Photovoltaic (PV) panel installations in buildings and transportation hubs pose additional safety challenges as the glare from the panels can impose adverse impacts like flash blindness in human eyes. This study substantiates that polymer encapsulated thin film modules offer significantly low glare levels that are essential for building integrated and transport hub installations. In this work, the glare hazard potential associated with matt ethylene tetrafluoroethylene (ETFE)-based polymer sheet used as the frontsheet for the production of flexible thin amorphous silicon (a-Si) PV modules is studied and compared with standard PV glass used in crystalline silicon (c-Si) PV panels. The specular reflectance extracted from the measured total and diffuse reflectance for an angle of incidence (AOI) of 8° and the angular intensity distribution (AID) of specular reflectance measured for AOI ranging from 10° to 80° are utilized for glare assessment of the frontsheets. The mean value of specular reflectance extracted from the measured total and diffused reflectance is as low as 0.5% for the polymer frontsheet and is 4% for glass. The AID measurements suggest that the reflection from the polymer frontsheet is highly diffusive in nature in contrast to glass and the measured specular reflectance is always close to a magnitude lower than that from glass for all AOI. With the increase in AOI, the specular AID reflectance increases exponentially for glass to become as high as 40%, which is almost 20 times less than that from the polymer frontsheet for an AOI of 80°. Further, the c-Si test structure with glass and thin a-Si PV module with matt ETFE-based polymer as frontsheet showed similar specular reflectance trends as that of glass and the polymer frontsheet, respectively.

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Surface textures that result in high optical yields are crucial for high efficiency photovoltaic (PV) devices. In this work three different texturing approaches are presented that result in smooth concave structures devoid of sharp features. Such features can sustain the crack-free growth of device quality nano- to poly-crystalline materials such as nano-crystalline silicon, perovskites or C(I)GS, facilitating routes towards hybrid multijunction PV devices. A sacrificial implanted poly-c-Si layer is used to develop a random surface texture for the first texturing approach (Tsac). The influence of the processing conditions, such as layer thickness, implantation energy, dose and ion type, annealing time and temperature, of the sacrificial layer on the developed surface features is investigated. Additionally, a photolithographically developed honeycomb texture (Thoney) is presented. The influence of mask design on the honeycomb features is discussed and a relation is established between the honeycomb period and crack formation in nano-crystalline silicon layers. The reflective properties (spectral reflection, haze in reflection and angular intensity distribution) of these approaches are characterized and compared to a third texturing approach, Tsp, the result of chemically smoothened pyramidal <111> features. It was demonstrated that high optical scattering yields can be achieved for both Thoney and Tsp. Additionally, the performance of a-Si/nc-Si tandem devices processed onto the different textures is compared using both optical device simulations and real device measurements. Simulations demonstrate strong improvements in Jsc-sum (≈45%), in reference to a flat surface, and high Voc*FF of over 1 V are demonstrated for Tsp.@en

This work focuses mainly on development of modulated surface texturing of Al substrate for thin-film, silicon-based, flexible solar cells. We compared the current roll-to-roll process at industrial level with a newly developed lab-scale texturing that offers better performance both with KOH and NaOH etching of Al foil. The kinetics of these etching chemicals, modelled with an Arrhenius equation, is evaluated in both methods, activation energy and pre-exponential factor are calculated depending on etching concentration. We also deployed a new roll-to-roll experiment that shows better optical properties than the baseline. Finally, we also show the first results of micromorph tandem devices on the baseline texturing.

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