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Photovoltaic (PV) technology is necessary for global decarbonization. However, one of the challenges of the technology is that its land use may conflict with other space demands. Building-integrated photovoltaic (BIPV) is a solution to efficiently use the space and produce electricity with low CO2 emissions where it is needed, even when it is installed in inadequate orientations. Nonetheless, this technology needs a number of requirements as well as innovative solutions.First, we investigated the significance of installing PV from a carbon intensity (CI) perspective in sub-optimal orientations by comparing the CI values calculated for PV to the CI of European countries' electricity mix. We discovered that in most European countries, integrated PV in façades (including N-facing PV façades, which receive only about 15% of the insolation of an optimally oriented surface) would work as CO2 sink by reducing the green-gases emission compared to the electricity mix. This suggests that PV could be installed on most buildings regardless of their orientation, and even colored PV, which would, on one side, penalize the CO2 emissions, but on the other side, increase acceptability and market attractiveness, offers a promising dual benefit.Architects and building owners may prefer greater flexibility in terms of size, shape, and color, as it results in improved aesthetics. We focused on black metallic interconnects because they play a significant part in the uniform appearance of BIPV modules. We designed and manufactured an unique prototype equipment capable of self-aligned masking of metallic interconnects with ink regardless of their shape, size, or orientation. The designed manufacturing step can automatically produce fully black PV modules while only reducing the maximum power output by 2%.We designed and implemented a stability testing protocol for inks to be applied inside PV modules in glass/glass and glass/backsheet configurations. An ultraviolet (UV) curable-inkjet-ink showed large color change after UV accelerated aging caused by photodegradation of the main component of the ink, 2-phenoxyethyl-acrylate. Despite the color shift, PV module performance remained nearly stable, with less than 3% power loss after 360 kWh/m^2 of UV light exposure. We suggest a mitigation strategy based on the use of UV blocker encapsulants.Finally, an innovative color characterization technique appropriate for BIPV modules or any application in which the color layer is hidden behind a transparent material has been developed. The newly developed characterization technique surpassed benchmark techniques, including a portable colorimeter and an integrated sphere spectrometer to measure color behind a transparent cover. Without the transparent glass covering, all devices produced equivalent results. However, when a glass layer is above the colored layer, the novel colorimeter decreases the change in color from 57 (portable colorimeter) to 3 for an ivory colored glass laminate, obtaining better results.In essence, this thesis links together the complex issues surrounding BIPV and the incorporation of black metallic interconnects into PV modules, covering topics from equipment manufacturing to the stability of the inks, besides investigating advanced characterization techniques for real-world use. By doing so, this research offers valuable insights into the challenges associated with introducing novel components into the bill of materials of PV modules.
Christophe Ballif, Alessandro Francesco Aldo Virtuani, Ebrar Özkalay
Christophe Ballif, Alessandro Francesco Aldo Virtuani, Alejandro Borja Block