Commercial solar in autumn: seasonal drop or a fault?
As the days shorten and the angle of the sun changes, commercial solar PV systems naturally produce less energy than during the peak summer months. However, distinguishing between a seasonal performance drop and an underlying technical fault is critical for protecting your investment. Commercial solar in autumn often produces less electricity as daylight hours shorten, but a sudden or unexplained drop deserves further investigatio
Commercial solar in autumn: start with a fair comparison
Compare the same dates across your monitoring platform and generation meter. Record units and missing days. Compare with the monthly design forecast, recognising that forecasts are not measurements and weather varies. Allow for orientation, shading and capacity differences.
Check the data
A blank app chart can reflect an internet or logger problem. Check when the portal last updated and recent meter generation without opening equipment or changing protection settings. Higher bills can reflect consumption or tariff changes. Export is not total generation; power in kW differs from energy in kWh.
Keep a fault record
Should efficiency decline, track specific indicators immediately. Log the precise moment output waned and identify any environmental stressors like gale-force winds or intense fall downpours. Maintaining this data aids technical experts in isolating bugs quickly during official facility inspections.
Energy Saving Trust: solar panel cleaning and maintenance
Sources checked 16 October 2026.
Cleaning and safe access
Roof access and electrical work must be assessed and planned by competent people. Cleaning decisions should consider soiling, manufacturer guidance and safe access. Do not access a roof or touch cabling based on this checklist.
Arrange a performance review
CEC can review generation data and agree any further investigation required. Outcomes depend on the cause.