The built environment is among the highest energy consuming sectors worldwide. However, buildings have large surface areas that can be used to improve the building energy performance. One example is by integration of photovoltaic systems in roofs and facades, which can reduce the carbon footprint of the built environment. An emerging field that could lead to energy savings involves the glazing. Switchable or smart windows allow for a variable transparency which affects the amount of incoming daylight and solar heat. Manually controlled smart windows however, require electricity to function and could thus be powered by solar energy to function autonomously. Smart windows have been shown to improve the building energy performance by reducing heating, cooling and lighting loads and can also be used to optimize the visual and thermal comfort conditions of occupants. In this thesis project the energy performance of three types of switchable glazing has been compared to different window technologies including electricity generating photovoltaic windows. Additionally, the hourly and yearly electricity requirements of each smart window and the corresponding minimal photovoltaic system requirements have been determined.

The advancement of innovative PV technologies has led to an all-time high integration of the same in the urban environment. Furthermore, development of decentralized power systems complements this rise as it supports in-situ power consumption. Due to space availability constraints in urban environments and a need for appealing aesthetics, tailored PV modules is gaining importance. However, it is desirable to achieve maximum power out of these tailored PV modules to ensure efficiency in space usage.
Literature suggests that one of the most apt performance metric for estimating the goodness of design for PV modules is the CTM ratio. However, various challenges incurred upon implementing the present CTM analysis algorithms on tailored PV modules suggests the need for development of a different approach to estimate the same. The presented work strives towards the development of a tool for the prediction of various performance metrics, including the CTM ratio, of both standard and tailored PV modules to aid its user to make educated design choices to develop optimum modules.
The methodology used for development of the tool encompasses various steps which occur in a pre-programmed flow. Firstly, a developed script automatically creates the module structure based on user inputs. Hereafter, ray tracing is implemented and its results furnishes optical performance of the module. Furthermore, an electrical loss calculation model is developed, using differential element method, which when coupled with the optical performance data enables the estimation of the CTM ratio and other performance metrics. The tool is programmed in Matlab to ensure easy integration of the same with the PVMD toolbox for future research on module designs.
Firstly, an attempt is made to optimize the parameters of the mini-module for maximizing its performance. For a white backsheet test mini-module, optimization through the usage of the tool, leads to a 5.52 % gain from the worst case design. This gain is realized by achieving an optimal tuning between the cell-cell and cell-edge spacing. Moreover, when compared, the white backsheet module’s power production capacity outperforms the black backsheet module by around 13.93 %. Additionally, effect of busbars on the performance of the module is investigated.
Furthermore, the tool is able to derive novel empirical formulas which, for different module architectures, predict the effect of cell top metallization on the cell photocurrent density in an encapsulated environment.
Secondly, efficacy of the tool is demonstrated for a comparative study between a 60 cell module and its corresponding 120 half-cut cell module. The tool suggests the half-cut cell module to have a 2.91 % gain in CTM ratio as compared to its full cell counterpart.
Thirdly, the tool demonstrates modelling and simulation of glass-glass modules and achieve optimization. The tool also recommends an increase of the dimension size for the test module to 20×20 cm2 to achieve the exemplary target transmission of 14 %.
Lastly, the tool efficacy is demonstrated for a triangular PV module. This module with a white backsheet is found to outperform its black backsheet counterpart by 9 % in CTM ratio.

While there are many factors influencing the efficiency of photovoltaic (PV) cells one of the most important ones is temperature. Module temperatures can get significantly higher than the ambient temperature, increases of up to 30°C have been reported in literature. An increase in temperature has an adverse effect on the module’s efficiency, literature has reported a drop of 0.40−0.65%/°C. Therefore, it is not uncommon that during warmsunny days PVmodules operate at a much lower efficiency than advertised by the manufacturer. Different methods of thermal management can be applied. In this research, the effect of phase change materials (PCM) to passively lower the operating temperature of PV panels was studied. During the phase change of a material heat is absorbed as latent heat instead of sensible heat, this does not cause the temperature of the material to increase. Using this process a PCM can keep a relatively stable temperature until it has completely changed its phase. This can be utilised by placing PCM behind a PV module, so that the heat generated in the panel can be absorbed by the PCM while remaining at a stable temperature. The scope of this research was to performmeasurements with a PV-PCMsystem under real weather conditions. Additionaly, a thermalmodel was build using ComsolMultiphysics, to make predictions for the optimal PCM parameters. This thermalmodel was validated with the results from the measurements. Measurements for a free rack situation showed surprisingly a slight increase in temperature of the PVPCM module compared to a reference PV module. Most likely due to convective cooling caused by the wind. And indeed, after installing insulation material at the back of the modules to emulate building integrated photovoltaics (BIPV) a significant decrease was found. For a two week period of measuring a −6.69°C temperature reduction was found, with a peak difference of −21.7°C. This resulted in an energy yield increase of 2.8% compared to the reference panel over this period. From this work, it can be concluded that PCM thermal management is not advisable for free standing modules due to the large influence of convective cooling caused by the wind. However, this method of thermal management can have significant benefits in BIPV situations where convection is not relevant.

Whilst research in solar cell materials lead to higher efficiencies every year, new difficulties arise with every breakthrough to get an even higher efficiency. Therefore, every component of a PV system should be examined, as well as how their behaviour under operation affects performance to improve the overall PV yield. In particular the temperature of a module can have a negative impact on the power output. The drop in power output is a consequence of a negative thermal coefficient that results in a decrease of open circuit voltage with increasing temperature. For silicon solar cells, efficiency drops of 0.4-0.65%/°C have been reported in literature. Moreover, daily repetition of temperature cycles can cause mechanical degradation, thereby decreasing the lifetime of PV modules. In this thesis, phase change materials (PCM) have been studied as a method to passively reduce the operating temperature of PV modules. This is based on the ability of materials to stay at a relatively stable temperature during a phase change. By placing a PCM at the back of a PV module, the temperature difference between the module and the melting PCM causes a thermal gradient, resulting in conduction of heat away from the
module. In order to find the optimal properties of a PCM, a thermal model was first developed in COMSOL Multiphysics and benchmarked with field measurements from literature. Simulations for Rotterdam, the Netherlands, revealed that an optimized PCM could increase the yearly electrical yield by 1.23% for a rack-mounted module, or 3.52% for a roof-mounted module. Furthermore, measurements were performed with commercially available PCMs under a Large Area Solar Simulator (LASS). These were able to reduce the average module temperature by 30-36°C, albeit under heavy infrared radiation coming from the simulator.

Building Integrated Photovoltaics (BIPV) has the potential to play a major role in the ongoing transition towards nearly zero energy buildings. However, the BIPV market is still a niche market, representing only 1% of the global PV share. One of the main barriers that hinder the deployment of BIPV is the lack of aesthetic flexibility. Architects and designers are often reluctant to embed PV systems in buildings due to their unsuitable color.
In this thesis, the use of interference filters (IFs) as color coating solution for PV modules is proposed. IFs are optical devices designed to selectively reflect a narrow portion of the visible solar spectrum while transmitting the remaining part. The structural coloration provided by the filter is highly dependent on the angle of incidence of the light. This angular dependence could be an issue for BIPV applications, since color homogeneity is often an important requirement. The objective of this work is to model, fabricate and assess the opto-electrical performance of colored crystalline silicon (c-Si) PV modules based on interference filters, with the final goal of increasing the aesthetics of this technology.
First, the angular resilience challenge is addressed. Simulation results show that texturing the glass surface significantly improves the color stability, thanks to diffuse reflection of light. Very high angular resilience up to 80º can be achieved with a double-side texture profile made of hemispherical grooves. Secondly, five interference filters deposited on different glass substrates are used to fabricate 10 x 10 cm² c-Si colored mini-modules. The optical characterization of the demonstrators
allows to partially validate the optical model and confirm the good angular resilience of the textured surfaces. Finally, the electrical performance of the mini-modules is evaluated. I-V measurements show that IFs only affect the short-circuit current of the mini-modules due to optical losses. Depending on the color and the topology of the surface, absolute efficiency losses range from 0,95% to 4,6%.