PV-Engineering PVPM 2540C - 12 List of Symbols

12List of symbols 33
12 List of symbols
AM Air-Mass, relative way length for the sunlight through the atmosphere of the earth
E Irradiance
E
0
1000 W/m
2
(Irradiance at STC)
E
eff
Irradiation, measured with a crystalline PV cell
FF Fill factor: relationship Isc*Uoc/(Ipmax*Upmax), for crystalline modules about 0.75 = 75%, smaller values can
indicate insufficient power
I Current
I
m
Short form for Ipmax
I
ph
Photo current
I
pmax
Current at Pmax
I
pmax0
Current at Pmax0 (at STC)
I
sc
Short circuit current
I
sc0
Short circuit current (at STC)
MPP Maximum Power Point, other description for P
max
NOCT Nominal Operating Cell Temperature,
cell operating temperature at T
ambN
and E
N
.
P Power
P
max
Recent maximum power of a solar cell
P
pk
Peak Power, maximum power of the solar cell at STC
PV Photovoltaic
R Resistance
R
pv
Photovoltaic resistance (calculation factor only, no real resistor)
R
s
Series internal resistance, apart from resistances in the module e.g. cable/plug resistance, intrinsic resistance of
crystalline modules about 0,5 ohms, of thin film cells 2-3 ohms. In strings R
S
is determined strongly by the
resistances of the cables.
R
p
Parallel internal resistance
STC Standard Test Conditions fE0=1000W/m
2
, AM1.5, T=25°C
T
mod
Current module temperature (at the back side of the module)
U Voltage
U
m
Short form for Upmax
U
oc
Open circuit voltage
U
oc0
Open circuit voltage (at STC)
U
pmax
Maximum power voltage
Operation manual for PVPM devices PV-Engineering GmbH