Cluster
A cluster is made up of three Sunny Island inverters and one battery. One Sunny Island inverter per line conductor, i.e., three Sunny Island inverters in total, are connected to form a three-phase stand-alone grid. Within the cluster, one Sunny Island is the master, while the other two are slaves.
Extension cluster
An extension cluster is a cluster within the multicluster system which is subordinated to the main cluster.
The master of the extension cluster follows the instructions issued by the master of the main cluster. The master of the extension cluster sends the operating data of its cluster to the master of the main cluster. If the master of an extension cluster stops operation, then only this cluster shuts down. The multicluster system continues to operate with reduced power.
Main cluster
The main cluster is the leading cluster within a Multicluster system. The master of the main cluster is the central user interface for the main cluster and all extension clusters of a stand-alone grid. The master of the main cluster is superior to the masters of the extension clusters. The tasks performed by the master of the main cluster include the following:
- Starting and stopping the multicluster system
- Controlling and monitoring the masters of the extension cluster
- Communicating with the Multicluster-Box
If the master of the main cluster stops operation, the entire multicluster system shuts down. If a diesel generator is integrated in the stand-alone grid, it will take over the power supply to the loads in this case.
Master
The master is the control and communication center in a cluster. It carries out the following tasks:
- Switching slaves on and off
- Controlling and monitoring the slaves, e.g., regulating frequency and voltage
- Controlling battery charge and discharge
- Monitoring battery capacity and state of charge
- Storing cluster and battery data on SD memory card
- Requesting diesel generator
- Exchanging data with the masters of other clusters
- Updating both slaves after firmware updates
- Displaying system values and system states
- Central capture of user entries
Multicluster-Box
The Multicluster-Box is the main AC distribution board in the multicluster system and a component of the SMA multicluster technology. The Multicluster-Box connects the Sunny Island clusters with the loads and the power generators within a stand-alone grid.
Multicluster system
A multicluster system is made up of several clusters connected in parallel. The power of the multicluster system increases with the number of clusters. The clusters are connected in parallel via a Multicluster-Box. The size of the Multicluster-Box is determined when the system is designed depending on the power requirement.
Slave
A slave is a functional unit subordinated to the master. A slave receives its configuration settings, current firmware updates, and start/stop commands from the master. It transmits its operating data to the master and executes commands issued by the master.
Stand-alone grid
A stand-alone grid is a utility grid which is independent of the public energy supply. A stand-alone grid with Sunny Island is designed as a single-phase or three-phase AC grid which integrates various kinds of power generators (e.g., PV systems, small wind turbine systems and diesel generators).
Batteries for energy storage are also an integral part of stand-alone grids. The Sunny Island battery inverter forms a stand-alone grid and maintains a stable energy supply by regulating all processes.