SUNNY ISLAND 5048 - Technical Description - Wind & Sun Ltd.

SMA Solar Technology AG Multicluster Operation
16.4 Generator Operation
The main master's generator request comprises its own request (based on SOC, time, etc.) and
possible requests from one or more extension clusters. The generator remains in a requested state as
long as a request is present.
Generator request
The established generator request at the extension clusters is transferred to the main master
via a communication connection.
16.5 Behavior with Different Charge States
In Multicluster systems, each cluster has its own battery bank. To prevent the charge states of the
various battery banks from diverging over time, a function for equalization of the charge states is
integrated into the Sunny Island devices. This distributes the power to all clusters, however, it is not
always distributed identically. Instead, the cluster with the highest state of charge discharges the most
power or charges the battery with the lowest power.
The differences in power depend on the difference in the state of charge and total 1 % of the nominal
power for each 1 % of difference in the state of charge. Thus, when initial charge states differ,
equalization of the charge states over the course of time is ensured. If all batteries in the various
clusters have the same capacity, the charge states should always be within a few percent of each
other. Only if a fault occurs, or upon deliberate deactivation of individual clusters, can a greater
imbalance arise, but even so, such an imbalance should also be equalized after one day at the latest.
Nominal capacity of the battery banks
Ideally, the various battery banks should all have the same nominal capacity.
If the nominal capacity varies by up to 30 %, a similar average state of charge is ensured
via the equalization function. However, the smallest battery is then cycled more intensively.
The rated output power and overload capability are no longer the value of an individual
device multiplied by the number of devices. Instead, it is 10 % – 20 % lower for the cluster
with the smaller battery.
Technical Description SI5048-TB-TEN110340 137