Understanding Battery Round-Trip Efficiency
How we calculate. RTE % = energy out ÷ energy in × 100. The form uses the same arithmetic as the worked examples on this page. See our methodology and accuracy policy.
Real-world scenario: A typical Battery Round-Trip Efficiency case uses discharge (mwh) 900 and charge (mwh) 1000. Enter the same figures below to reproduce the worked path.
What is Battery Round-Trip Efficiency?
A storage performance KPI for BESS. Distinct from heat-rate thermal efficiency and parasitic (station service) load %.
- Same AC or DC basis for both
- Charge = energy into the battery
- Exclude idle parasitic unless labeled in
The Formula
Worked Example
Common Use Cases
- BESS warranties: RTE checks
- Asset reviews: cycle efficiency
- Dispatch models: loss assumptions
Pro Tips
- State AC vs DC metering
- Align charge/discharge over same cycles
- Pair with parasitic load for plant losses
Limitations: Battery Round-Trip Efficiency results are educational energy and utilities planning aids—not engineering, grid-operations, or investment advice. Confirm definitions with your ISO/RTO, plant, and regulatory reporting standards.
FAQ
Same as heat-rate efficiency?
No. Heat-rate efficiency converts Btu/kWh to thermal %. RTE is battery discharge÷charge energy.
What if charge MWh is 0?
RTE is undefined—enter positive charge energy.
Authoritative References
For power system and plant performance concepts, consult: