282
M. Pravettoni
response depends on temperature and either active cooling or temperature corrections are required when the temperature variation ranges are above 10 °C (which is
always the case in real installations), in order to limit the measurement uncertainty.
A pyrheliometer (Fig. 10.18b) typically consists of a collimating tube that is
responsible for filtering out the diffuse irradiance and of a thermopile to record the
direct component B(t). Since the collimating tube needs to be pointed precisely
towards the Sun, pyrheliometers need to be installed on 2-axis trackers.
For bifacial modules, the pyranometer is replaced by an albedometer (Fig. 10.18c)
to measure both the global in-plane irradiance and the albedo R(t): it typically
consists of two pyranometers with opposite orientations, one oriented as the front
side of the bifacial modules and one oriented as the rear side.
The global in-plane spectral irradiance G(λ, t) can be measured by an optical
spectrometer (Fig. 10.18d). There are a variety of spectrometers on the market for
outdoor applications, depending on whether they are fast or slow-response and on
the detector (CMOS, CCD or arrays of photodiodes; c-Si or InGaAs). The cheapest
solution is typically a c-Si monochromator spectrometer, able to measure spectral
irradiance from 350 to 1100 nm. Extensions to below 350 nm and above 1100 nm
are possible, but typically more expensive.
We have already observed that the temperature of the modules can be calculated
from the ambient temperature and wind speed via the Faiman equation. Ambient
temperature can be easily measured with high accuracy with thermometers and wind
speed with an anemometer. Alternatively, thermocouples or resistance temperature
detectors (RTDs) could be used to measure the temperature directly at the surface of
the module, without the need of using the Faiman equation and ambient parameters.
Finally, while the geometry of installation and size of the modules are straightforward, both the spectral responsivity and the angular transmittance of the PV modules can only be measured by specialized testing laboratories. In most cases, this
information can be provided directly by the module manufacturers.
References
1. D. Faiman, Prog. Photovolt: Res. Appl. 16, 307–315 (2008)
2. M. Bliss, T.R. Betts, R. Gottschalg, Meas. Sci. Technol. 21, 115701 (11 pp) (2010)
3. N. Martin, J.M. Ruiz, Sol. Energy Mater. Sol. Cells 70, 25–38 (2001)
4. N. Martin, J.M. Ruiz, Sol. Energy Mater. Sol. Cells 110, 154 (2013)
5. T.S. Liang, M. Pravettoni, C. Deline, J.S. Stein, R. Kopecek, J. Prakash Singh, W. Luo, Y.
Wang, A.G. Aberle, Y.S. Khoo, Energy Environ. Sci. 12, 116–148 (2019)
6. M. Köntges et al., in IEA PVPS, Report IEA-PVPS “Review of Failures of Photovoltaic
Modules” T13-01 (2014)
7. W. Luo, Y.S. Khoo, P. Hacke, V. Naumann, D. Lausch, S.P. Harvey, J. Prakash Singh, J. Chai,
Y. Wang, A. G. Aberle, S. Ramakrishnaab, Energy Environ. Sci. 10, 43–68 (2017)
8. K.G. Bedrich, W. Luo, M. Pravettoni, D. Chen, Y. Chen, Z. Wang, P.J. Verlinden, P. Hacke, Z.
Feng, J. Chai, Y. Wang, A.G. Aberle, Y.S. Khoo, IEEE J. Photovolt. 8(5), 1281–1288 (2018)
9. A. Virtuani, M. Caccivio, E. Annigoni, G. Friesen, D. Chianese, C. Ballif, T. Sample, Prog.
Photovolt: Res. Appl. 27(4), 328–339 (2019)
M. Pravettoni
response depends on temperature and either active cooling or temperature corrections are required when the temperature variation ranges are above 10 °C (which is
always the case in real installations), in order to limit the measurement uncertainty.
A pyrheliometer (Fig. 10.18b) typically consists of a collimating tube that is
responsible for filtering out the diffuse irradiance and of a thermopile to record the
direct component B(t). Since the collimating tube needs to be pointed precisely
towards the Sun, pyrheliometers need to be installed on 2-axis trackers.
For bifacial modules, the pyranometer is replaced by an albedometer (Fig. 10.18c)
to measure both the global in-plane irradiance and the albedo R(t): it typically
consists of two pyranometers with opposite orientations, one oriented as the front
side of the bifacial modules and one oriented as the rear side.
The global in-plane spectral irradiance G(λ, t) can be measured by an optical
spectrometer (Fig. 10.18d). There are a variety of spectrometers on the market for
outdoor applications, depending on whether they are fast or slow-response and on
the detector (CMOS, CCD or arrays of photodiodes; c-Si or InGaAs). The cheapest
solution is typically a c-Si monochromator spectrometer, able to measure spectral
irradiance from 350 to 1100 nm. Extensions to below 350 nm and above 1100 nm
are possible, but typically more expensive.
We have already observed that the temperature of the modules can be calculated
from the ambient temperature and wind speed via the Faiman equation. Ambient
temperature can be easily measured with high accuracy with thermometers and wind
speed with an anemometer. Alternatively, thermocouples or resistance temperature
detectors (RTDs) could be used to measure the temperature directly at the surface of
the module, without the need of using the Faiman equation and ambient parameters.
Finally, while the geometry of installation and size of the modules are straightforward, both the spectral responsivity and the angular transmittance of the PV modules can only be measured by specialized testing laboratories. In most cases, this
information can be provided directly by the module manufacturers.
References
1. D. Faiman, Prog. Photovolt: Res. Appl. 16, 307–315 (2008)
2. M. Bliss, T.R. Betts, R. Gottschalg, Meas. Sci. Technol. 21, 115701 (11 pp) (2010)
3. N. Martin, J.M. Ruiz, Sol. Energy Mater. Sol. Cells 70, 25–38 (2001)
4. N. Martin, J.M. Ruiz, Sol. Energy Mater. Sol. Cells 110, 154 (2013)
5. T.S. Liang, M. Pravettoni, C. Deline, J.S. Stein, R. Kopecek, J. Prakash Singh, W. Luo, Y.
Wang, A.G. Aberle, Y.S. Khoo, Energy Environ. Sci. 12, 116–148 (2019)
6. M. Köntges et al., in IEA PVPS, Report IEA-PVPS “Review of Failures of Photovoltaic
Modules” T13-01 (2014)
7. W. Luo, Y.S. Khoo, P. Hacke, V. Naumann, D. Lausch, S.P. Harvey, J. Prakash Singh, J. Chai,
Y. Wang, A. G. Aberle, S. Ramakrishnaab, Energy Environ. Sci. 10, 43–68 (2017)
8. K.G. Bedrich, W. Luo, M. Pravettoni, D. Chen, Y. Chen, Z. Wang, P.J. Verlinden, P. Hacke, Z.
Feng, J. Chai, Y. Wang, A.G. Aberle, Y.S. Khoo, IEEE J. Photovolt. 8(5), 1281–1288 (2018)
9. A. Virtuani, M. Caccivio, E. Annigoni, G. Friesen, D. Chianese, C. Ballif, T. Sample, Prog.
Photovolt: Res. Appl. 27(4), 328–339 (2019)