Power Derating refers to the reduction in the power output that a battery energy storage system (BESS) can deliver compared to its nominal (rated) capacity. This reduction may be deliberate or required due to factors such as environmental conditions, operational constraints, or design limitations. As a result, the system's actual power availability may be lower than expected, affecting its performance, reliability, and ability to meet grid demands. The effect of derating is often represented using a derating curve, which illustrates how power output declines as these influencing variables increase. To determine the derated power output, the rated power is adjusted by a derating factor. For example, if a battery system is rated at 100 kW and experiences a 15% derating, its actual usable output would be 85 kW.

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