Aspects of characterization methods and product development within applied photovoltaics

Photovoltaic energy has within the last decade transformed itself from being a small niche to be a significant energy source and has during the same time, undergone huge capacity expansions. In the future photovoltaic energy is predicted to be the main driver in the expansion of renewable energy. This development is facilitated by large cost reductions, however to achieve a low price of energy additional measures including low operating costs as well as confidence by the financial stakeholders are required.

The operating costs can be reduced by automatic fault finding methods where the labor effort is greatly reduced, and the confidence from financial stakeholders is increased via accurate performance estimates backed up by lab measurement. In addition, building integrated photovoltaics offers great advantages contributing to the energy transformation in the build environment such as cost efficiency, production at the place of consumption but are also subjected to physical and aesthetical constraints.

Solar powered products that uses a battery and a solar panel can be developed to be aesthetically pleasing, and if right engineered, provide reliable functionality and at the same time provide huge savings on cabling especially in the urban environment. This thesis presents result on work within two methods for automatic fault detection.

Impedance spectroscopy is used to find early traces of degradation and it is shown that impedance spectroscopy can be used to identify micro cracks and potential induced degradation on crystalline PV modules. Methods for acquiring daylight electroluminescent images from a drone are also presented, where it is shown that biasing a string with a waveform a luminescent signal can be achieved by subtracting images without bias from images under bias.

This technique allows, together with the use of optical bandpass filters, to filter the ambient light. Images of sufficient quality can be acquired, and hereby proof of concept for outdoors electroluminescent imaging is presented. Further, this thesis presents results from an optical characterization setup which is developed for characterizing the relative transmission loss as a function of incident angle, and the measurement system is validated via a round robin measurement campaign.

These results can be used to increase confidence to the performance models used as input for the financial calculations. Further work on optimizing appearance for building integrated modules are presented where an inorganic coating is used to blacken the ribbons. The optical measurement setup is expanded to conduct single plane reflection measurements, where the results can be used for color assessment of photovoltaic devices as well as glare assessment.

These measurements are highly relevant in the assessment of BIPV and provides documentation towards aesthetical constraints. The optical work is concluded by demonstrating a reflector system for solar powered sensor masts, where a prototype is modelled, developed and tested. The thesis concludes by presenting the development of a laboratory and products for product integrated photovoltaics focused on lighting product for the high end market segments.

Here results on characterization of subcomponents as well as performance models for products and examples product developments are presented. This effort has created one new company and increased the sales for other involved companies. All in all the work within this thesis covers many aspects of applied photovoltaics, and progress within all the presented fields is demonstrated.