MI 3109 EurotestPV Lite
Appendix E
– PV measurements – calculated values
74
Panel:
Measured U and I are corrected to STC conditions:
)
(
))
(
1
(
meas
STC
meas
STC
rel
meas
STC
Irr
Irr
T
T
I
I
)
(
))
ln(
)
(
(
_
meas
STC
meas
STC
meas
STC
rel
meas
OC
meas
STC
I
I
Rs
Irr
Irr
T
T
U
U
U
nom
Rs
N
M
Rs
where I
meas
and U
meas
are measured direct current and voltage at panel,
Irr
STC
is
irradiance at STC, Irr is measured irradiance,
α is irradiance correction factor, α
rel
and
β
rel
are the current and voltage temperature coeff. off panel,
T
STC
is temperature at STC,
T
meas
is measured temperature,
Rs
is serial resistance of panel / string,
M
is number of
modules in serial and
N
is number of modules in parallel.
I
stc
, U
stc
Calculated values of current and voltage at standard test condition
I
meas
, U
meas
measured direct current and voltage at panel
Irr
stc
irradiance at STC
Irr
measured irradiance
α
irradiance correction factor (typical 0,06)
α
rel
, β
rel
current and voltage temperature coeff. of panel
Tstc
temperature at STC
T
meas
measured temperature
Rs
nom
serial resistance of module
Rs
serial resistance of string
M
number of modules in serial
N
number of modules in parallel
STC
STC
STC
P
I
U
Conversion efficiency:
1. inverter:
AC
DC
P
P
