Façade building-integrated photovoltaics is a technology that transforms a passive façade into a distributed, renewable electrical generator by the inclusion of solar cells in the building envelope. Partial shading due to nearby objects is a typical problem for façade building-integrated photovoltaics as it strongly reduces the output power of the installation. Distributed maximum power point tracking by means of embedded converters and a common direct current bus has been proposed to alleviate this issue. However, the bus voltage plays an important role in converter topology selection and overall efficiency, although this is not being covered in literature. Also the influence of the solar cell technology on the output voltage of the module is not studied before, although it strongly influences the converter topology selection and the losses. In this paper, a methodology is described to investigate the influence of the voltage level and solar cell technology by taking conversion losses in the converters and the cabling into account. The methodology is applied to two case study buildings for which four different cell technologies are considered. It is shown that overall high efficiencies are obtained, regardless of the voltage level. However, the loss distribution changes significantly with the voltage. This aspect can be used advantageously to reduce thermal stresses on the embedded converter. Furthermore, the overall system efficiency is typically higher when the voltage step-up is lower.

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Currently, photovoltaic (PV) installations target a maximization of annual energy yield. However, as the grid penetration of PV is increasing, PV electricity generation will need to match better with local load profiles. Especially the seasonal variabilities remain challenging. While wind and PV tend to have complementary seasonal variability, wind turbine installation faces limitations especially in densely populated areas. In this paper, we discuss how this challenge may be addressed with climate- and consumption-specific PV module technology. In particular, we demonstrate how the temperature coefficient of a PV system can impact the energy yield throughout the year. In colder climates, higher temperature coefficients allow for a better energy balance, favoring production in colder seasons without a significant reduction of yearly energy yield. Simulations for locations at high latitude, and colder climates, indicate that higher temperature coefficients and improved low-light behavior not only enable a higher energy yield in cold seasons, but also negligible losses in the overall yearly energy yield compared to lower temperature coefficients and slightly better low-light behavior. Simulations show that these results can be obtained using commercial PV modules. More broadly, they indicate how PV module technology may be optimized depending on the location and climate.

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Building-integrated photovoltaics (BIPV) is seen as a key technology to reduce the environmental impact and net power consumption of buildings. The integration of PV into building components, such as façade, window, roof or shading elements, leads to a distributed generation over the building envelope with a profound impact on the electrical installation. Designing the electrical system with string inverters and a possible wide variety of module sizes and technologies is a challenging task. To overcome this issue, Module-Level Converters (MLCs) can be used. A supplementary benefit is that the consequences of partial shading can strongly be reduced. This paper investigates whether the current generation of MLCs is suited for embedment in facade BIPV modules. The PV output is categorized and compared to the input parameters of the converters. Besides the discrepancy between the physical dimensions of the converters and the desired installation location, thermal and electrical measurements on a prototype BIPV curtain wall element reveal that daily energy losses can be as high as 50% due to thermal overload when used in a moderate climate such as Belgium. The paper concludes by discussing further standardization of BIPV module-level converters.@en