Title: Integral methods of measurement for photovoltaics
Authors: Plag, Fabian, Physikalisch-Technische Bundesanstalt (PTB), Fachlabor 4.5, Angewandte Radiometrie
Contributors: HostingInstitution: Physikalisch-Technische Bundesanstalt (PTB), ISNI: 0000 0001 2186 1887
Resource Type: Text / Dissertation
Publisher: Physikalisch-Technische Bundesanstalt (PTB)
Rights: Download for personal/private use only, if your national copyright law allows this kind of use.
Relationships: IsPartOf: ISSN 0341-6712
IsIdenticalTo: ISBN 978-3-95606-497-5
References: DOI 10.7795/720.20180517
Dates: Available: 2020-06-15
Created: 2019-12
File: Download File (application/pdf) 6.85 MB (7182882 Bytes)
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SHA256 Checksum: 8a93a2f7cd888e1b5b1d54d6070891f5ab0e9a23d32c3324a268fc3c14d8b73a
Keywords: photovoltaic metrology ; calibration ; angle of incidence ; spectral responsivity ; diffuse irradiance ; optical losses ; energy rating ; EMPIR ENG02 PV-Enerate
Abstract: In the domain of solar irradiance measurements, a wide range of irradiation conditions exist. While the primary calibration of reference solar irradiance detectors is usually performed using only direct irradiance, secondary calibrations are conducted with a diffuse incident irradiance component. If the optical properties vary between the reference and the device under test, spectral and angular dependencies of the incident irradiance and the detectors’ responsivities may result in a mismatch when referring to defined reference conditions. In this thesis a new multidimensional model is presented. It introduces spectral-angular effects to the field of photovoltaic metrology, with a focus on quantifying their impact on high-accuracy device calibrations. A novel measurement technique has been developed in this thesis. It allows the characterization of the angle of incidence and polarization dependence of the spectral responsivity of solar cells. The enhanced modeling approach considers the anisotropic spectral radiance for arbitrary device orientation and spectrally resolved ground reflections. To account for these effects, both the spectral radiance of the source and the angular-dependent spectral responsivities of the detectors are considered. Angular mismatches of more than 1 % are identified for the investigated examples. The proposed model allows the spectral and angular effects to be determined and corrected. The knowledge of this correction factors allows their consideration for establishing measurement uncertainty budgets of high-accuracy outdoor measurements. In addition to global natural sunlight measurements, the approach can be also utilized for the evaluation of indoor laboratory measurements with solar simulators containing diffuse light. Additionally, a study on the impact of simplifications in the model is shown. A separate section treats the determination of AOI dependent optical losses with regard to PV module energy rating procedures. This study on angular losses includes a discussion on the procedure’s uncertainties. The impact of the mathematical model proposed in the international standard IEC 61853-3 is identified to be the most crucial contribution to the uncertainty of the angular loss. This thesis includes an exemplary energy rating scenario that focusses on the determination of the generated electricity of PV devices under reference climate profiles. This comparison considers three different models. The energy loss differences at one exemplary clear sky day are ranging from 0.3 % to 2.7 %, solely for spectral and angular effects. Finally, the results are discussed and an outlook for subjects of future research is presented. Meanwhile, the findings of this work are discussed in a standardization committee and an interlaboratory comparison on AOI dependent measurements has been completed.
Citation: Plag, Fabian. Integral methods of measurement for photovoltaics, 2019. Physikalisch-Technische Bundesanstalt (PTB). DOI: https://doi.org/10.7795/110.20200615