11 Glossary SMA Solar Technology AG
68 SI80H-BE-BEN120810 Operating Manual
Cluster
Multiple off-grid inverters which are switched in parallel on the DC side, and which are connected to
a shared battery system. On the AC output side, these inverters can form a single-phase or three-phase
stand-alone grid. The inverters in a cluster must be connected via data cables and configured in such
way that one inverter manages the cluster as a master and all other devices communicate with the
master as slaves.
Constant current phase
Charging phase in which the battery can be charged using the maximum charging current.
Constant V phase
See Constant voltage phase
Constant voltage phase
A charging phase using constant charging voltage to charge the battery. The charging current
constantly decreases in this phase.
C rate
The nominal capacity specification is always provided with the discharge time on which the capacity
is based. The nominal capacity is the product of the constant charging current I
N
and the discharge
time t
N
, which passes between commencement of discharging the fully charged battery and when the
final discharge voltage U
S
is reached. For stationary batteries, the C10 capacity is usually specified.
A battery with a capacity of C10 = 200 Ah can be discharged for 10 hours at a nominal current of
0.1×C10=I
10
=20A.
Derating
A controlled power reduction, usually dependent on component temperatures. Compared with the
practice of completely shutting down the device, the effect on the stand-alone grid is smaller with
derating.
Electrolyte
Allows the conduction of ions within a battery. The electrolyte in lead acid batteries is diluted sulphuric
acid.
Equalise charge
See Equalisation charge
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