SMA Sunny Island 5048 - Operation Together with PV Inverters

SMA Solar Technology AG Connecting External Sources
Technical Description SI5048-TB-TEN110340 127
14.2.9 Operation Together with PV Inverters
Since electricity is fed into the grid through the relay of the Sunny Island, it must be prevented from
overloading. For this reason, reverse power monitoring is used that, if required, disconnects the
connection to the power distribution grid if the reverse power limit is exceeded.
If the battery is fully charged, the frequency limits the power output of the AC feeding-in generators
(PV inverter) in the stand-alone grid. If the grid is now reconnected, the frequency would be lowered,
if required, as the Sunny Island is synchronized with the grid. The AC feed-in generators would then
feed additional energy into the system and possibly overload the batteries. In order to prevent this, in
this case the stand-alone grid frequency is temporarily increased, in line with the synchronization, until
the AC feed-in generators are disconnected from the stand-alone grid system as a result of the grid
limits being exceeded.
NOTICE!
Damage to the Sunny Island due to high currents.
If the current via the relay exceeds the maximum permissible current, the Sunny Island
disconnects from the grid (relay protection).
• The quantity of PV output installed in the stand-alone grid must never exceed the
maximum quantity allowed by the AC input (see section 22”Technical Data”
(page217)).