From a grid perspective, the output (delivery) is typically more important than total capacity - because it's acting sort of like a power plant. Power plants d

From a grid perspective, the output (delivery) is typically more important than total capacity - because it's acting sort of like a power plant. Power plants don't have capacity, really. So you hear about the output GW, not the capacity GWh. For battery plants, they might mention duration (4 - 6 hours), which makes converting to capacity in terms of GWh trivial.