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Potential glare through reflected sunlight can be a significant hindrance factor for PV installations, especially for building-integrated photovoltaics (BIPV) with atypical orientations and tilt angles present. Structured glass surfaces or antireflective (AR) coatings are often used as a solution, however there currently is no universally recognized method or metric for estimating their impact on glare. This work presents an evaluation of the glare potential of different surface glasses for use in PV modules based on their bi-directional reflectance distribution functions (BRDF). BRDF threshold values for retinal burn damage, flash blindness and discomfort glare are calculated based on retinal irradiance thresholds from literature. Subsequently, gonioreflectometric measurements on PV mini-modules are used to characterize the reflectance profiles of eight different glass surfaces. Results for all measured structured glasses, both satinated and macro-textured, show significant reductions in BRDF compared to smooth glass, largely eliminating the potential for flash blindness as well as discomfort glare at low incidence angles. At high incidence angles, increased potential for discomfort glare as well as forward scattering along the glass surface can be observed. AR coatings, however, are shown to be insufficient to eliminate glare causing flash blindness.

Satinated glass is an increasingly important component of PV modules, especially in the building integrated (BIPV) sector, where it can contribute to more uniform appearance as well as significantly reduce the risk of glare. Different satination methods, such as wet chemical etching or mechanical abrasion, are available, which can impact the PV-relevant optical parameters in different ways. In order to characterize the associated performance losses, in this study eight different satinated glass types are compared in terms of spectral transmittance, surface morphology, relative transmission loss and angular dependent reflection losses. Measurements show only insignificant transmission losses of < 1 % for acid-etched glass compared to reference PV glass at normal incidence, with significant gains at high incidence angles > 60°. No significant differences between different acid-etched samples can be observed, all featuring homogeneous appearance. Other satination technologies, such as sandblasting or laser-etching show significantly higher transmission and reflection losses at low incidence angles, making them less viable for use in PV applications.

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.

Electroluminescence (EL) imaging is a photovoltaic (PV) module characterization technique, which provides high accuracy in detecting defects and faults, such as cracks, broken cells interconnections, shunts, among many others; furthermore, the EL technique is used extensively due to a high level of detail and direct relationship to injected carrier density. However, this technique is commonly practiced only indoors - or outdoors from dusk to dawn - because the crystalline silicon luminescence signal is several orders of magnitude lower than sunlight. This limits the potential of such a powerful technique to be used in utility scale inspections, and therefore, the interest in the development of electrical biasing tools to make outdoor EL imaging truly fast and efficient. With the focus of quickly acquiring EL images in daylight, we present in this article a drone-based system capable of acquiring EL images at a frame rate of 120 frames per second. In a single second during high irradiance conditions, this system can capture enough EL and background image pairs to create an EL PV module image that has sufficient diagnostic information to identify faults associated with power loss. The final EL images shown in this work reached representative quality SNR AVG of 4.6, obtained with algorithms developed in previous works. These drone-based EL images were acquired with global horizontal solar irradiance close to one sun in the plane of the array.

In this paper, we present a study of daylight EL acquisition and the results of a sunlight variation study in a scenario necessary to assure the increase of EL image quality with denoising by averaging for the robustness of the drone system whenbright and intermittently cloudy days occur. It was verified that the indicator of image quality based on the signal-to-noise ratio of EL images has a linear behavior with the amount of averaged images when there is no sun variation. When there are sun irradiance variation, it is observed that the quality decrease even with the increased number of images being averaged, turning to increase again only with further additional images.

The aim of this work is to compare angle of incidence (AOI) measurement setups for solar cells between laboratories with such capability. For the first time, we compare relative light transmission measurements among eight laboratories, whose measurement techniques include indoor and outdoor methods. We present the relative transmission measurements on three 156 mm x 156 mm crystalline-Si (c-Si) samples with different surface textures. The measurements are compared using the expanded uncertainties provided by each laboratory. Five of the eight labs showed an agreement better than ±2% to the weighted mean between AOIs from -75° to 70°. At AOIs of ±80° and ±85°, the same five labs showed a worst case deviation to the weighted mean of -3% to 5% and 0% to 18%, respectively. When measurement uncertainty is considered, the results show that measurements at the highest incidence angle of ±85° are problematic, as measurements from four out of the six labs reporting uncertainty were found non-comparable within their stated uncertainties. At 85° AOI a high to low range of up to 75% was observed between all eight laboratories.

As outdoor electroluminescence is implemented in the field, with several developments for automated inspection, an increasing concern rises upon the limitation that the electrical connections will bring to the inspection speed. In the effort to avoid both electrical contact and time limitations for PV inspections, here we present the progress in scaling up the well-known cell level photoluminescence imaging to a module level. The final goal is to build up a system that can perform PL excitation and image acquisition from the distance on PV modules and brought easily to the field by unmanned aerial vehicles (UAV).

Regular photovoltaic (PV) system inspections have become a challenge with the significant growth in the number of modules and peak power capacity of PV installations. Image acquisition using drones, based on visual, thermographic, and more recently luminescence, can be a viable solution for large-scale PV inspections. As luminescence can provide a highly detailed and accurate PV module failure diagnosis, the development of a daylight electroluminescence (EL) imaging capability is of high importance. EL imaging performed in the field during the day requires the enhancement of the relatively weak luminescence signal over the noise from the sun. This is accomplished by image averaging and background subtraction, which requires the highly accurate registering of the of individual module images. A sequential EL image acquisition at high frame rates in continuous motion at different angles will be the realworld situation for a drone-based PV inspection in daylight, and to account for this movement while maintaining high quality images, several image processing steps must be developed. With this motivation, here we describe and perform EL image processing on a module with different faults to assure quality of the EL images in different motion speeds.

The goal of this work is to perform outdoor defect detection imaging that will be used in a fast, accurate and automatic drone-based survey system for PV power plants. The imaging development focuses on techniques that do not require electrical contact, permitting automatic drone inspections to be perform quicker and with less manpower. The final inspection method will combine several techniques such as, infrared (IR), electroluminescence (EL), photoluminescence (PL), and visual imaging. Solar plant inspection in the future can be restricted only by imaging speed requirements, allowing an entire new perspective in large-scale PV inspection.

Impedance spectroscopy (IS) has been used for laboratory characterizations of photovoltaic (PV) technologies under well controlled conditions. This work applies IS for outdoor characterization of PV panels, in order to observe the effect of irradiance (G) and temperature (T) on the PV module’s impedance spectrum, and further construct an impedance model that can link environmental changes to the model’s parameters. To achieve this, an optimized setup has been developed for long-term impedance spectra monitoring synchronised with accurate irradiance and temperature data. Preliminary results show clear correlation between the determined parameters and ambient conditions.

PV-powered lighting systems, light to light systems (L2L), offer outdoor lighting where it is elsewhere cumbersome to enable lighting. Application of these systems at high latitudes, where the difference in day length between summer and winter is large and the solar energy is less requires smart dimming functions for reliable lighting.In this work we have build a laboratory to characterize these systems up to 200 WP from “nose totail” in great detail to support improvement of the systems and to make accurate field performance predictions.

Masteroppgaven består av en grundig detaliert balanseanalyse av den maksimale effektomformingsgraden (PCE) som kan oppnås med fargede enkeltlags solceller (SJSCs) og solceller med mellombånd (IBSCs). Arbeidet er basert på tidligere arbeid med detaliert balanseanalyse av IBSCs av Linge og optimalisering av fargede tandem solceller av Pearce et al. Disse blir først beskrevet, sammen med grunnleggende prinsipper for solcelle-fysikk, den detalierte balansemodellen, tredje generasjons solceller, fargevitenskap og fargede fotovoltaiske (PV) teknologier. Den detalierte balansemodellen for SJSCs og IBSCs er blitt validert, og kjøretiden til koden er blitt akselerert ved hjelp av tilnærmelser og forenklinger, inkludert en ny MPPT-algoritme for IBSCs. Refleksjonsspekteret er introdusert i modellen for å ta hensyn til fargede ugjennomsiktige solceller. Det utviklede programmet er blitt brukt til å beregne maksimal PCE, optimale båndgap og beste rektangulære refleksjonsspekter for SJSCs og IBSCs med fargene fra Macbeth ColorChecker-kartet. Optimaliseringen av SJSCs gjenskaper resultatene som tidligere er rapportert av Halme et al. Resultatene for IBSCs rapporteres for første gang i denne avhandlingen og sammenlignes med resultatene for SJSCs. Både de fargede SJSCs og IBSCs har en effekttap på mindre enn 12% for alle unntatt 3 farger fra Macbeth ColorChecker-kartet, med en lineær reduksjon i PCE-grensen som funksjon av relativ lysstyrke for lave verdier av sistnevnte. Videre er repetisjonsevnen til optimaliseringsalgoritmen studert. Til slutt er de utviklede modellene for SJSC og IBSC brukt til å beregne maksimal PCE og optimale båndgap for solceller med refleksjonsspekteret til MorphoColor solcellemodulkonseptet. Refleksjonen til MorphoColor-konseptet medfører et effekttap på 7-8% sammenlignet med en svart celle, både for SJSC og IBSC, og dobbelt så stort som effekttapet for det optimaliserte rektangulære spektret. The master thesis consists of the detailed balance analysis of the maximum PCE achievable with coloured single junction solar cells (SJSCs) and intermediate band solar cells (IBSCs). The work is based on previous work on detailed balance analysis of IBSCs by Linge and on coloured tandem solar cell optimization by Pearce et al. These are first described, together with the fundamentals of solar cell physics, the detailed balance model, third generation solar cells, colour science and coloured photovoltaic (PV) technologies. The detailed balance model for SJSCs and IBSCs has been validated, and the code runtime has been accelerated based on approximations and simplifications, including a new MPPT algorithm for IBSCs. The reflectance spectrum has been introduced in the model to account for coloured opaque solar cells. The developed program has been employed to calculate the maximum efficiency, optimum bandgaps and best rectangular shaped reflectance spectra, for SJSCs and IBSCs with the colours of the Macbeth ColorChecker chart. The optimization of the SJSCs reproduces the results previously reported by Halme et al. The results for IBSCs are reported for the first time in this thesis and compared to those of the SJSCs. Both the coloured SJSCs and IBSCs present a power loss smaller than 12% for all but 3 colours of the Macbeth ColorChecker chart, with a linear decrease in efficiency for low relative luminosity. Apart, the repeatability of the optimization algorithm has been studied. Finally, the developed models for the SJSC and IBSC have been employed to calculate the maximum PCE and the optimal bandgaps for solar cells with the reflectance spectrum of the MorphoColor solar module concept. The reflectance of the MorphoColor concept produces a 7-8% power loss with respect to a black cell for both the SJSC and IBSC, doubling the loss caused by the optimized rectangular-shaped spectrum.