Utility-Scale solar buyers are no longer buying on certification alone

This is a story about how large solar developers buy equipment, not about home solar directly, but it's worth knowing if you're weighing a rooftop system. For years, solar panels only needed to pass standard safety certifications (IEC and U.S. standards) to be considered good enough to buy. Big buyers are now finding that's not enough, because certification only tests a sample at one point in time and doesn't catch later changes to materials or manufacturing.

The case that prompted this: a developer built a two-phase project using panels supposedly made the same way. One phase had a 1% glass breakage rate; the other hit nearly 15%. Testing traced the problem to an undisclosed change in glass supplier that the manufacturer didn't think mattered, but it did. Separately, industry data shows the typical solar system produced about 98.6% of its expected energy output in 2024, down from around 102% in 2020, with weaker-performing projects dropping from 90% to 85% of expectations.

None of this changes what's on the market for home solar, but it's a reminder that panel quality can vary even within the same product line, and that a manufacturer's spec sheet or basic certification doesn't guarantee consistent long-term performance. If you're shopping for a home system, it may be worth asking whether panels have been tested beyond minimum certification requirements, especially for durability in your area's climate, such as heat, humidity, hail, or heavy wind.