Solar MD SS4143-11, Installation Manual

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3. Device Connection
3.1. SMA
3.1.1. General Information
3.1.1.1. Protection of the battery system in Sunny Island:
The operation of the overall system and the protection of the battery
system in Sunny Island are based on the SOC of the battery. The battery
preservation mode prevents the battery from being deeply discharged as far as
possible when the energy supply is low, thus, preventing a total system failure
as well as damage to the battery. Note that the Parameters used for the
protection of the battery system are depending on the application and resultant
operational mode of inverter. Nevertheless, some similarities exist, so that the
general description of levels is valid for all applications. Detailed explanation
can be found in [1], [2].
Battery protection modes Description:
● Level 1 The first level is used to prevent further active discharge of the
battery and switch the Sunny Island into standby mode at times when the
energy is not necessarily required. The corresponding parameters which are
used for the Level 1 protection are defined depending on the application.
Detailed information can be found in [2].
● Level 2 The second level of the battery preservation mode ensures
that the Sunny Island is started regularly every two hours only in the time period
during which energy supply (for example PV Energy) is expected. In case of
grid-connected application recharging from grid is also initiated. The
corresponding parameters which are used for the Level 2 protection are defined
depending on the application. Detailed information can be found in [2].
● Level 3 The third level ensures that the battery is protected from deep
discharge and thus against damage. In this case, the Sunny Island is switched
off completely. The re-start of the system is described in [2]. The corresponding
parameters which
At all three levels, the Sunny Island is stopped only if no battery
charging current flows within 5 minutes (limit is at least 3 A charging current) –
these values are configurable in expert mode for off-grid application only – refer
to [1], [2].
Note that a re-start/recharging of the system is only possible if the
charging current is available (grid) and the battery voltage is higher than a
lower voltage limit (see technical data).
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