From the magazine
Solar steel does not become unusable when rust occurs. Designers build in a material thickness margin that is above the minimum required to withstand the expected loads. But when corrosion affects electrical connections, it can shift from a reliability issue to a safety issue.
Corrosion concentrates at interfaces such as bolted joints, welds and cut edges, where moisture, dirt and movement can erode protective coatings.
Fasteners are a common pain point. Rust can eat away at bolts, making routine maintenance labor-intensive cutting and replacing. It can also affect the connection itself when small changes in tolerances and friction between contact surfaces cause movement under dynamic and cyclic loading, accelerating wear.
In practice, electrical corrosion often occurs in the form of compromised ground continuity, by interrupting the metal-to-metal path that carries fault current from module frames through the rack system to the ground conductors. This loss of continuity complicates error detection and raises safety issues. At terminals, cable lugs and connectors, corrosion can increase resistance, generate heat and physically separate conductive surfaces. In the worst case, this combination can contribute to disconnection, arc faults and increased fire risk.
Causes of corrosion
Most corrosion problems have three underlying causes: protection that is poorly designed for the environment in the first place, protection that becomes damaged in the field, and component choices that accelerate corrosion at interfaces.
Large scale tracker and rack structures usually rely on hot dip galvanizing for protection. Zinc acts as a sacrificial layer through galvanic corrosion, with the zinc preferably corroding first and protecting the underlying steel until the zinc layer is depleted.
This makes the galvanization thickness a central variable in the measurement of the corrosion resistance of a part. The required thickness depends on the environment and the design life. If the coating begins to become thinner than specified, or if the specification does not reflect the actual exposure of the site, the zinc layer may be used up faster than planned and corrosion of the underlying steel may begin much sooner than a project manager expects.
A system specification that may be perfectly suitable for an inland location may be completely inadequate for a coastal location, or a location with highly corrosive soil properties. There is no one-size-fits-all specification for corrosion protection.
If corrosion occurs sooner than expected, begin coating thickness measurements to confirm that the zinc coating is present and that it meets the engineer’s specification. If results are abnormal or inconsistent, metallurgical analysis can help determine the cause, for example by characterizing the coating and steel composition and confirming how the protective system was applied.
Even when galvanizing is done properly, tires, forks, lifting points and stacking can scrape off coatings. Screwing connections can remove protective material on the threads. These exposed areas need to be updated often, and teams sometimes underestimate how consistently updating needs to happen across tens of thousands of connections.
When materials are left in wet conditions for extended periods of time, or when touch-ups are missed, corrosion can develop at exposed points. Without close inspection, it is difficult to determine where the protective layer is intact and where it has been removed. Zinc galvanizing typically gives steel products a gray and hazy appearance, but sometimes, especially when applied in thinner layers to parts without a high risk of corrosion, it can look almost as smooth and shiny as bare steel.
Finally, component selection and compatibility can accelerate corrosion at critical interfaces. Cross-coupling of connectors – joining components from different manufacturers that were never intended to fit together – can introduce dissimilar metals and cause fit tolerances that promote galvanic corrosion. As resistance increases, heating occurs at the interface, which is potentially both a reliability and safety issue.
Best practices
Corrosion control works best when teams view it as a lifecycle program rather than a warranty clause. This requires clear specifications up front, verification at the right points in the supply chain and a monitoring plan once the site is in use.
Prevention starts with corrosion specifications related to the actual location. Match layer thickness and materials to environmental realities – including coastal exposures, soil conditions, drainage patterns and expected wet-dry cycles.
One of the most impactful steps is prior verification. Many manufacturers outsource galvanizing, so quality control must extend to the galvanizing plant itself. Pre-shipment coating thickness checks may present problems if repairs are as simple as possible; waiting for the material to reach the site often limits on-site repair, monitoring or replacement options.
Packaging and handling should minimize damage from scraping and impact. Teams should avoid long periods in moisture-retentive conditions, and keep steel off bare ground and out of puddles where possible.
Consistent touch-ups are essential, using cold-dip galvanized materials wherever crews encounter exposed steel, including on threads and cut edges.
When corrosion occurs, a clear inspection and diagnostic workflow helps teams respond with measurements rather than assumptions. A practical approach starts with visual walkdowns to map corrosion clusters. Layer thickness measurements follow at representative locations, especially at interfaces and other high-risk points.
Metallurgical analysis is a separate, deeper diagnostic step. Use it if thickness results are inconsistent, if corrosion appears unusually severe, or if there is reason to suspect problems with the coating system or base material. This sequence helps distinguish cosmetic coloration from true coating depletion and material loss.
Owners can reduce long-term risks through periodic inspections rather than reactive repairs. Check the galvanization thickness every five years. Interpret the results using the original corrosion specification or a revised thickness loss schedule.
With regard to electrical corrosion risks, the mitigation includes specifying approved outdoor hardware for terminals, lugs and connection components. Avoid cross-pairing of connectors and treat any sign of heating, discoloration or loosening at connections as an indication for inspection, torque verification and possible replacement.
Projects that stay one step ahead of corrosion treat it as a measurable and controllable performance variable. This requires clear acceptance criteria, documented remediation practices and periodic verification. Nicholas Hudson and Ankil Sanghvi
About the authors
Nicholas Hudson is a principal engineer at Clean Energy Associates (CEA). Hudson is a US-trained civil engineer and a licensed professional engineer. After working at SunPower for five years, he joined CEA. He brings deep experience in construction engineering, site assessment and solar due diligence. Based in Austin, Texas, he leads analyzes of site conditions, permitting, and construction risk for utility-scale projects.
Ankil Sanghvi is a senior engineering manager at CEA with over 11 years of experience in the PV industry, specializing in field inspections, fault analysis and risk mitigation for utility and commercial assets. He leads site inspection and field testing programs and has overseen more than 1,200 PV system inspections across multiple regions, supporting more than 26 incident and loss investigations involving fires, equipment failures and extreme weather events.
The views and opinions expressed in this article are those of the author and do not necessarily reflect those of the author pv magazine.
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