Appendix - Theoretical Outline; Testing Photovoltaic Systems - HT Italia MPP300 Manual De Usuario

9. APPENDIX – THEORETICAL OUTLINE
9.1.

TESTING PHOTOVOLTAIC SYSTEMS

According to the requirements of the laws in force, the result of the test depends on
settings about Temperature effects compensation and PRp calculations (see MASTER
instrument settings):
Corr.Typ
e
Tmod Tcel = PV Module Temp. measured
Tcel = PV module Temp. calculated
Tamb
or

Tcel Tamb
Tenv
nDC
Tcel = PV Module Temp. measured
where:
Symbol
G
p
G
STC
P
n
P
ca

1



Rfv 2

- 1 (Tcel - 40)


100

NOCT
 Previous relationship are valid if Irradiance > Min Irraddiance value (see user manual
of the MASTER instrument) and the Irradiance values are "steady": if IP  1min (Irr
max – Irr min) < 20W/m
The final OUTCOME can be:
 Non-displayable: if the obtained values are inconsistent (e.g. PRp >1.15) or if
irradiation has never reached a steady value > minimum threshold set (see user's
manual of MASTER instrument).
 The maximum performance point (PRp) of the system
The highest performance (maximum value of PRp) is detected according with previous
relationships.
Tcel value
G
 
  
p
NOCT 20
800
 
(if Tcel 40 C)

 
(if Tcel 40 C)
2
PRp calculation

PRp


Rfv 2




G
   
STC
PRp 1

G 100

p
Description
Irradiance on PV module surface
Standard Irradiance = 1000
Nominal Power = sum of all power module (Pmax )
included in the part of PV plant under test
AC Active Power measured
Thermal Corrective factor
Absolute value of Pmax thermal coefficient
Normal Operating Cell Temperature (@ 800W/m
AM=1.5, vel. Aria =1m/s).
EN - 24
P
ca

G
 
p

P
n

G 
STC

 
P
   
ca
T 25
cel

P

n
, 20°C,
2
MPP300
Guidelin
e
CEI
82-25
(Italian
Guideline)
- - -
Meas. unit
 
2
W/m
 
2
W/m
 
kW
 
kW
 
%/ 
C
 
%/ 
C