Solar photovoltaic systems are a growing feature on commercial and leisure premises, and a golf club in Hampshire had two roof-mounted arrays installed across its main clubhouse and an ancillary building. With the system recently commissioned, the owner wanted independent verification that both arrays were performing as intended and free of the early-life faults that can develop unseen. Drone Media Imaging was engaged to carry out a combined thermographic and electrical inspection to the relevant international standards.

A solar PV thermographic inspection under IEC 62446-3:2017 is a qualitative survey that reads the thermal behaviour of every module while the array is working under load. Cells that are faulty, shaded or electrically compromised dissipate energy as heat rather than converting it to electricity, and that heat shows as a distinct thermal signature. Capturing the arrays from the air allows the full module population to be surveyed quickly and safely, without foot traffic on the roof, and every signature is then validated against a clean reference module of comparable orientation within the same thermogram to separate genuine faults from harmless reflections.

The inspection was delivered by Drone Media Imaging, a trading name of VisualChaos Studios Ltd, and analysed and signed off by our Level 3 Master Thermographer. Pairing the aerial thermal survey with electrical string testing gives a fuller picture than either method alone, cross-checking what the thermal image suggests against measured electrical performance, and it is the approach we recommend for any commercial rooftop array where access and architecture allow.

Thermography is environmentally dependent, so timing and conditions matter. The survey was carried out under clear skies with solar irradiance above 900 watts per square metre and light winds, comfortably within the operating conditions IEC 62446-3 sets for a valid inspection. Ambient temperature, humidity, wind and irradiance were all logged on site so the results could be interpreted against the exact conditions on the day.

Every module across both roofs was captured with a survey-grade drone-mounted thermal sensor, flown to a consistent height and angle to keep the imagery uniform. Each thermogram was reviewed against a clean reference module within the same image, and any elevated signature was measured and classified. The electrical stage used IEC-compliant test instruments to check the accessible array, verifying insulation resistance and tracing the full current-voltage curve of the string to confirm its performance against expected values.

One array used module-level power optimisers, an architecture that clamps the string voltage to a safe level when the inverter is isolated. Conventional string testing cannot be performed meaningfully on that architecture, so the standard provides for a modified regime, and earth continuity was verified in its place. This is a defined provision of the standard, not a limitation of the inspection.

The inspection covered:

• Full aerial thermographic survey of both rooftop arrays, every module, to IEC 62446-3:2017.
• Electrical string testing of the accessible array to IEC 62446-1, insulation resistance and current-voltage performance.
• Earth continuity verification on the optimiser-based array, in line with the standard’s modified regime.
• On-site logging of environmental conditions and radiometric set-up.

Not included: inverter diagnostics, switchboard or on-roof electrical work, and any remedial activity, all of which sit outside the scope of a survey, analysis and reporting engagement.