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The characterisation of photovoltaic modules is crucial for the assurance of their durability, and thus for the adoption of solar energy as an economically viable and reliable source of electricity. In this thesis the use of line scan photoluminescence and electroluminescence imaging is demonstrated for this purpose. A novel laboratory line scan luminescence imaging tool was designed and built to enable the acquisition of line scan photoluminescence and electroluminescence images on industrial modules. Custom software was developed to facilitate the simulation of line scan luminescence images, based on output from the solar cell modelling program Griddler 2.5 Pro. Experimental and simulated data was used to demonstrate that series resistance faults appear with an inverted contrast in line scan photoluminescence images, enabling the unambiguous differentiation of these faults from other fault types. The detection and classification of multiple different fault types is demonstrated using experimental data obtained on over 50 different module samples, with a combination of line scan photoluminescence and electroluminescence imaging data providing the most effective method of fault identification. It is shown from simulations that the luminescence intensity contrast observed around a series resistance fault is correlated with the power output during nominal operation. Using a fundamental theoretical analysis and experimental results on different silicon solar cell types, it is shown that implied voltages determined from luminescence are significantly less sensitive to variations in sample temperature than terminal voltage measurements. This low temperature sensitivity is highly beneficial for the quantitative monitoring of module degradation, which is demonstrated in a specific case study on light and elevated temperature induced degradation on multicrystalline silicon modules.

In the recent years, photoluminescence based characterisation techniques have been widely adopted in photovoltaics as a common tool due to its contactless nature, fast acquisition time and relatively low cost. This has led to further research into the various aspects of photoluminescence characterisation and so now a lot of solar cell and base material properties can be determined with photoluminescence measurements. One aspect of such photoluminescence-based characterisation that has gotten little attention is the illumination wavelength dependence of the photoluminescence emission from a sample. This is the main focus of this thesis. The illumination wavelength dependence of a solar cell is important as it is designed to operate under a broad spectrum of the sun. The standard metric used to quantify the performance of a device as a function of illumination wavelength is the external quantum efficiency, which requires contact to be made to the sample. It has been previously shown that this metric can be determined from measurement of the spectral response of photoluminescence. The aim of this dissertation project was to investigate the application of photoluminescence techniques to characterise the spectral response of a solar cell in a contactless way. The thesis examines the potential pitfalls that must be avoided while performing a spectral response of photoluminescence measurement such as: using non-monochromatic light sources, spurious luminescence from other layers and angle of incidence of illumination. To highlight the strength of this measurement, an application specific to heterojunction solar cells was developed. Spectral response of photoluminescence was shown to be useful in quantifying the carrier movement between different silicon layers in the front side of a heterojunction solar cell.

Silicon is the most studied semiconductor, having almost every aspect of it being investigated. All this information is spread over a large set of publications, review articles and textbooks and cannot be found in a single location. Furthermore, the available data is not always consistent and depends on the techniques and samples used. This problem even exists for more specialised areas such as the study of defects in silicon photovoltaics, which is the focus of this paper. Currently, if a signature of a defect is experimentally determined a literature search must then be performed through texts going back decades in the hope to find a defect with similar properties. This paper addresses this time consuming activity by introducing an open source text based repository, which anyone can access or contribute to, and that provides clearly arranged information about defects in silicon.