Self-discharge

Batteries always lose stored energy due to permanent self-discharge current. This value sometimes appears in datasheets.

The default value proposed by PVsyst is 4% for Lead-Acid batteries, and 3% for Li-Ion. This default is specified in the advanced parameters.

Self-discharge is temperature-dependent. PVsyst uses a temperature profile established for lead-acid batteries from discussions with a manufacturer. Self-discharge is stable at low temperatures and increases above 20°C.

Lacking li-ion battery data, we apply the same temperature correction in our database. However, this contributes minimally to overall battery losses.