SMA SUNNY DESIGN 3 - Manual (Page 32)

7 Glossary SMA Solar Technology AG
32 SD3-SDW-BA-en-20 User Manual
7 Glossary
AC
Abbreviation for "Alternating Current".
Annual Energy Yield
The annual energy yield is the electrical energy that the PV system can typically feed into the utility grid in one 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 external utility grid.
DC
Abbreviation for "Direct Current".
Displacement Power Factor cos φ
The AC current of a reactive-power capable inverter is phase-shifted compared to the grid voltage. The larger this line
conductor angle or phase shift angle between power and voltage is, the more reactive power is fed into the utility grid.
By multiplying the cosine function of the line conductor angle or phase shift 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. For economic reasons,
an energy usability factor of 99.8% is desirable.
Genset
Electric generator with a combustion engine (e.g. diesel, gas or petrol).
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) supplied by the PV array into alternating current (AC), which is necessary
for connection of most devices and especially for feeding solar energy into an existing transmission line. Inverters for
PV systems usually contain one or more MPP trackers, store operating data, and monitor the grid connection of the
PV system.
Inverter Efficiency
The inverter efficiency is the average inverter efficiency during a typical operating year.
The inverter efficiency can be simply put using the following formula:
Formula for calculation of inverter efficiency
Inverter efficiency =
Annual energy yield
Annual utilization of electrical energy of the PV array