California-based technical services firm HelioVolta released its PV Health Report saying the majority of engineering, procurement and construction (EPC) firms have solar projects building or delivered into operation that fail its quality standards. The report, based on field assessments using the company’s SolarGrade software, said nearly 70% of EPCs surveyed have solar projects with significant quality issues.
The latest version of the report evaluated 70 EPCs between May 2021 and May 2025 with over 1,000 projects representing 5 GW of solar assets under construction or in operation. The EPCs included the largest firms with over 10,000 employees down to those with less than 50. Quality issues were endemic across the EPC spectrum, the report said.
The authors justified the nearly 50/50 split between evaluated projects under construction and in operation because quality issues often are not identified and remediated before they are handed off to operations and maintenance (O&M) firms.
The vast majority of the quality issues involved some aspect of wiring, grounding or improper connections that in turn can lead to overheating problems and hotspots in operation. These results are in line with another recent HelioVolta report that said connector failure results in 58% of revenue loss from commercial solar portfolios.
Quality issues not only affect performance in terms of output but also represent major costs due to higher incidents of unscheduled maintenance calls, the report said. Moreover, remediation of significant quality incidents also involves output losses because the system must be at least partially de-energized.
The necessary involvement of subcontractors during construction and specialized O&M providers for functioning assets multiplies opportunities for quality issues to creep into a project. The authors of the report said their analysis found that “experience, size, and geographic reach do not correlate with EPC performance. The only factor that measurably improved construction quality is the implementation of independent oversight.”
The report found that 85% of projects analyzed contained “major issues that require urgent corrective action” while 7% of projects had “critical issues” that triggered immediate de-energization (partial or total) and same-day remediation.
The report’s authors also said that quality issues can be expected to increase in frequency as U.S. developers scramble to meet accelerated deadlines for tax incentives imposed by the One Big Beautiful Bill Act. VDE America’s Brian Grenko said in a recent interview with pv magazine USA the new law has not only introduced uncertainties about project completion, it has created issues of construction and equipment quality from rushing to meet deadlines.
“We’re really concerned about clients rushing to construction to beat a deadline, and what the ramifications of building quickly might be from a quality standpoint,” Grenko said.
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