High defect rates drag down solar performance and yield, finds report

A new report on solar system quality found widespread problems in how solar panel projects get built, though the findings mostly concern larger commercial and utility-scale installations rather than typical home rooftop systems. Solar inspection firm HelioVolta reviewed nearly 8 GW of solar projects across the U.S. and Puerto Rico and found that 87% had major issues needing urgent fixes, and 8% had critical problems serious enough to require shutting the system down immediately. Poorly built systems can cost more than 20% more over their lifetime and face three times the repair costs compared to well-built ones.

The report breaks down problems by system type. Rooftop solar, the kind most common on homes and commercial buildings, makes up most of the projects inspected. Commercial rooftop systems had major issues in 88% of cases, with heat-related problems (detected through thermal imaging) showing up in 43% of systems. Ground-mounted systems fared somewhat better, with issues more often tied to grounding and wiring connections. Solar tracker systems, which tilt to follow the sun and are mostly used in large commercial arrays, had the worst record overall, with mechanical wear making existing defects worse over time.

For homeowners, the main takeaway is less about your own rooftop panels and more a reminder that solar quality varies a lot depending on how carefully a system was installed and inspected. The report highlighted two standout projects, a rooftop array in California and a ground-mounted system built for a homeowners association, as examples of what careful workmanship looks like, including clean wiring, labeled components, and proper torque on connections.