Setting Utilization of Excess Energy in Off-Grid Systems


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Switching-on time and switching-off time for utilization of excess energy during constant voltage phase

The Sunny Island controls the utilization of excess energy during the constant voltage phase depending on the cell voltage of the battery. During the constant voltage phase, the battery is charged with a constant charging voltage. When the setpoint of the cell voltage in the constant voltage phase is reached, the multifunction relay is activated. The multifunction relay remains in this position for the minimum time specified (Minimum time for the use of excess energy). If the cell voltage differs by more than a specified value (Voltage difference for the use of excess energy) from the setpoint of the cell voltage after the minimum time, the multifunction relay is deactivated. The setpoint of the cell voltage depends on the charging process during the constant voltage phase.

Charging Process

Parameters

Default value

Boost charge

Battery > Charge > Cell charge nominal voltage for boost charge

2.40 V

Full charge

Battery > Charge > Cell charge nominal voltage for full charging

2.45 V

Equalization charge

Battery > Charge > Cell charge nominal voltage for equalization charge

2.45 V

The basic procedure for changing operating parameters is explained in another section Changing Operating Parameters).

Procedure:

  1. Set the parameter Minimum time for the use of excess energy to the minimum time that the multifunction relay remains activated.
  2. Set the parameter Voltage difference for the use of excess energy to the voltage difference relative to the setpoint of the cell voltage during the constant voltage phase.
  3. Recording of the measured values of the cell voltage reacts to changes with time-lag

    The Sunny Island calculates the cell voltage from the measured battery voltage. The Sunny Island calculates an average from the measured values of the battery voltage. As a result of the calculation of an average, the cell voltage that is recorded reacts to changes with a time-lag.

  4. Ensure that the multifunction relay used for control is set to Control of add. loads Setting the Functions of the Multifunction Relays).