Energy Storage
BESS Sizing Guide: MW Power vs. MWh Energy Capacity
Understand how utility-scale battery energy storage systems (BESS) are sized, duration ratios, and efficiency losses.
David Rodriguez, Storage Architect
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Battery Energy Storage Systems (BESS) Explained
Modern grid batteries are described by two distinct metrics: MW (Power rating) and MWh (Energy capacity).
The C-Rate and Duration
A 100 MW / 400 MWh battery system has a 4-hour discharge duration at maximum output:
Duration (Hours) = Capacity (MWh) ÷ Power (MW) = 400 MWh ÷ 100 MW = 4 hoursThese systems are crucial for time-shifting solar energy from midday peaks to evening high-demand periods.