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This paper introduces an innovative concept for active wall-curtain façade modules aiming at high level of energy autonomy. The façade module consists of two opaque panels and one transparent panel integrating building integrated photovoltaics supported by façade integrated battery Peltier air-conditioning unit, active shading, and LED lighting. The developed demo-protype was deployed at testing facility and subjected to long-term experimental monitoring to assess the energy performance in real environment. The complex monitoring system captured key power and thermal fluxes, temperatures, mass flows and other operational states of the active wall-curtain façade modules. These measurements were assessed in form of monthly overview depicting total electricity consumption, on-site energy production, heating and cooling delivery as well as self-sufficiency and self-consumption indicators. [ABSTRACT FROM AUTHOR]

The authors optimized the thickness of the layers in the 1.67‐eV‐bandgap‐perovskite sub‐cell of a 2‐terminal perovskite/silicon monolithic tandem solar cell under standard test conditions to get the current matching between the top and the bottom sub‐cells. Based on that optimized structure of the tandem cell, we characterized, calculated, and analyzed the annual output energy and the annual efficiency of the tandem cells on the facades and the rooftop of buildings under realistic conditions composed of module temperature, realistic illumination irradiance, and incident angle directly measured in Gifu, Japan in 2015. Consequently, the obtained annual output energy is 279.52, 238.89, 129.99, and 115.21 kWh/m2 with the corresponding annual efficiency of 22.42%, 19.70%, 10.50%, and 9.19% for the tandem solar cells mounted on the rooftop, the south, east, and west facades of the buildings, respectively. Thus, the rooftop and the south face of the buildings are the preferred directions for the BIPV application to gain higher energy. [ABSTRACT FROM AUTHOR]

• Electrical-thermal modeling of power converter as part of a BIPV library in Modelica. • Power converter integration in BIPV module frame in a 'plug and play' configuration. • Experimental validation using a converter prototype tested in a climate chamber. • Improved accuracy compared to TRNSYS power conditioner across all KPIs. • Converter placement inside the frame strongly a?ects the components temperature. European legislation on building performance and energy efficiency pushes the shift towards minimizing the environmental footprint of buildings. Building-integrated photovoltaics (BIPV) is a promising technology that can accelerate the transition to energy-neutral buildings. Quantifying the potential of BIPV is crucial and one means of obtaining those results is through simulation. The state-of-the-art tools offer either thermal or electrical specialization; in particular, balance of system components (BOS) such as power converters have not been studied in detail within the building simulations BIPV domain. In this paper, a multi-physics model of a BIPV integrated DC/DC converter is developed in the Modelica language, taking into account the thermal and electrical couplings inherent to power electronic systems. The model has been validated using representative outdoor BIPV measurements and a DC/DC converter prototype. It has been found that the proposed model provides reasonable accuracy and outperforms an equivalent power conditioning model in TRNSYS. To demonstrate the model's functionality, two case studies are performed. First, the temperature-dependence of the converter's efficiency and losses is quantified and analyzed and, second, the prominent contributors to the converter losses are identified and discussed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Rh/v is defined to estimate the potential of solar energy on the vertical area. • Sun-tracking PV shading elements integrated with windows are modeled and analyzed. • Novel optimum sun-tracking methods and cell layout are first proposed. • Annual energy generation and average efficiency are improved by 27.40% and 19.17%. • Optimum sun-tracking methods reveal great ability to protect glare from the sun. Abstract Vertical space bears great potential of solar energy especially for congested urban areas, where photovoltaic (PV) windows in high-rise buildings can contribute to both power generation and daylight harvest. Previous studies on sun-tracking PV windows strayed into the trade-off between tracking performance and mutual shading, failing to achieve the maximum energy generation. Here we first build integrated models which couple the performance of sun-tracking PV windows to the rotation angles. Secondly, one-degree-of-freedom (DOF) and two-DOF sun tracking are mathematically proven to be not able to gain either maximum power generation or non-glare daylighting under reasonable assumptions. Then we derive the optimum rotation angles of the variable-pivot-three-degree-of-freedom (VP-3-DOF) sun-tracking elements and demonstrate that the optimum VP-3-DOF sun tracking can achieve the aforementioned goals. When the restriction of the proposed model is relaxed, the same performance can be achieved by the optimum one-DOF sun tracking with extended PV slats and particular design of cell layout, requiring less complicated mechanical structures. Simulation results of nine global cities show that the annual energy generation and average module efficiency are improved respectively by 27.40% and 19.17% via the optimum VP-3-DOF sun tracking over the conventional perpendicular sun tracking. The proposed optimum sun-tracking methods also reveal better protection against sun glare. The optimum VP-3-DOF sun tracking is also demonstrated to be applicable to horizontal PV windows, as those applied in the sun roof of a glass greenhouse. [ABSTRACT FROM AUTHOR]

This study investigates a naturally-ventilated photovoltaic (PV) façade for high-rise buildings by conducting simulation study. Computational fluid dynamics (CFD) approach was adopted for modelling the temperature and airflow distributions around the naturally-ventilated and conventional PV facades of a case building. The simulation results show that the surface temperature of the naturally-ventilated PV façade is obviously lower than that of the conventional PV facade. The PV cell efficiency of the naturally-ventilated PV facade with different tilt angles was calculated by using simulation results and was found to be higher than conventional PV façade. This paper proved that in comparison with conventional PV facade, the naturally-ventilated PV facade can achieve lower surface temperature of the PV module and thus improving its power generation efficiency. However, experimental study and economic analysis still need to be carried out in future for wider application of the naturally-ventilated PV facade. [ABSTRACT FROM AUTHOR]

China's building stock of more or less uniform residential blocks requires energy-, comfort and not at least architectural upgrade, if future demands are to be met and if demolition and thereby loss of valuable resources is to be prevented. Replacement of these buildings is not an option since affordable housing continues to be required in Chinese cities. Comfort requirements are currently increasing from previously undemanding behaviour to more energy-demanding comfort expectations. Retrofit of conditioning equipment in old buildings will lead to a significant increase in energy consumption, if the buildings are not upgraded (insulated, air tightened, etc.). Furthermore, although China is leading in the production of photovoltaic modules, the utilization of building integrated photovoltaic systems (BIPV) is not yet implemented at a significant scale. However, the prevailing building typology is characterized by a southerly orientation, a favourable floor-to-roof ratio, a rather simple building envelope, appropriate floor plans and not at least a roof structure able to carry PV systems. Climates in many areas in China are more favourable for solar energy generation than in other countries, such as Germany, where BIPV is already widely utilized. This paper investigates the potentials of energy upgrade of a building typology representative for a large percentage of the existing Chinese building stock for 26 climates in China. Strategies of “efficiency” (energy-upgrade measures), “consistency” (renewable energy generation and revitalisation of existing structures) as well as “sufficiency” (reduced comfort requirements) are discussed as the pillars of a strong concept for sustainable upgrade of China's existing building stock. [ABSTRACT FROM AUTHOR]

Abstract: The shading-type BIPV claddings can act as power generators as well as external shading devices and insulation panels. There is little available information about the impacts of orientations and inclinations on the combined energy effects of the shading-type BIPV claddings, including the power output of PV modules, the cooling load reduction of windows and concrete walls. It is worth studying the effects of different shading-type BIPV cladding designs on the total energy saving in order to maximize the system’s energy performance. By considering the meteorological conditions in Hong Kong, the energy effect of the shading-type BIPV claddings with different surface azimuth angles, in terms of electricity generation and cooling energy consumption reduction is analyzed in this paper. Based on the investigations, the optimum design of the shading-type BIPV claddings for different orientations can be achieved. [Copyright &y& Elsevier]

[Display omitted] In this manuscript we review research on the feedback mechanisms between photovoltaic energy production and the urban environment, with an emphasis on synthesizing what is known, while drawing attention to limitations, and indeed errors in, the literature on this topic. We include in our analysis studies on photovoltaic (PV) systems in urban settings – on buildings, as shade structures, or as stand-alone arrays within an urban environment. We further limit the review to studies that investigate how the urban setting affects the performance of PV systems or how PV systems affect their surrounding urban environment. Our review is based on a systematic search of the literature, which revealed 116 unique articles that addressed the underlying questions in a meaningful way. While there are conflicting results reported across this body of literature, our review and synthesis reveal two key findings: (1) PV can significantly warm the city during the day, provide some cooling at night, and potentially increase energy use for air conditioning of buildings in some climates and building types; and (2) placing PV in an urban setting can adversely affect PV efficiency, reducing overall power production up to 20% in comparison to PV applications in rural settings. It is recommended that future developments of PV technologies focus both on increased efficiency and the need to increase reflection of wavelengths of energy not converted to electricity by the PV cells. Furthermore, designs for urban PV systems should explicitly consider the effects of elevated urban temperatures, pollution, and shading on system performance. [ABSTRACT FROM AUTHOR]

This paper reviews and analyzes technological design options, which have become available to date for BIPV systems on roofs and facades, independently of specific products or building projects. This means that this survey does not analyze existing products or realized buildings, but provides an overview of the technologies for BIPV. The starting point is an analysis of the relevance of BIPV technologies for the decarbonization of energy systems, providing energy for direct use of electricity and sector coupling together with an analysis of the German BIPV market. The paper presents the wide range of technical design options for BIPV systems and categorizes and analyzes them to provide a structured overview. This comprises a detailed analysis of the design options for BIPV modules, in which not only the design options for the PV cell layer were comprehensively investigated, but also the different variants of embedding materials, front and rear cover materials, additional interlayers and electrical module layout. Two fundamental module-level design options were investigated in particular detail: The use of PV cells as basic elements of patterns and the use of color to conceal the PV cells. Subsequently, options for the design of complete electrical systems are reviewed, ranging from sub-module level design parameters to building energy systems. Design options for the constructional integration of BIPV modules in the building envelope complete the review of technological design possibilities. [ABSTRACT FROM AUTHOR]