C-DRONE GUIDE · 5 AUGUST 2026
Hail or storm damage assessment on a solar farm by drone: method, insurance file, price
A large-hail storm can crack the glass of several thousand modules on a ground-mounted solar farm within minutes — without the damage always being visible from the maintenance aisles. Every cracked cell that keeps producing under load concentrates heat locally: an electrical risk as much as a yield loss that worsens if it is not spotted in time. On a site spanning dozens of hectares, the challenge is not just noting the damage — it is locating the affected modules, table by table, fast enough to isolate dangerous strings, build the insurance file and target replacement instead of swapping out whole rows out of caution. Here is how a drone flight combining high-resolution photography and infrared thermography documents hail or storm damage on a solar farm, and what it costs in 2026.
Published on 5 August 2026, reviewed on 25 August 2026 — regulations in force as of August 2026.
Why hail damage doesn't always show to the naked eye
A hail strike on a photovoltaic module produces two very different kinds of damage to deal with. Visible breakage first: shattered or starred glass, a bent frame, a torn-off connector — spottable by walking the aisles, provided every table is actually inspected rather than sampled. Invisible cell cracking second: the glass looks intact, but the cell underneath has fractured, degrading its electrical conduction locally. Under load, that spot starts running hotter than its neighbours, with no outward sign — until the degradation worsens, spreads thermal stress to adjacent cells, or triggers a hot spot severe enough to pose a long-term fire risk.
A study by Katinić and Bošnjaković published in 2025 in the journal Technologies reviews the degradation mechanisms of modules under hail impact — glass cracking, cell micro-cracks, electrical faults — and notes that combining visual inspection with infrared thermography is the most reliable diagnostic method for telling the two kinds of damage apart across a whole plant (see the study on Google Scholar). That is exactly what a dual-sensor drone flight delivers: covering the whole site with both methods, where a walk-through with a handheld thermal camera would take several days and still stay partial.
The method: one photo pass, one thermal pass
The emergency mission runs in two passes, which can be decoupled in the schedule. The high-resolution RGB photo pass comes first: unlike thermography, it does not depend on a minimum irradiance and can therefore fly as soon as the weather allows, even under a hazy sky — the urgency after a loss event rarely leaves the luxury of waiting for the ideal weather window. This flight documents visible breakage table by table: starred glass, bent frames, debris on the ground, whole panels torn off by wind in a storm event. The infrared thermal pass comes next, flown under the sufficient-irradiance conditions detailed by the IEC 62446-3 standard (see our guide to drone thermography of a solar farm), and reveals the hot spots that betray a cracked cell under glass that otherwise looks intact.
Cross-referencing both images on every module is what turns a simple survey into an actionable diagnosis: a study by Kuo, Chen and Huang published in 2023 in Energy Conversion and Management, carried out on a 410 kW Taiwanese plant with close to 1,500 modules, shows that a system combining drone-based infrared and RGB imaging can automatically detect, classify and locate defects with better than 99% accuracy, the visible image confirming the likely cause of the hot spot flagged in thermal (see the study on Google Scholar). On a multi-megawatt plant, this automated cross-referencing is what lets operators sort, in a few days rather than several weeks, the modules that warrant replacement from those that can wait for the next maintenance campaign.
The file sent to the insurer and how it fits with the loss adjuster
The typical deliverable combines a georeferenced orthophoto of the whole site, matched visible and thermal images for every suspect module, and a correspondence table identifying each anomaly by its exact position (table, row, string). When the site already has an earlier thermal map — from a periodic audit compliant with IEC 62446-3 — comparing it with the post-loss survey pins the new hot spots on the weather event rather than pre-existing degradation, an argument that carries real weight in the negotiation with the insurer. It is the same principle behind our guides to hail damage assessment on a vehicle fleet or crack diagnosis after drought subsidence: dated evidence, compared against a prior state, carries more weight than a single one-off record.
This aerial survey complements — never replaces — thorough electrical characterisation of the modules flagged after sorting — current-voltage curve, electroluminescence — the only method able to confirm the actual power loss and price an accurate settlement. The case for systematising this kind of large-scale survey after an extreme weather event is no longer hypothetical: a study by Perry published in 2025 in Progress in Photovoltaics, covering post-loss satellite imagery of more than 11,300 photovoltaic systems after an exceptional 2023 hailstorm in Austin, Texas, shows that damage prevalence and severity vary sharply with system characteristics — a finding that holds for satellite imagery as much as for drones, which are more precise at the scale of a single plant (see the study on Google Scholar).
Price and response time in 2026
After a loss event, turnaround matters as much as price: most providers offer a response within 48 to 72 hours for the photo pass, with thermography following as soon as the first window of sufficient irradiance opens. Orders of magnitude observed in France in 2026 (excl. VAT):
- RGB photo pass only, emergency record: €150 to €350 per megawatt-peak.
- Photo + thermography pass, module-by-module report with geolocated anomalies: €400 to €800 per megawatt-peak.
- Comparison with an earlier thermal map, if one exists: additional processing fee, €200 to €500 depending on plant size.
- Photovoltaic roof of an industrial or farm building: €400 to €800 per half-day, depending on access and roof-structure complexity.
Regulation-wise, the mission falls under the same framework as periodic thermography — open category A3 for a fenced site kept away from third parties, subject to checking the area on the Géoportail map — and requires a provider covered by up-to-date professional third-party liability insurance. For an operator or technical manager (O&M) facing a loss event, request a quote stating the installed capacity, the date of the weather event, and whether an earlier thermal map is available for comparison.