SUNNY ISLAND 5048 - Technical Description - Wind & Sun Ltd.

Additional Functions SMA Solar Technology AG
12 Additional Functions
12.1 Load Shedding
If, over an extended period, the loads connected to the Sunny Island use more energy than that which
the generators connected produce, the battery can deeply discharge. The Sunny Island shuts down
automatically if the state of charge of the battery is too low. This way, the Sunny Island avoids a deep
discharge of the battery. Due to the Sunny Island automatic shutdown, the loads are not supplied with
current and the generators connected to the Sunny Island cannot charge the battery.
In stand-alone grid systems in which generators are connected directly via DC/DC converters, these
generators charge the battery, even if the Sunny Island automatically shuts down. When the battery
reaches a particular state of charge, the Sunny Island can carry out an automatic restart after the
automatic shutdown. After the automatic restart, the generators connected to the Sunny Island can
also charge the battery.
You can prevent the Sunny Island from automatically shutting down by installing a power contactor
for load shedding. The power contactor automatically switches off the loads in the stand-alone system
when the battery charge level is low. The Sunny Island continues operating and can charge the
battery.
Install an external (AC or DC) power contactor between the Sunny Island and the loads (see also
section 21 ”Accessories” (page 216)).
NOTICE!
Faulty system operation due to lack of load shedding.
• Install an external load shedding contactor in case the stand-alone system on the AC
generating side is coupled to PV generators or wind generators.
• If there is overloading due to low energy production or very high energy
consumption, you must be able to switch off consumers.
• Always switch off the consumers, never the energy generators (e.g., Sunny Boy)!
92 SI5048-TB-TEN110340 Technical Description