About the Shutdown Impact Calculator
Shutdown impact analysis quantifies the revenue and energy loss caused by planned or unplanned shutdowns of a solar plant or BESS — including grid outages, maintenance windows, protection trips, and curtailment — to support O&M scheduling, OEM coordination, and PPA performance guarantee management.
How to calculate it
- 1For each shutdown event, record: start time, end time, plant capacity affected (full vs partial), and cause.
- 2Energy loss = plant capacity × average irradiance during shutdown × performance ratio × shutdown duration.
- 3Revenue loss = energy loss × applicable tariff (PPA rate for utility; avoided grid cost + export rate for C&I net metering).
- 4Classify by cause: grid curtailment (DISCOM-caused, may have compensation provisions), maintenance (planned, minimised by scheduling off-peak hours), and unplanned trips (OEM warranty or O&M contractor liability).
- 5Annual availability impact: downtime hours ÷ 8,760 × 100 = % unavailability. Target: < 1% for well-maintained utility-scale plants.
Worked example
A 1 MWp plant suffers 3 grid curtailment events (total 12 hours, 10 AM–1 PM), 1 inverter repair (8 hours at 2 PM), and 2 planned maintenance windows (4 hours each, early morning). Curtailment loss: 1 MW × 12 h × 0.7 avg GHI factor × 0.8 PR = 6.72 MWh. Revenue: 6.72 × ₹4.50 = ₹30,240. Annual availability: (8,760 − 28) ÷ 8,760 = 99.7%.
What you can calculate
- Revenue loss
- Penalty estimate
- Maintenance window
- Risk
Frequently asked questions
Can solar plant owners claim compensation for DISCOM curtailment in India?
Under CERC's RE curtailment regulations, renewable energy plants have 'must-run' status — DISCOMs cannot curtail them without paying compensation (deemed generation) unless grid security requires it. In practice, enforcement is weak and many curtailment events go uncompensated due to poor SCADA data logging and disputes about the cause. Plants with good data logging (timestamps, MW output, SCADA integration) are better positioned to claim deemed generation compensation.
What is the best time to schedule planned maintenance for a solar plant?
Schedule planned maintenance during: (1) early morning (5–8 AM) when irradiance is low and loss per hour is minimal; (2) monsoon season for work that requires inverter isolation (low-generation period); (3) night-time for work that does not require the plant to be de-energised. Avoid scheduling shutdowns during peak summer months (March–May) when the irradiance and revenue per hour is highest. For C&I plants: avoid peak ToU windows (6–10 PM in most DISCOMs).
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