SMA America, LLC
Connecting External Sources
Technical Description
SI5048U-TUS121440
133
14.2.9 Limits and Power Adjustment
The Sunny Island draws power from the public grid during each phase using the current specified via
the ”232.03 GdCurNom” parameter. The power that is not directly used by the loads flows into the
battery for charging. At the same time, the limits for the AC charging current (”210.02
InvChrgCurMax” parameter) on the Sunny Island and the DC charging current (”222.01
BatChrgCurMax” parameter) are active. If the battery voltage reaches the charging voltage nominal
value, it is also reduced (see section 13.4 ”Charge Control” (page 107)).
If the current set using the ”#232.03 GdCurNom” parameter is not sufficient for powering the loads,
the battery provides support.
14.2.10 Operation in Conjunction 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 which, if required, establishes the
connection to the main power grid if the reverse power limit is exceeded, or if an excessive load is
applied to the relay.
If the battery is fully charged, the frequency limits the power output of the AC feed-in generators
(PV inverters) in the off-grid power system. 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 off-grid frequency is temporarily increased, in line with the
synchronization, until the AC feed-in generators are disconnected from the off-grid power system as
a result of the grid limits being exceeded.
Silent Mode Active
When silent mode is activated, the grid cannot be supported!
A short grid outage can occur. This way, the voltage fed to the loads will be interrupted for
a short time.
NOTICE
Overload of the Sunny Island through high currents. Destruction of the Sunny Island.
If the current flowing through the relay exceeds the maximum permissible current, the grid
is disconnected (relay protection).
• Do not install more PV power in the off-grid power system than the maximum quantity
allowed by the AC input (see section 22 ”Technical Data” (page 216)).
