Work out battery round trip efficiency instantly with clear inputs, formula shown and shareable results.
Round-trip efficiency is energy out divided by energy in over a full charge and discharge cycle, measured at the same point in the system. Lithium systems achieve 85-95% at the DC terminals but 82-90% at the AC connection once inverter and auxiliary losses are included, and auxiliaries such as cooling matter at high ambient temperature.
Round-trip efficiency
RTE % = energy discharged x 100 / energy charged
Annual loss
Annual loss = loss per cycle x cycles per year
At the point of connection that matters commercially, normally AC. DC-side figures exclude inverter and transformer losses and auxiliary consumption, so they flatter the system by 3-8 points.
Yes. Higher charge and discharge rates raise ohmic losses, so round-trip efficiency falls by several points at 1C compared with 0.25C.