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In the constant race to do more with less, solar panels in the utility-scale space have been getting more powerful but also larger, heavier and bulkier. To cut costs and weight of the two largest components on a bifacial module, manufacturers reduced each piece of glass to a 2-mm thickness. But soon, a new problem arose on bifacial projects sited in the middle of the United States: these panels with thinner glass were sustaining more damage than panels with backsheets during the region’s common hailstorms. Maybe cheaper, lighter glass wasn’t the right choice.
Solar panel manufacturers found that the easiest and, honestly, most obvious thing to do was go back to the traditional 3.2-mm glass thickness. JinkoSolar recognized the hail problem in 2021 and released the thicker-glass bifacial module EAGLE G5b to the North American market.
“There was a mass migration to dual-glass products, mostly for cost reduction, and the glass was getting thinner and thinner. We were anxious about hail exposure and the thinning out of the glass,” said Adam Detrick, U.S. director of product management and technical services for JinkoSolar U.S. “We decided to differentiate and keep our eye on hail, so we went with a 3.2-mm glass, transparent backsheet panel.”
Just using a thicker piece of glass isn’t the full story though. Companies like Jinko, Trina Solar and LONGi use tempered instead of heat-strengthened glass on its hail-resistant brands. Tempered glass is five-times stronger than heat-strengthened glass, said Brenden Frazier, product manager at Trina Solar US.
“The front glass being a greater thickness allows that tempering process to be done more easily,” he said. “A lot of typical 2-mm glass is heat-strengthened, and there is a good amount of strengthening when you put it through that heat process, but it’s not nearly as strong as a fully tempered glass.”
Trina developed a hail-resistant version of its Vertex N bifacial module that will begin shipping Q2 2025. In addition to tempered glass, the module has a transparent backsheet. Backsheet quality a decade ago was questionable, another reason why brands moved to dual-glass designs, but things have improved, especially with transparent backsheets.
“A few years ago, we would highlight a backsheet module as being a concern,” Frazier said. “But we’ve done a lot of work in that realm, a lot of work with our TOPCon reliability and extended backsheet reliability tests. We’re putting this hail-resistant module through full testing and have full confidence in the performance and reliability of the backsheet.”
As the first to really explore hail-resistant designs, Jinko worked with DuPont on a Tedlar-based transparent backsheet that has proven itself over the last three years on Jinko projects. Detrick said that as the 3.2-mm glass, transparent backsheet design is now catching on with other brands promoting hail-resistant modules, Jinko is pushing the envelope again, this time back to dual-glass models.
“When we looked at deploying our TOPCon product to the United States, we looked at how we could do this even better,” he said. “Our new G6X, introduced in 2024, is a dual-glass version of the hail-resistant product. It’s not just glass thickness; there are multiple elements that go into a hail-resistant module. Construction and materials matter. We have a recipe on what we think works best with a dual-glass format. We’ve branded it EAGLE Talon Glass, and that’s what we put on the G6X product.”
Jinko won’t reveal the properties of its proprietary glass technology, but modules with EAGLE Talon Glass have been tested by Kiwa PVEL and RETC and received top performer and high achiever markers. While the IEC testing standard requires solar panels to withstand 25-mm hailstones traveling at 23 m/s, Jinko’s EAGLE G6X line can withstand 55-mm hailstones at the same speed — larger than a standard golf ball. With the probability of regular golf-ball sized hail events increasing due to climate change, Jinko’s dual-glass hail-resistant panels should perform well in the United States.
“We learned that the best solution isn’t necessarily completely intuitive,” Detrick said. “Everyone is just talking about thicker glass being better, and we keep coming back to that not being the only thing, there are other factors to consider.”
Although the details of Jinko’s new module design aren’t published, one can compare datasheets. Jinko’s 2-mm, heat-strengthened dual-glass module has a height of 30 mm and weighs 68 lb. The 3.2-mm tempered, transparent backsheet module is 35 mm and 61 lb. The new dual-glass module using EAGLE Talon Glass is back to 30 mm but weighs 83 lb.
The new design from Jinko shows that not all solar panels are easy to install solo, but also, not all solar panels need to be hail-proof. Hail is not a problem everywhere in the United States, so solar projects in Nevada, for example, don’t need to have the heaviest, strongest panels available. That’s why all the brands making hail-resistant modules are still making the heat strengthened 2-mm dual glass designs along with 3.2-mm alternatives.
“We don’t want to look at our hail-resistant modules myopically like, ‘Here’s a BOM that does great for hail. It has to do these other things too,’” Detrick said. “With its heavier, thicker construction, EAGLE G6X has a much higher wind resistance than standard modules so we’re advertising it globally as a complete extreme weather solution.” |
