₹12.3 Lakhs in Losses Due to Deferred Maintenance – 5 MW Rooftop Solar Plant

Site Profile

• Location: Western India – Industrial Manufacturing Unit

• Plant Size: 5 MW Rooftop Solar

• Operational Age: 4.5 years

• Previous Maintenance Practice: Basic in-house cleaning, no predictive diagnostics, no formal asset testing, missing documentation

Issues Identified During Initial Assessment

1. Severe Module Soiling – Over 40% of Array

• Accumulated dirt on 40% of the modules with no cleaning cycle record for over 4 months

• Soiling Index >7%, exceeding recommended limits for performance

• Loss of energy output calculated between 5.6–6.5%

• Direct generation loss: ₹4.5 Lakhs/year

2. Thermal Derating in Inverters

• Inverters observed to be running at ~80% efficiency during peak hours

• Root cause: blocked air passages, non-functional internal cooling fans, and zero thermal inspections for 2+ years

• Thermal imaging revealed internal hotspots >75°C

• Estimated energy loss: ₹3.2 Lakhs/year

3. Fire Safety System Non-Compliance

• No fire extinguisher refill or inspection in 2 years

• Missing rooftop isolator signage and evacuation SOPs

• High insurance and operational risk; could have failed safety audits

• Estimated risk value: ₹2–₹2.5 Lakhs in potential non-compliance costs

4. Earthing System Failure

• Earth loop impedance measured at >9 ohms at multiple pits

• Breaks in continuity due to corroded connections and dried-out backfill

• Surge-related voltage drop incident nearly led to a total inverter shutdown during monsoon

• Estimated avoided loss: ₹2 Lakhs

5. DC Cable Fault Location Delays – The Hidden Downtime

• During a sudden voltage drop, a fault occurred in one DC string cable

• Due to the absence of updated as-built drawings, it took 3 full days to locate the fault using trial-and-error and handheld thermal sensors

• After completion of system diagnostics and preparation of cable layout drawings during the audit, a similar fault occurred 6 weeks later

• This time, the team identified the fault within 3 hours and completed same-day repair

• Documented outcome:

  • Reduced response time from 3 days to 3 hours

  • Avoided generation loss of ₹75,000

  • Drastically reduced manpower and resource wastage

Solutions Implemented

✅ Deep cleaning cycle using manual and robotic methods

✅ Inverter thermal management restored (fan replacement, airflow correction)

✅ Fire extinguishers refilled, SOPs and safety signage installed

✅ Earth pit repair and enhancement with new rods and backfill compounds

✅ IV Curve Testing, Thermal Imaging, Relay Testing, Continuity & Earth Resistance Checks

✅ Complete as-built electrical documentation including cable paths, inverter mapping, and asset condition tagging

Key Takeaways

• Deferred maintenance = silent revenue leakage. This plant was functional, but not financially efficient.

• Thermal derating, soiling, and lack of system visibility created multi-layered inefficiencies.

• Accurate as-built documentation significantly reduced downtime and improved response efficiency during real faults.

• A one-time diagnostic saved recurring yearly losses, improved compliance, and increased system life.

📩 Ready for Action?

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