Sunny Island
Installation & Operating Instructions
BWRI33-12:EE
- 119 -
SMA Regelsysteme GmbH
12.3 Overload Behavior
One major feature of an island inverter is the performance in terms of overload.
While the consumers within the island grid will want an uninterrupted and continuous
power supply the plant operators will want a long term reliability and operation of the
inverter and the batteries as well. The manufacturer of the island inverter must take
fundamental aspects in terms of safety into account in order to provide maximum
safety for the personnel and the connected components.
The overload capacity of the Sunny Island depends on such requirements as well:
In a high overload situation (more than double the nominal power) the Sunny Island
trips the internal AC fuse F2 after a few seconds. The battery management prevents
an intensive discharge that could damage the batteries in case the battery charge
level is low.
In an overload situation between 1.3 x and 2 x nominal power the performance
mainly depends on the behavior of the AC fuse. The behavior of the fuse in this load
range mainly depends on the ambient temperature and the tolerances of the manu-
facturer. The thresholds that are mandatory are available in the IEC/EN 60947 ("R").
In an overload Situation between nominal power and 1.3 x nominal power the per-
formance mainly depends on the ventilation and the resulting temperature inside the
enclosure of the Sunny Island. In case the Sunny Island is installed in a room within
the specified ambient temperature an automatic deactivation of the Sunny Island due
to overheating will normally take place after a few hours or even not at all.
Please note that any operation of the Sunny Island beyond the specified
limits in terms of temperature and output power etc. has negative influ-
ence on the lifetime of the Sunny Island.
One reason for the careful observation of the overload performance is the connection
or activation of “problem loads“. These are consumers that extract a very high
amount of power from the grid when they are activated. This power can be very
