what is necessary to kick the solar fields out of our backyard.
This report didn’t mention the country of origin of these solar panels where the glasses spontaneously breaks. I’ve traveled to China more than 50 times over the last 20 years, and I can assure you that the Chinese are simply cheating by making thinner, glass and glass that does not meet Standards. I’ve probably visited more than 100 different factories, including a dozen making photovoltaic products.. Most of them were conscientious and tried to make good products. However, in the last 10 years tensions between the US and China have escalated over the South China Sea and the Chinese are doing whatever they can to increase their market share. Often this includes selling products below cost or cheating on recognized industry standards to gain sales.
Could the glass be made in a oval form like a magnifying glass thickining at the middle or make the glass with the same concept as a 3D picture with different angles as you look at it
I agree with the statement that solar panels are getting bigger and bigger but the protection glass is prone to cracks and breakages especially during transporting. Need to control it’s size.
It would be nice to see the data on how thickness of glass correlates to failures as well. REC has talked for a long time about micro-fractures in solar cells due to flexing panels too much during installation, but I’m curious if that’s what’s happening with the thinner glass as well.
There’s a lot of fear-mongering over the longevity of solar, but the failure rates are still exceptionally low. A lot of the data comes from commercial and industrial sites as well, which typically source cheaper & lower-quality modules than a residential system would use. Some maintenance and failure is expected, but I would be surprised if this issue was persistant across all models of solar panels, and not just the more commodity modules.
These solar panels and windmills are the worst things ever invented. Neither are recyclable as claimed or do the job needed. They take to much land and will take up even more that would invade too much or our environment with either use or waste from them. Our electricity works better and is much more reliable. Stop with the nonsense and just try making our electricity better.