Synchronisation Of The Stand-Alone Grid To The External Energy Source; Interactions Between External Energy Sources And The Stand-Alone Grid; Parameters For The Generator And Electricity Grid - SMA SUNNY ISLAND 8.0H Installation Manual

10 External Energy Sources in the Off-Grid System
The generator and electricity grid cannot feed electricity into the off-grid system at the same time.
An external automatic transfer switch is required to use a generator and the electricity grid.
The off-grid inverter does not have an integrated automatic transfer switch.
10.4 Synchronisation of the Stand-Alone Grid to the External
Energy Source
Synchronisation allows the off-grid inverter to switch the stand-alone grid to the external energy
source.
If an external AC voltage is present at the off-grid inverter, the off-grid inverter synchronises the stand-
alone grid to the external AC voltage. When the stand-alone grid is synchronised to the external
energy source, the off-grid inverter closes its internal transfer relay. When the internal transfer relay is
closed, the external energy source determines the voltage and frequency in the stand-alone grid.
10.5 Interactions between External Energy Sources and the
Stand-Alone Grid
External energy sources influence the power control of the AC sources in the stand-alone grid
(e.g. PV inverters). The off-grid inverter regulates the power output of the connected AC sources by
means of the stand-alone grid frequency. The higher the stand-alone grid frequency, the lower the
power that is fed into the stand-alone grid from the PV inverters and wind power inverters.
If you start a generator manually, the off-grid inverter synchronises the frequency of the stand-alone
grid to the frequency of the generator voltage and connects the stand-alone grid to the generator
voltage. Power control of the AC sources in the stand-alone grid is therefore not possible during
synchronisation.
The off-grid inverter briefly raises the stand-alone grid frequency to the shutdown limit value of the AC
sources if all of the following items apply:
• The target value of the cell voltage of the battery has been reached.
• The AC sources in the stand-alone grid are limited in their power output by the off-grid inverter.
• The external energy source meets the conditions for the synchronisation of the stand-alone grid
to the voltage of the external energy source.
The AC sources switch off due to the significant increase in frequency. In this way, the off-grid inverter
protects the batteries against overcharge.
10.6 Parameters for the Generator and Electricity Grid
There is only one terminal for external energy sources. To distinguish between the generator and
electricity grid, the off-grid inverter has different parameters for the connection of external energy
sources: grid parameters and generator parameters.
For operation on the electricity grid, there are generally strict limiting values for voltage and
frequency. These strict limiting values are not suitable for generator mode. Distinguishing between grid
parameters and generator parameters means that you can generally alternate between the use of a
generator and the electricity grid with no further adjustments.
There are specific parameters for grid management and generator management and there are shared
parameters and display values.
130 SI80H-60H-OffGrid-IA-en-11
SMA Solar Technology AG
Installation Manual