Methods: Battery duration and usable energy
calc.storage.basics · Version 0.1.0
Method
Duration is energy ÷ power; C-rate is power ÷ energy. Depth of discharge limits the energy delivered, and round-trip efficiency is a loss taken on charging, so charging energy is delivered energy ÷ efficiency. The same convention holds in the workbench's battery screen.
Assumptions
- Rated energy is the battery's nameplate energy at its rated power; real duration falls at high power and low temperature.
- Depth of discharge and round-trip efficiency are the values entered; degradation is not modeled.
Sources
- NLR, Annual Technology Baseline (ATB): Utility-Scale Battery Storage, 2025, Definitions of power, energy, duration, and round-trip efficiency
Worked examples
| Example | Independent source | Tolerance | Last result |
|---|---|---|---|
| 100 MW / 400 MWh dispatching at 75 MW | calc/storage-and-cost spec, scenarios "Partial-power dispatch" and "Usable energy" | ±0.005, ±0.00005, ±0.05, ±0.05 | Passed on Oct 31, 2026 |
Known differences from reference engines
None recorded.
Cite this tool
Battery duration and usable energy, version 0.1.0. gridprims. https://gridprims.com/tools/calc/storage/basics/