SMA S Technical Description page 175

SMA Solar Technology AG Glossary
MPP Tracker
Regulation of the power drawn so that a PV generator is operated for as long as possible at the MPP.
This operating point varies with the solar irradiation and temperature conditions of the modules. MPP
tracking optimizes the extraction of electrical power and is a feature of inverters and charge
controllers.
MSD
See Automatic Disconnection Device
Multicluster System
Parallel connection of several clusters on the AC output side in a stand-alone grid or backup system.
The master devices of the individual clusters must be connected by communication cables, and
configured in such a manner that one cluster leads the entire system (see main cluster) and the master
devices of all other clusters (see sub-cluster) communicate with the master of the main cluster.
Multi-String Inverter
An inverter which to a great extent combines the advantages of several string inverters (separate MPP
tracking of individual strings) and a central inverter (low performance-specific costs).
NiCd
Nickel/cadmium battery, contains nickel, cadmium, and potassium hydroxide as the electrolyte.
These require a significantly higher charging voltage, have a lower level of efficiency and are
significantly more expensive than lead acid batteries. However, their robustness, cycle resistance and
low-temperature capabilities mean that they are used in certain special applications.
NLM
Abbreviation for Powerline modem: communication between SMA inverters and the monitoring
devices can be made with a cable, a radio link, or a Powerline modem. Powerline modems use a
carrier frequency of approx. 132 kHz modulated onto the AC cables, and data is transferred using
FSK (Frequency Shift Keying) of this carrier signal. Details on the Powerline modem can be found
(e.g.) in the technical description of the SMA-NLM.
Nominal Charging Throughput
The charging throughput is the cumulative total discharge current over time, measured in ampere
hours (Ah). These meters are not automatically reset after charging. The nominal charging throughput
is the charging throughput with regard to the nominal capacity of the batteries.
Overload Capability
The overload capability of an inverter describes its ability to supply short-term (seconds or minutes)
excessive loads that can be significantly higher than the nominal capacity of battery inverters. The
overload capability is important to allow startup of electrical machines which have a nominal power
output close to the nominal power output of the stand-alone grid inverter, since these machines
typically require six times the nominal current when starting.
Technical Description SBU2200-TEN083320 175