Fronius Energy Package, Operating Instructions Manual, Page: 31 / 148

Calibration charging for the Fronius Solar Battery
Benefits of cal-
ibration charging Natural differences in the individual cell capacities and the small amount of self
discharge that occurs in all batteries cause the cell voltages to diverge. This
makes the SOC value less accurate, which affects the operation. If no steps are
taken, the battery will become damaged.
Periodic calibration charging brings all cells of the battery to the same state of
charge, and calibrates the SOC value. This ensures a longer service life of the
battery cells.
General Determining the exact state of charge (SOC) of the battery is important for oper-
ation management. To ensure this happens, the battery must regularly be
charged to 100%. This allows the SOC value to be calibrated.
Fronius Solar Battery:
Calibration charging occurs automatically during operation after several charge
and discharge cycles. When calibration charging is carried out depends on two
crucial factors:
- Average state of charge
- Energy throughput of the battery
As these factors are extremely weather dependent, the time of a calibration
charge can vary depending on the time of year.
The following description of calibration charging is valid from version 1.4.1-12 of
the Fronius system monitoring software.
Conditions for
starting the cal-
ibration charge
(Fronius Solar
Battery) One charge and discharge cycle of the Fronius Solar Battery corresponds to an
energy throughput of 48 Ah per battery module. Calibration charging occurs cyc-
lically according to the following conditions:
- After 3 full charge and discharge cycles and a SOC of 80%
- After 5 full charge and discharge cycles and a SOC of 50%
- After 7 full charge and discharge cycles, independent of the SOC
For newly installed systems and for module replacement or expansion, a calibra-
tion charge is started automatically after 30 minutes.
Calibration char-
ging procedure
(Fronius Solar
Battery) Calibration charging primarily occurs with the entire PV power. If insufficient PV
energy is available, energy is drawn from the public grid. This is also the case
even if the "Battery charging from DNO grid" function is deactivated, as this is a
critical requirement.
The SOC is calculated per battery module. For this reason, each battery module
must reach a SOC of 100%.
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