Thar Solar Park Thermal Audit

The problem

The park had been commissioned in 2021 and was running roughly 4% below its expected P50 yield. SCADA could see the shortfall at inverter level but could not localise it, and the O&M contractor's hand-held thermal programme was sampling under 2% of modules a year.

With around 268,000 modules across 620 acres of Thar desert, walking the asset was not a realistic answer. Site temperatures in the diagnostic window sat between 44 and 47 °C.

What we did

Vikram's team flew automated grids at a fixed 55 m AGL for a consistent 3 cm thermal GSD, strictly inside the 11:00–14:30 window with irradiance logged above 700 W/m² throughout. Anything outside that band was discarded rather than reported.

Before flying we ingested the SCADA string map and the module datasheets, so every finding could be reported in the client's own table–row–position naming rather than in our coordinates. Six aircraft flew in parallel with hot-swap battery stations at the block boundaries.

Every flagged anomaly was reviewed by hand against reflection and soiling artefacts before it entered the register. Roughly 12% of software-flagged candidates were rejected at that stage.

The outcome

1,847 modules were confirmed defective – 0.69% of the installed base. The breakdown: 912 single-cell hotspots, 476 bypass-diode failures, 301 PID-affected modules concentrated in four blocks at the western edge, and 158 complete module outages.

Two entire strings were found disconnected at the combiner, having never been commissioned correctly – neither had ever shown as a fault in SCADA. Estimated recoverable generation across all findings was ₹2.9 crore per year against an audit cost under ₹7 lakh.

“We had 900 underperforming strings somewhere in the park and no idea where. The audit found every one of them in two days of flying and gave us a report our O&M team could work straight off.”

Sandeep Chauhan, GM Operations, Bharat Solar Energy