# Derating

The automatic reduction of an inverter's output power to protect its internal components, most commonly triggered by high temperature but also by high grid voltage or by an out-of-range input. The unit keeps running at reduced capacity instead of shutting down.

Source: https://inverterdata.com/en/glossary/derating/
Site: InverterData (inverterdata.com) — open technical specification database
Last updated: 2026-08-24
License: free to quote with attribution to inverterdata.com

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Thermal derating is the usual case: once ambient temperature climbs past the manufacturer's threshold, output falls progressively, and it does so on exactly the hot, clear afternoons when the array is producing hardest. Mounting on a shaded, ventilated north-facing wall — south-facing in the southern hemisphere — and respecting the specified clearances often recovers more annual energy than choosing a nominally more efficient model. Grid-voltage derating is the other frequent cause and points at a different problem: a long or undersized AC cable run pushing the voltage at the inverter terminals towards its upper limit.