Changing the Battery Protection Mode in Off-Grid Systems

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

Function of the battery protection mode:

The battery protection mode protects the battery.

If the state of charge (SOC) of the battery falls below the thresholds, battery protection mode is activated. In battery protection mode, the Sunny Island switches to energy-saving mode or switches itself off. The battery protection mode has three levels. One state of charge threshold can be set for each level. Levels 1 and 2 of the battery protection mode have specific start and end times and are therefore dependent on the time of day ( > Setting Time-Dependent Functions).

• Level 1

  If the state of charge falls below the threshold for level 1, the Sunny Island switches to energy-saving mode between the start time and end time. This way you can specify preferred times for the Sunny Island to be switched off if an energy deficit occurs.

• Level 2

  If the SOC drops below the threshold for level 2, the Sunny Island switches to energy-saving mode. Use the start time and end time to define the time window in which no energy is anticipated from AC sources. Outside this time window, the Sunny Island starts up every two hours to charge the battery. If no energy is available to charge the battery, the Sunny Island remains on energy-saving mode.

  This means that, for example, in stand-alone grids with PV inverters, you can specify that the Sunny Island does not start up at night, preventing it from consuming energy from the battery.

• Level 3

  If the state of charge falls below the threshold for level 3, the Sunny Island switches itself off. This protects the battery against deep discharge and severe damage. To charge the battery again, the Sunny Island must be switched on and started manually.

At all three levels, the Sunny Island will only switch to energy-saving mode or switch itself off if no charging current has flowed in the battery for at least five minutes.

Recharging the battery with an external energy source:

In levels 1 and 2 of battery protection mode, you can charge the battery at any time with an external energy source. If a voltage is present on connection AC2, the Sunny Island exits the energy-saving mode.

If the Sunny Island has switched to level 3 of battery protection mode by itself, you must charge the battery in emergency charge mode (see the Sunny Island inverter operating manual).

Time settings:

The start time and the end time can be configured for battery protection mode levels 1 and 2.

If the state of charge falls below the threshold for level 1, the Sunny Island switches to energy-saving mode between the start time and end time.

If the state of charge falls below the threshold for level 2, the Sunny Island switches to energy-saving mode between the start time and end time. The Sunny Island attempts to charge the battery in the remaining time.

Procedure: