PerformanceUp to date · Jan 15, 2026
Round-Trip Efficiency
The percentage of energy put into a battery that can be retrieved. Typical lithium-ion batteries have 90-95% round-trip efficiency — meaning 5-10% is lost as heat during charge/discharge.
Why It Matters
A battery with 90% round-trip efficiency loses 10% of every kWh stored. Over a year with daily cycling, this adds up to significant energy loss that should be factored into system sizing.
Related Terms
Battery Storage
A system that stores excess solar energy for use when the sun isn't shining, providing backup power during outages.
Cycle Life
The number of complete charge-discharge cycles a battery can perform before its capacity drops below a specified threshold (typically 70-80% of original capacity).