SMA Multicluster-Box

The SMA Multicluster-Box is an AC distribution box that combines several Sunny Island battery inverter clusters into a single multicluster system. The family includes the Multicluster-Box 6 (6.3-11), the Multicluster-Box 12 (MC-BOX-12.3-20) and the Multicluster-Box 36, and each has its own connection and circuit diagrams. The Sunny Island US manual says SMA multicluster technology supports up to twelve Sunny Island inverters and up to 100 kW. US units need the Multicluster Piggy-Back interface to talk to the box. With the MC-BOX-12.3-20, some multifunction relays in the main cluster master and slave 1 are fixed and cannot be reassigned. The two Sunny Island manuals disagree on whether slave 1 uses relay 1 or relay 2, so check the box documentation. Sunny Island firmware 3.5 works in multicluster systems only with the MC-BOX-12.3-20. A newer Sunny Island firmware table allows only version 1.04.00.R for multicluster systems with the MC-Box-12.3-20, with or without a Grid Connect Box. In stand-alone grid systems, the Multicluster-Box sets the maximum PV inverter output that can be connected. Sunny Island event F 801 means the contactor plausibility check in the Multicluster-Box failed, and the fix is to contact SMA Service.

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• sentence 1: support check: partial - The passages say the box links clusters and is an AC subdistribution, but do not explicitly say it combines clusters as an AC distribution box.
• sentence 3: support check: partial - Up to twelve inverters and 100 kW is stated, and the Piggy-Back is an interface between Sunny Island and the box, but the passages don't say US units need it.
• sentence 6: support check: partial - The passage says the Multicluster-Box specifies the maximum connectable PV inverter output in multicluster systems, in a stand-alone grid section, which is close but not explicitly limited to stand-alone grid.
• sentence 1: review: partial - The passages call the Multicluster-Box an AC subdistribution and describe cluster masters talking to each other in a multicluster system, but they never say outright that it combines several clusters into one system.
• sentence 4: review: partial - The fixed relays and the relay 1 vs relay 2 conflict for slave 1 are supported, but both passages come from sections of the same manual (sma-doc-259761), not two different Sunny Island manuals. -->