> What's a "GW of battery storage capacity"?

This is the maximum amount of power it can dispatch. I think they use it intentionally so they can compare it to other generation sources.

For example this spreadsheet [1], with data for 2023, contains figures for "power capacity megawatts" and "energy capacity megawatthours".

1. https://www.eia.gov/analysis/studies/electricity/batterystor...

This source has some useful stats on duration: https://seia.org/research-resources/energy-storage-market-ou...

> In Q2 2026, battery energy stationary storage (BESS) installations reached 20.2 GWh

> total module manufacturing capacity to over 100 GWh.

> Storage Deployed in 2025: 57.6 GWh