SMA SUNNY ISLAND 6.0H - Stopping the System; Switching off the Sunny Island

3 Functions and Design
SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-1018
The SunnyIsland generator management allows for uninterruptible connection of the stand-alone grid to the generator
and uninterruptible isolation from the generator. The generator management controls the generator via a start and stop
signal. A generator current control ensures that the generator always remains at the optimum operating point. The
generator management allows the use of generators that have a low output power in proportion to the nominal load
(see technical document "Sunny Island Generator - Whitepaper" at www.SMA-Solar.com)
Load Control
The load control enables control of the AC sources in stand-alone grids, control of a generator, and the specific
disconnection of loads.
The AC sources in the off-grid system are limited in their power output by the stand-alone grid frequency. In case of
excess energy, the load control system increases the power frequency of the stand-alone grid. This limits the output
power of the PV inverters, for example.
If there is not enough energy available for all loads or the battery is to be preserved, load control can request energy
from a generator by means of the generator management. The generator management starts the generator and the off-
grid system is supplied with sufficient energy.
If no generator is present in the off-grid system or the energy is not sufficient despite the generator being available,
load control turns the loads off using load shedding. All loads are shed simultaneously with one-stage load shedding.
A load shedding contactor sheds the noncritical loads during the first stage with two-stage load shedding. The
remaining loads are shed during the second stage only when the state of charge declines further. This can further
increase the availability of the stand-alone grid for critical loads.
3.3.2 Off-Grid System Requirements
Utility grid connection via Grid-Connect-Box
The utility grid can support or assume the function of a PV array in, for example, areas with a weak grid structure.
To connect the utility grid and generator in parallel to an off-grid system, a Grid-Connect-Box must be installed.
The Grid-Connect-Box may be used only in areas where VDE-AR-N4105 application guide does not apply.
The Grid-Connect-Box is always delivered with all-pole disconnection. If, during a grid failure, the technical
connection requirements of the grid operator or the locally applicable standards and directives prohibit
disconnection of the neutral conductor, you must deactivate the all-pole disconnection in the Grid-Connect-Box
(see operating manual of the Grid-Connect-Box).
Utility grid connection to the Multicluster-Box
If the utility grid is directly connected to the Multicluster-Box, no generator is to be installed in the multicluster
system. When connecting the utility grid to the Multicluster-Box, the Multicluster-Box terminal provided for the
generator must be used (see operating manual of the Multicluster-Box).
The installer bears sole responsibility for the grounding configuration and the grid disconnection required for
instances of grid failure. Grounding and grid disconnection must be carried out in accordance with local
standards and directives and approved by the grid operator.
3.3.3 Optional Devices and Functions
The following devices can be used optionally in an off-grid system:
Component Description
External load-shedding contactor Contactor controlled by the SunnyIsland for isolation of loads in the multicluster
system during two-level load shedding.
SMA Cluster Controller Remote monitoring and system configuration of the off-grid system