C-rate

The C-rate expresses how fast the battery storage can be charged or discharged relative to its capacity. 0.5C means that the full capacity can be moved in 2 hours (e.g. a 1 MWh storage system at 500 kW of power); 1C = 1 hour.

For industrial HUPX arbitrage, 0.5C is usually sufficient — one or two cycles a day do not require fast charging. A higher C-rate requires more expensive hardware and degrades the cells faster, so it is only justified if the application (e.g. fast peak control) demands it.

The ratio of power (kW) to capacity (kWh) is the C-rate — the key sizing parameter.