Round-Trip Efficiency — the fraction of energy recovered after a full charge-discharge cycle. LFP lithium batteries typically achieve 85–92%. Losses occur in the inverter and battery chemistry.
Round-Trip Efficiency (RTE) is the fraction of energy a battery gets back out after putting energy in through a full charge-and-discharge cycle. If a unit draws 100 MWh to charge and can then discharge 88 MWh, its round-trip efficiency is 88%. The lost energy is dissipated as heat in the inverter and the battery chemistry itself; lithium iron phosphate (LFP) systems, which dominate new NEM builds, typically achieve 85–92%.
RTE matters for economics because it sets a floor on the price spread a battery needs to arbitrage profitably: at 85% efficiency, a unit must sell for at least ~1.18 times what it paid just to break even on the energy round trip, before any other cost. It also matters for NEMPulse's data: where AEMO has not yet published a unit's reported state of charge, NEMPulse integrates SOC from dispatch MW using an assumed round-trip efficiency of about 85% (0.92 charging × 0.92 discharging), shown as a dotted line to mark it as inferred rather than measured.
Related terms: SOCEnergy Arbitrage
See also: Battery detail pages
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