Evaluating Solar Farm Damage: The Right Technology and a Best Practice Approach Reduces Downtime and BI Losses

Solar power is on the rise, driven by climate change concerns and the transition to renewable energy. The Solar Energy Industries Association estimates there are now over 219 gigawatts of solar capacity installed across the US, with deployments increasing at an average annual growth rate of 26%.

While any severe weather can potentially damage solar panels, hail poses tremendous financial risk. According to Solar Power World, hailstorms caused more than $300 million in damage to solar fields in Texas in the summer of 2022.

AI-powered drone-based thermography is touted as an effective way to assess damage to large solar farms. Yet, this technique is not without its limitations. To ensure effective, timely resolution of weather-related solar farm damage and minimize downtime, it’s essential to apply the optimal approach to assessing damage and develop a strategic plan for testing, repair, and commissioning.

The Complexity of Assessing Damage to Large Solar Farms

For solar farms with hundreds of thousands of modules, assessing and remediating weather-related damage is challenging for several reasons:

• Insurance adjustors and contractors can’t easily walk a massive site, especially one that spans multiple fenced-in areas with separate gates.
• As-built records and baseline data are often lacking, making it difficult to evaluate new damage vs pre-existing conditions.
• After a hailstorm it is tough to distinguish cosmetic damage (such as inconsequential dents in the module frame) from damage that affects component function.
• A large solar farm is likely to have a mix of different panel designs and types, including discontinued models that will be challenging to replace.
• Given the relative infancy of solar power, it’s possible the site operator, adjustor, or repair contractor have limited experience with solar farm damage claims.
• When multiple investors, owners, and contractors are involved, which is common, crucial steps like information sharing and decision-making inevitably slow. 

All the while, the business interruption costs add up significantly every day the facility is out of service or operating at less than 100% capacity.

Drone-Based Thermography: Separating Hype from Reality

Many large (hundreds of thousands of modules) solar farm operators use drone-based thermography to assess the damage. This increasingly popular infrared (IR) scanning technique uses cameras mounted on drones to capture heat signatures that can reveal hotspots, defective strings, or malfunctioning inverters. Drone-based thermography then uses software or AI to analyze the images and identify anomalies, such as cracks, cell temperature variations, reverse polarity, hot spots, underperforming strings, and other indicators of damage.

While drone-based IR scanning is on the rise, this technique poses limitations that can jeopardize effective, efficient damage assessment. Most notably, weather conditions severely impact IR scanning results, with cloud cover, precipitation, frost, and wind all capable of distorting or obscuring images. The camera angle relative to the solar module and the drone’s elevation also impact the accuracy of IR scan images. 

If there are no baseline images—which is often the case—it becomes difficult to compare the condition of solar farm modules pre- and post-storm. Even if the site operator used drone-based thermography to capture baseline images immediately after construction was completed, unless the weather and other conditions were identical, the comparison is not likely to be accurate. And while a drone flyover might seem faster and more cost-efficient than a boots-on-the-ground inspection, it doesn’t provide the accuracy needed to assess solar farm damage thoroughly and with confidence. 

For reasons like these, it is advisable not to rely solely on drone-based thermography when assessing solar farm damage.

Thinking Beyond Drone-Based Thermography

In EDT’s experience, a variety of other testing technologies are worth considering at both the initial damage assessment phase and later, when commissioning the solar farm after repairs are completed. 

Insulation resistance and voltage open circuit (VOC) testing are effective for both damage assessment and repair commissioning. The required equipment is inexpensive, and the results accuracy isn’t weather-dependent. VOC is especially useful as a go/no go indicator for modules, strings, and combiners, although it requires daylight. Insulation resistance is useful for ensuring the absence of ground faults and insulation defects. 

Short-circuit current (ISC) testing is less commonly done, but it can be useful for assessing solar damage at the module level, assuming the operator has the necessary circuit topography knowledge.

IV curve tracing is appropriate at the repair commissioning stage and can be done at the module or string level, although it’s very weather dependent and can prove costly for utility-scale strings. 

Both electroluminescence (EL) scanning and ultraviolet fluorescence (UVF) testing can aid in assessing damage and are especially effective at identifying cracks. However, neither technique provides clear conclusions on module performance, and both are costly to conduct when considering testing 100% of the PV modules installed. Since some solar modules don’t produce UVF, this technique is not widely applicable. 

In addition, visual inspection remains a highly effective way to assess solar farm damage, even across large operations. 

Using the best-fit technologies and approaches to determine the extent of solar farm damage is critical to refining the scope of the repairs, which is vital when the loss involves an insurance claim. Avoiding unnecessary testing also helps to reduce the assessment timeframe and minimize business interruption expenses.

Best Practices for Planning Solar Farm Repairs

When a large-scale solar farm incurs damage that reduces power output, time is of the essence in getting the facility 100% operational and reducing business interruption losses. So it’s essential to develop a repair and commissioning plan that delivers the desired results as quickly as possible.

Several planning best practices are proven to help reduce downtime and the associated costs.

• Use the test results to inform the solar farm repair strategy. Too often, expensive scanning and testing is done to determine solar farm damage, but those test results do not factor into the repair approach. Simpler test approaches might yield sufficient information to guide the repair work.
• Consider a phased repair plan. If the damage is widespread, break the work into logical sections or prioritize the worst-hit areas to speed power restoration and start generating revenue faster.
• Develop an efficient repair timeline. In EDT’s experience with large-scale facilities, the proper sequence of work can actually limit the business interruption loss.
• Find opportunities to make repairs during the damage assessment. Where the damage assessment involves very large solar farms, EDT engineers have identified many instances where the repair work could have been done during the assessment to reduce costs. Rather than simply tally every disconnected connector, the contractor could reconnect those elements in the moment. With the necessary parts and equipment on hand, it's feasible to replace a damaged connector at the point it’s identified.
• Approach repair monitoring strategically. To avoid wasted of over-monitoring, evaluate each project’s needs based on the work scope, the experience of the Owner, any Insurance personnel and the Contractor, and the timeliness and usefulness of the information shared. For a small site with fewer than 1,000 affected modules and frequent progress updates, spot checks might be sufficient. A utility-scale project with tens of thousands of damaged modules, limited communication, and an inexperienced contractor requires full-time site monitoring.   
• Choose an appropriate test sample size. Some tests, like EL testing and IV Curve tracing, are labor-intensive and therefore costly. EDT applies industry standards and engineering judgment to recommend testing sample sizes that can reduce costs while providing accurate and complete information.
• Track repairs thoroughly. Use spreadsheets or other tools to track module repair and replacement, along with the subsequent solar farm commissioning and performance testing. Proper tracking improves accountability, ensures every affected module is remediated, and provides the data to expedite evaluation of future damage incidents.
• Avoid commissioning overkill. Often, it’s practical to simply turn on the modules at the completion of the work and measure the output to confirm that repairs have been done properly.
• Use qualified, vetted experts. An inexperienced contractor, or one with limited direct current (DC) knowledge, could misinterpret test data or perform the necessary rewiring incorrectly. For large-scale solar farm damage, a forensic engineer can recommend approaches that speed and streamline repairs, reducing costly downtime and other expenses.

The forensic engineers at EDT are ideally equipped to bring large solar farms back online quickly and safely, especially after hail or other severe weather strikes. We apply our real-world experience with electrical testing, practical repair strategies, and specialized techniques to assess solar farm damage and develop effective, efficient repair and commissioning plans.

Insurance professionals, legal firms and solar farm owners rely on the experts at EDT to provide accurate and timely evaluations of incidents involving solar farms, including weather damage, construction defects, manufacturing defects and operational issues.

Contact our forensic engineering team for a detailed solar farm damage evaluation or strategic repair plan.

About the Author

Britton C. Hager, P.E. is a consulting engineer with our Cherry Hill Office. Mr. Hager provides consulting in the areas of design and performance of electrical power distribution, transmission, and generation, including fire origin and cause analysis, scope of damage, and repair/replacement economic and technical feasibility analysis. His areas of expertise also include electrical systems and equipment performance during fault and unbalanced conditions, as well as analysis of arc flash events, and lightning strikes.