Reference : Angle and Spectral Dependence of the Internal and External Quantum Efficiency of Sola...
Dissertations and theses : Doctoral thesis
Physical, chemical, mathematical & earth Sciences : Physics
Physics and Materials Science; Sustainable Development
Angle and Spectral Dependence of the Internal and External Quantum Efficiency of Solar Modules
Reiners, Nils mailto [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit >]
University of Luxembourg, ​Luxembourg, ​​Luxembourg
Docteur en Physique
Siebentritt, Susanne
Blieske, Ulf
Wirtz, Ludger
Borchert, Dietmar
Redinger, Alex
[en] EQE ; IQE ; angle of incidence ; reflection ; photovoltaic ; PV ; solar
[en] Reviewing scientific publications in the field of photovoltaic research, it becomes apparent that most of the investigations are carried out under perpendicular light incidence even though many of the relevant processes in a solar cell or module may strongly depend on the angle of incidence. The reasons for this are most likely due to three facts. Firstly, the equipment that is available for measurements and characterization in research laboratories is mainly constructed for perpendicular incidence. Secondly, the complexity of the analysis strongly increases when the angle of incidence is considered and thirdly, there is still a lack of standardization, which makes it difficult to compare the performance of solar modules at oblique incidence.
Regarding the maximization of the annual energy yield of a solar module it is crucial to be aware of operating conditions in the field. It is obvious that most of the time, light is incident on the module’s surface with an oblique angle. However, it is not sufficient to investigate the short circuit current density effects due to the variation of the angle of incidence as it is often done. The reflection and absorption properties of the materials in a solar module generally vary with the wavelength of the incident light. This is the reason why it is convenient to take the angular and the spectral performance of solar modules into account simultaneously.
In this thesis a synopsis of all the relevant angle and spectral dependent effects is presented for silicon solar cells and modules. It is shown that not only optical effects are occurring, but that the internal quantum efficiency (IQE) also varies with the angle of incidence. It is also shown to which extent the implementation of textured surfaces influences the angle dependence of the external quantum efficiency (EQE) and the IQE. The analysis is performed using a newly developed analytical solar cell model that takes into account all relevant parasitic absorption processes in an untextured solar cell. Using an effective angle approach, the analysis can be extended to a textured solar cell. For more complex structures, a ray tracing tool was developed that is capable of simulating several textured layers and subsequently, of determining the corresponding EQE and IQE at all desired angles of incidence.
The angle and spectral dependence of the cells and modules under investigation were determined using measurement equipment that was particularly constructed for this purpose. The angle dependence of the EQE of the samples was determined with two different systems: A filter monochromator to determine the spectral response and by transforming the electroluminescence spectrum of the samples to the EQE using the opto-electronic reciprocity relation of solar cells. To determine the angle dependence of the IQE, a measurement setup was constructed for the determination of the angular reflection spectra.
Finally, the different angle and spectral dependent effects that were identified were analyzed with respect to their influence on the energy yield estimation of standard solar modules under outdoor conditions.

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