Sunny Island 4500
Installation & Operating Instructions
BWRI45-13-EE0304
- 172 -
SMA Regelsysteme GmbH
11.7 Multiple Sunny Island Systems (w/o Data interchange)
Sunny Islands with firmware 3.00
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, and higher are able to operate in parallel without
any communication. The information about the energy resp. load status is derived
solely from the frequency and the voltage of the AC grid („droop mode“, see Chapter
2.1.3).
This means, as a side effect, that it is not possible to synchronize the island grid to an
external generator/utility in this mode, because any frequency and voltage variation
will inevitably lead to an undesirable misinterpretation by all Sunny Islands. In fact an
integration of an external, grid forming energy source is only possible if it a) can syn-
chronize itself to the grid and b) is capable of adjusting to P vs. f and Q vs. V
characteristics (see Fig. 2.3 and Fig. 2.4).
As PV-inverters of the Sunny Boy family can be prepared for adjusting to the P vs. f
characteristics there is no need for special settings in the Sunny Islands concerning
their power limiting.
In this operating mode each Sunny Island acts independently from other Sunny Is-
lands. Each Sunny Island (resp. each three-phase cluster) has therefore to be con-
nected to its own battery.
There is no limit in the number of Sunny Islands in such systems in principle. How-
ever, without further considerations it should be limited to four Sunny Islands con-
nected in parallel per phase to play it safe.
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estimated completion date: 4Q/04