SMA Off-Grid Systems - Manual (Page 16)

3 Information on Off-Grid Systems and System Description SMA Solar Technology AG
16 Off-Grid-IS-en-30 Installation - Quick Reference Guide
Sunny Island offers the following functions for off-grid systems via two multifunction relays (see the Sunny Island inverter
installation manual):
Battery current sensor Shunt for measuring the battery current
A battery current sensor is required in off-grid systems with DC loads or with charge
controllers from third-party suppliers (see Section 2.1 "Intended Use", page 7).
Function Description
Controlling generators A multifunction relay activates if a generator request is received from the
Sunny Island inverter's generator management. With the multifunction relay, you can
control generators with electrical remote-start function or connect a signal generator
for generators with no autostart function.
Control of load-shedding
contactors
A multifunction relay is activated depending on the state of charge of the battery.
Depending on the configuration, you can install a one-stage load shedding with one
multifunction relay or a two-stage load shedding with two multifunction relays. You
can also adjust the limiting values for the state of charge of the battery depending
on the time of day.
Time control for external
processes
External processes can be time-controlled with a multifunction relay.
Display of operating states and
warning messages
You can connect message devices to the multifunction relays to allow operating
states and warning messages from the Sunny Island inverter to be output. One of the
following operating states and warning messages can be displayed for each
multifunction relay:
• The generator is running and is connected.
• A Sunny Island displays an error message of level 2 or higher. Only the error
messages within a cluster are evaluated here.
• A Sunny Island displays a warning. Only the warnings within a cluster are
evaluated here.
• The Sunny Island is in operation in a single system.
• The respective cluster is in operation in a cluster system.
• The Sunny Island is in derating in a single system.
• The respective cluster is in derating in a cluster system.
Control of a battery-room fan The multifunction relay is activated when the charging current leads to the battery
emitting gases. A connected battery room fan is switched on for at least one hour.
Control of an electrolyte pump Depending on the nominal energy throughput, the multifunction relay is activated at
least once a day.
Use of excess energy During the constant voltage phase, a multifunction relay is activated and thus
controls additional loads that can put any excess energy of AC sources in the
stand-alone grid (e.g., of a PV system) to good use.
Device Description