Self-discharge

The battery has always a loss of stored energy, due to a permanent self-discharge current. Its value is sometimes appearing on the 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.

The self-discharge is dependent on the temperature. PVsyst proposes a temperature profile, which was established for Lead-acid batteries according to our early discussions with a battery manufacturer. The self-discharge is stable at low temperatures, and increases above 20°C.

In absence of data for Li-ion batteries, we apply the same temperature correction in our database. However this really represents a very little contribution to the battery losses.