Inverter power derating

The inverter delivers less power than it should, or switches off, to protect its internal parts from overheating. Inverters do not always show a derating or power reduction message, so check their behaviour with power versus irradiance curves. Temperature derating usually starts above a set ambient or internal temperature, and output then drops along a fixed curve. Overheating can come from poor installation, fan failure, dust blocking heat dissipation or wrong inverter programming. Derating also happens when the grid voltage is below the rated output voltage, when the DC input voltage is outside the MPPT range, or when a user command asks for it. To find the cause, compare the logged inverter temperature, the grid voltage and the DC input voltage with the times the power was reduced. Check first that all external fans are running and that the ambient temperature is within the normal operating range.

<!-- review notes

• sentence 3: support check: partial - The 45°C onset and linear derating curve are stated, but only for specific models; a general claim of a 'fixed curve' and internal temperature thresholds is not stated.
• sentence 6: support check: partial - Passages describe the derating conditions and that inverter temperature may be logged, but none explicitly recommend comparing logged temperature, grid and DC voltage against derating times.
• sentence 7: support check: partial - Both checks are in the troubleshooting text, but the passage doesn't say they should be done 'first'. -->