Round-trip efficiency
By Priya Nair · Last reviewed The fraction of energy that survives the journey into and back out of a battery, including conversion losses in both directions. Marketing figures quote ideal conditions; independent measurements of balcony storage under real household loads land meaningfully lower — roughly 70-85%, with low-power night-time discharge the worst case.
Why it matters
Round-trip losses are the quiet tax on every battery payback claim: a system that stores 1 kWh and returns 0.75 changes the economics by a quarter. Independent German lab and owner measurements — not app dashboards, which have been caught displaying impossible figures — are the numbers to trust.