MI 3109 EurotestPV Lite
Appendix E
– PV measurements – calculated values
72
Appendix E
– PV measurements - calculated
values
Calculation with known U, I (DC, AC), configuration of modules into a string (M -
modules in serial, N - modules in parallel), environment parameters (Irr, T) and
data supplied by the panels manufacturer (U, I (AC, DC), phase, Istc,
α, β, γ,
Pnom, NOCT, Irr, Irr
stc
, Tamb or Tcell)
Panel (DC):
Where
for INVERTER measurements
for PANEL measurements
WP stands for DC Working Point of the inverter
– should be actual MPP of the
connected PV string but not necessary.
Inverter (AC):
3
,
,
1
cos
AC
meas i meas i
i
i
P
U
I
U, I and phase are measured on inverter connectors, i is for multi-phase systems (i = 1
÷ 3).
Conversion efficiency:
1. panel:
Where
measured output power of the panel at STC and
nominal output power of the panel at STC
,
,
where
P
nom
is nominal power of panel at STC,
Irr
STC
is nominal irradiance at STC (
Irr
STC
=
1000 W/m
2
),
Irr
is measured irradiance,
M
is number of modules in serial and
N
is
number of modules in parallel.
η
2
Efficiency of panel (simplified)
