Round-trip Efficiency
PerformanceAlso known as: RTE, System Efficiency
Round-trip efficiency (RTE) measures how much energy is returned by a battery system compared to the energy used to charge it. An RTE of 90% means that for every 100 MWh charged, 90 MWh is available on discharge — the remaining 10 MWh is lost as heat in the cells, PCS, and auxiliaries.
RTE is measured at the AC level (AC-to-AC) for the complete system, including PCS conversion losses, auxiliary power consumption (cooling, controls), and battery losses. It is a key performance metric for BESS economics — higher RTE means more energy to sell and better project returns.