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International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
“CHARACTERIZATION OF CONCENTRATED
LIGHT BEAMS WITH APPLICATIONS TO
SOLAR CONCENTRATORS”
Part B:
“Radiometric methods”
Antonio Parretta
ENEA – Bologna
OUTLINE
1.
2.
The Double Cavity Radiometer:
i)
Theory
ii)
Practical realization
iii)
Calibration
iv)
Applications
Introduction to radiometers for solar concentrators with
cylindrical receivers
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
DCR-1 Radiometer
Optical fibre
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
DCR-1 Radiometer
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
DCR-1 Radiometer
Solar Simulator
Gauge head
Diode array
Spectrograph
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
DCR-1 Radiometer
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
DCR-1 Radiometer
Spectrum of light
Control
module
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
DCR-1 Radiometer
Touchscreen of the control module
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
DOUBLE-CAVITY RADIOMETER (DCR)
Calibration
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
DCR Calibration at PASAN Solar Simulator
Console
simulator +
PC
co
bo
la
sl
I/V
cr
lf
T (°C)
dia
sc
I/V
sc
ra
Lamp power
supply
Console
DCR
Radiometer
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
DCR Calibration at PASAN Solar Simulator
Fresnel lens
DCR gauge head
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
DCR Calibration
0,20
0,15
Isc DCR (A)
No baffles
Ins4
Ins3
Ins2
Ins1
0,10
0,05
0,00
0
2
4
6
8
10
12
14
Isc REF (A)
Calibration curves obtained by pulsed measurements of Isc on the DCR
and on the reference SP-HECO252 cell.
Measurements taken at T=25°C. Input window area: Sin= 1.96 cm2.
Reflectance of DCR wall
100
99
98
R (average) =95,44 (%)
Reflectance (%)
97
96
95
94
93
92
Measurements made on two DCR caps
91
90
200
400
600
800
1000
1200
Wavelength (nm)
Reflectance of DCR internal wall as function of wavelength.
Attenuation factor for power measurements
500
Rw92%
Rw94%
Rw96%
Rw98%
P
fA exp
Attenuation factor, fA
P
400
300
Sin = 1.96 cm
Sda = 0.0 cm
2
2
200
100
0
0,00
0,25
0,50
0,75
1,00
2
Insert area, Sc (cm )
Experimental attenuation factor vs. insert area, compared to
the curves of the optical model. Added dark area = 0 cm2.
Attenuation factor for power measurements
500
Sin = 1.96 cm
400
Sda = 1cm
2
2
Attenuation factor, fA
P
Rw92%
Rw94%
Rw96%
Rw98%
P
fA exp
300
200
100
0
0,00
0,25
0,50
0,75
1,00
2
Insert area, Sc (cm )
Experimental attenuation factor vs. insert area, compared to
the curves of the optical model. Added dark area = 1 cm2.
Attenuation factor for flux density measurements
40000
35000
Attenuation factor, fA
G
30000
Sm = 1.21cm
Rw = 98%
2
25000
20000
15000
Sin=0.02cm
2
Sin=0.05cm
2
Sin=0.10cm
2
Sin=0.20cm
2
10000
5000
0
0,00
0,05
0,10
0,15
0,20
2
Insert area, Sco (cm )
Experimental data of attenuation factor vs. insert area, compared to
the curves of the analytical optical model. Added dark area = 1 cm2.
CONCLUSIONS ABOUT DCR
The DCR radiometer is a simple and easy-to-use apparatus.
Main features of DCR:
i)
It measures both the total power of the beam and the flux
density distribution.
ii) It allows the controlled and precise attenuation of the incident
radiation.
iii) It can operate between about 1 sun up to thousands of suns.
iv) The response is quite independent of the incident direction and
divergence of the beam.
v) The measurement is made in a stationary regime.
ACKNOWLEDGEMENTS to M. Pellegrino, G. Flaminio (ENEA-Portici)
for the PASAN calibration measurements.
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
RADIOMETERS FOR SOLAR CONCENTRATORS
WITH CYLINDRICAL RECEIVERS
Introduction
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
Photovoltaic collar (1st version)
Eleven Photodetectors: HECO 252 SunPower cells
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
Photovoltaic collar (2nd version)
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
Photovoltaic collar (2nd version)
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
Photovoltaic collar (2nd version)
Photo taken by a CCD from the bottom of the mirrors
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
Photovoltaic collar (2nd version)
Corresponding photodetectors signals
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
Photovoltaic collar (2nd version)
Photodetectors temperatures
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006
CONCLUSIONS ABOUT PV COLLAR
A static PV collar has been developed
It allows to obtain precise measurements of
concentrated radiation
Temperature of photodetectors is acceptably low
Ways to select the incoming radiation are being studied
A moving version of the PV collar is under project
Optical calibration with PASAN at Portici for absolute
measurements are foreseen
Ist International School on Concentrated Photovoltaics, Ferrara 2-6 September 2006