This article was originally published in pv magazine - July & August 2024 Edition.

The quality of solar racking is essential for the structural integrity and longevity of PV projects. Clean Energy Associates (CEA) colleagues Jörg Althaus and Dutt Du discuss some of the most common defects that can derail tracking system quality, while making the case for quality control throughout the supply chain.

Solar mounting and tracking systems are made up of several components, including rails, motors, slew drives, torque tubes, control boxes, and foundation piles. Their production involves material preparation, forming, punching, drilling, welding, cutting, extrusion, milling, painting, and galvanizing. That means significant potential for defects. Motor units alone can be comprised of more than 60 parts, each requiring precise manufacturing to avoid critical defects. Solar project performance depends on stringent quality standards at each step of the production process.

Common Defects

Weaknesses that can compromise system efficiency, safety, and lifespan are categorized as medium, high, and extremely high risk. Galvanization-related defects are a common, medium-risk issue that can cause flux stains and zinc ash inclusion. Surface stains can introduce chlorine or sulfur, which could reduce corrosion resistance. Incomplete or damaged protective coatings can cause bare spots that can drive rust, reducing the mechanical strength of racking equipment and potentially causing system failure. Weak hot-dip galvanization thicknesses can compromise system stability and lead to rust. Adhesive test failures, where galvanization doesn’t properly stick, can cause oxidation of components, affecting functionality and lifespan. Galvanization defects typically become evident over periods of several years. While they don’t present imminent risk of failure, they can indicate more serious quality issues. High-risk defects affect the structural integrity of arrays or mechanical functionality of tracking systems and should be addressed before installation. Welding defects are particularly problematic, as they reduce a racking system’s overall strength. A product’s lifespan can also be reduced by inadequate painting, characterized by a thinner-than-necessary paint layer, causing lower weather resistance. Welding pinholes can present another big risk as these small, isolated voids can form in welding metal when sealing a cavity, increasing a system’s susceptibility to rust in the process. Other problems can occur when components fall outside of their designed tolerances. Ingress protection failure can allow moisture to seep into a slew drive, accelerating wear, driving up internal oxidation, and reducing a system’s overall functionality. Slew drive defects are also significant. Failures in metallographic tests that indicate defects in the casting material can lead to system failure over a five-year period. It is important to ensure the right type of structural steel has been used. The materials should also undergo hardness testing to ensure product durability. Backlash test failures, where slew drive gears don’t fit together precisely, can happen due to imprecise machining. They can lead to component dimensions outside designed tolerances. This can also affect a system’s precision tracking capabilities, significantly reducing the efficiency of power production. Slew drive motors should also undergo load and no-load testing to ensure electrical current is properly translating into motor speed. Defects of extremely high seriousness pose immediate and severe risks to solar racking systems. Manufacturing-dimension deviation can lead to big problems. Here, even slight imprecisions in critical dimensions such as hole pitch can lead to systematic failure during the installation process, causing immediate operational issues. Raw material quality for the structural steel or aluminum used is crucial. Lower- grade metals can make a racking system unable to withstand high wind or snow loads, leading to failure of an overall system and causing major damage to modules. Careful attention to wind engineering, materials science, and structural mechanics testing can help prevent these issues. By understanding such defects and their potential consequences, developers can better appreciate the importance of rigorous quality assurance in solar racking system production and installation. Proactively addressing defects ensures the longevity and reliability of solar equipment and helps to safeguard investment against future failures and inefficiency.

Ensuring Quality

To prevent defects and protect solar investments, developers must implement rigorous quality assurance protocols throughout production and installation. Strategies should include comprehensive quality control, ensuring that suppliers have established robust systems that cover every stage of the production process. Regular third-party inspections, testing, and verification of every component is also a must. It is advisable to choose suppliers with a proven quality track record, along with conducting thorough assessments and audits of supplier production facilities to ensure they adhere to high standards. Suppliers should also maintain detailed records of the production processes and quality checks for each of their components. This helps to trace defects back to their source and implement corrective measures. Buyers should look for suppliers who foster a culture of continuous improvement, where feedback from the field is used to enhance quality assurance processes. Buyers should also ensure that all personnel involved in the manufacturing and installation processes are adequately trained regarding quality standards and best practice. Advanced testing methods, such as metallographic and ingress protection testing, are essential to detect potential defects early on before they affect an overall system. Investing in quality assurance for solar racking is not just about preventing defects, it’s about ensuring the long-term success and reliability of solar installations. By prioritizing quality at every step from material preparation to final assembly, developers can protect their investments and support the broader adoption of renewable energy.

Jörg Althaus is director of engineering services, quality assurance, and quality control at CEA. Before joining CEA, he held various positions at TÜV Rheinland, including being responsible for the strategy development and achievement for TÜV Rheinland’s global PV power plant business.

Dutt Du is project manager for solar racking at CEA. He has experience in mechanical manufacturing and has engaged in projects in countries such as India, Japan, Philippines, the United States, and Spain. Prior to joining CEA, he worked for Chinese racking manufacturer ATEC.

Pillars of Solar Success

Common Defects

Ensuring Quality