Abrupt production drop

An abrupt production drop is a sudden fall in plant output. After a snowfall, it can happen even though the plant is available and the irradiance sensors still show usable sunlight. In snow accumulation yield losses, snow on the module surface blocks the light, so covered modules produce no current. The drop comes suddenly after the snow, and recovery is usually gradual as the snow melts or slides off. During partial clearing, current can be uneven across strings and substrings, so the loss may not match how much snow you can see. Check timestamped weather data first: precipitation type, snowfall, snow depth, ambient temperature, wind and irradiance. Line these up with SCADA production residuals and with camera, drone or field observations of snow on the modules. Book snow cover loss separately from downtime. If snow is present but the system is not producing at all, treat it as downtime, not snow loss. If output recovers more slowly than the energy model's snow-loss assumptions predict, the snow-loss factor may need revising, even when the equipment is working normally. Monitoring should also confirm that the drop comes from a fault or a known cause, not from a cloudy day. Any drop below the expected performance ratio should lead to closer checks by maintenance staff.

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• sentence 2: support check: partial - Abrupt drop and gradual melt/slide-off are stated, but 'produce no current' is overstated given partial coverage and 'usually' gradual recovery is not exactly stated.
• sentence 5: support check: partial - Passage says snow losses are distinguished from downtime when snow present and system not producing, but doesn't explicitly say to book it as downtime rather than snow loss.
• sentence 7: support check: partial - Passages say algorithms ascertain drop is from a fault not a cloudy day, and a drop in expected PR triggers closer monitoring by maintenance staff, but 'should confirm' as monitoring requirement is a slight stretch. -->