SMA SI 3.0-11 Quick Reference Guide V.3.0 - Manual (Page 7)

SMA Solar Technology AG 2 Safety
Installation - Quick Reference Guide Ersatzstrom-IS-en-30 7
2 Safety
2.1 Intended Use
In the event of grid failure, a battery backup system with Sunny Island supplies loads with energy and a grid-tie PV system
with voltage. In the event of grid failure, an automatic transfer switch disconnects the battery backup grid from the utility
grid. After disconnection, the loads and the PV system have no supply for approximately five seconds, until the battery
backup system can provide active and reactive power once more. The battery backup system supplies the loads and the
PV system can synchronize with the battery backup grid and feed in.
The battery backup system should only be used in countries for which it is licensed or for which it is released by
SMA Solar Technology AG and the grid operator. To fulfill the technical connection requirements of the grid operator
and the local standards and directives, you must select one of the following basic structures:
• Battery backup system with all-pole disconnection
In the event of grid failure, a tie switch disconnects all line conductors and the neutral conductor from the utility grid.
The tie switch is designed with built-in redundancy. If the technical connection requirements of the grid operator or
the local standards and directives call for or allow all-pole disconnection, you must install this basic structure. You
must install all-pole disconnection in the following countries:
– Belgium
– Denmark
– Germany
– France
– Austria
– Switzerland
• Battery backup system without all-pole disconnection
In the event of grid failure, a tie switch disconnects all line conductors from the utility grid. The neutral conductor of
the battery backup grid remains permanently connected to the utility grid. If the technical connection requirements
of the grid operator or the local standards and directives prohibit disconnection of the neutral conductor, you must
install this basic structure. In Australia, you must install a battery backup system without all-pole disconnection.
Each basic structure can be designed either as a three-phase battery backup grid or as a single-phase battery backup
grid. Single-phase battery backup grids can be connected to three-phase utility grids.
In a three-phase battery backup system, in the event of grid failure, three Sunny Island inverters supply all line conductors
with the corresponding line conductor. The three Sunny Island inverters are connected in parallel on the DC side and form
one cluster. Only Sunny Island inverters of the same device type may be installed in a cluster. In a three-phase battery
backup system, both single-phase and three-phase PV inverters can be connected. Multiple clusters must not be connected
together.
In a single-phase battery backup system, in the event of grid failure, one Sunny Island supplies the battery backup grid.
A grid failure is only recognized at the line conductor which is connected to the Sunny Island. In the event of grid failure,
only single-phase PV inverters can feed in to a single-phase battery backup grid. A phase coupling, in the event of grid
failure, enables combination of the line conductors to a single-phase distribution grid. With phase coupling, all the loads
in the battery backup grid must be single-phase. No more than one Sunny Island may be connected in a single-phase
battery backup system.
A PV system can be connected in the battery backup grid. The PV system must be suitable for use in battery backup
systems (see the Planning Guidelines "SMA Flexible Storage System with Battery Backup Function" at
www.SMA-Solar.com). The power of the PV system must be appropriate for the system (see Section 3.2 "System
Information", page 12).
The automatic transfer switch is not a distribution board for the loads or the PV system. The loads and the PV system must
be secured with protective devices in accordance with the local standards and directives. Grid-forming voltage sources
(e.g., generators) must not be connected.