9 Glossary SMA Solar Technology AG
84 SDesign-BA-BEN120432 User Manual
9Glossary
AC
Abbreviation for "Alternating Current".
Annual energy yield
The annual energy yield is the electrical energy which the PV plant can typically feed into the power
distribution grid over a year.
Central inverter
Inverter concept in which all PV modules are connected to each other (in series or parallel) and a
single inverter is used for feeding power into the power distribution grid.
DC
Abbreviation for "Direct Current".
Displacement power factor cos φ
The DC current of a reactive power inverter is out of phase with the line voltage. The larger this phase
or displacement angle between power and voltage is, the more reactive power is fed into the power
distribution grid. By multiplying the cosine function of the phase or displacement angle with the
apparent power (= voltage x current), you can easily calculate the remaining active power. This is
why the value of cos φ is also called displacement power factor.
Energy usability factor
The energy usability factor indicates which proportion of the electrical energy supplied by the
PV array can be used by the inverter and converted to alternating current. The energy usability factor
is not 100% if the inverter cannot process the entire PV array current in every operating situation due
to current, voltage or output limits.
Independent inputs
Each independent input of an inverter has its own MPP tracker. The operating point of the connected
PV array can therefore be set independently of the operating points of PV arrays connected to other
independent inputs. Multi-string inverters have at least two independent inputs.
Inverter
A device for converting the direct current (DC) from the PV array into alternating current (AC), which
is necessary for connection of most devices and especially for feeding solar energy into an existing
supply grid. Inverters for PV plants usually include at least one MPP tracker, store operating data, and
monitor the power supply line of the PV plant.
