Sunny Island 4500
Installation & Operating Instructions
BWRI45-13-EE0304
- 145 -
SMA Regelsysteme GmbH
11.1 Photovoltaically powered Island Grid
Fig. 11.1 shows a basic example for an island grid using exclusively solar energy. To
reduce the requirements in terms of battery and PV generator size it is possible to
provide an additional circuitry (see Fig. 12.5) that allows the temporary connection of
an external generator whenever necessary. In an island grid that only consists of
power sources based on renewable energy optimum battery management can only
be guaranteed if it is combined with load management. This is due to the fact that
energy yield may vary strongly depending on the season. The Sunny Island is opti-
mized for the integration of grid-feeding PV inverters, especially Sunny Boys, in an
island grid and allows sophisticated load management. The Sunny Boy inverters and
the Sunny Island communicate via the COM2 interface (RS485). Via this interface the
Sunny Island derates the output power of the Sunny Boys, in case the battery is
about to be overcharged. Even a derating of the power without additional cabling via
the frequency is possible and recommended. (This depends on the Sunny Boys
firmware version)
Disconnection of consumers
In an island grid that does not include a feeder available at any time (combustion ag-
gregate) the consumers connected should be classified in terms of which battery
states have to be reached for the Sunny Island to switch them off or - if required -
switch them on. This allows a careful operation of the battery and a high reliability of
the most important consumers. Any consumers in the island grid whose temporary
switch-off will not have serious consequences (such as air conditioning) should be
used in order to reduce consumption within the island grid in case of a low battery.
The Sunny Island should disconnect these consumers via one of the freely configur-
able relays (K1 to K8) if for example the battery state N3 or N4 is reached. When bat-
tery state L2 is reached all consumers – if possible - should be switched off at the
latest. A model for wiring is shown in Chapter 3.4.10.