Connecting External Sources
SMA America, LLC
128
SI5048U-TUS121440
Technical Description
Whenever this information is missing (in case of maintenance or a failure) the Sunny Boy inverters
switch from the ”OffGrid” to the ”grid-tied” setting and take over the Anti-Islanding function. This
ensures that an Anti-Islanding is active at all times according to UL1741 when feeding into the public
grid.
If the Sunny Island continues working it tells the Sunny Boy inverters to switch back to ”OffGrid”
settings and performs the Anti-Islanding again.
This function can be realized with the Sunny Islands in combination with the PV inverters
Sunny Boy 3000‑US/3800-US/4000-US/5000-US/6000-US/7000-US/8000-US.
RS485 Piggy-Backs must be integrated into the Sunny Island as well as in the Sunny Boy inverters. In
addition, a CAT5 cable is needed.
14.2.5 Grid Reconnection
In off-grid operation, the Sunny Island constantly checks whether the grid has been reconnected (see
above). The following conditions have to be fulfilled to guarantee that the Sunny Island synchronizes
with the grid and connects to the grid:
• The frequency of the grid has to be between the values of the ”232.05 GdFrqMin” and
”232.06 GdFrqMax” parameters for the time defined in the ”232.07 GdVldTm” parameter.
• The voltage of the public grid has to be between the values of the ”232.01 GdVtgMin” and
5 V below the ”232.02 GdVtgMax” parameter for the time defined in the ”232.07 GdVldTm”
parameter.
14.2.6 Grid Operation
In grid operation, the off-grid power system and main power grid are connected. The Sunny Island is
connected along with the off-grid power system to the main power grid. In this case, the voltage and
frequency in both grids are identical.
In grid operation, the grid monitoring checks whether the permissible limits for voltage and frequency
(see Grid Reconnection) are maintained or whether the grid fails to assume powering the off-grid
power system. To do this, the main power grid is disconnected (grid backup operation).
The battery is generally charged or its charge is maintained on the grid.
Charge Mode
Charge mode on the grid is indicated by energy flowing to the battery. The battery is charged until
the respective charge process (Boost, Full, Equalize) has been completed and the system changes to
float charge (Float) (see section 13.4 ”Charge Control” (page 107)).
Grid Failures
All grid failures that occur during grid operation affect the off-grid power system.
