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Rising global energy demand, particularly in the building sector, has catalyzed a shift toward sustainable building practices. Buildings are now being redefined from mere energy consumers to potential energy providers, with building façades offering extensive areas for solar installations. This paper reviews recent advances in Wall-Integrated Solar Energy (WISE) systems that produce heat and electricity. A detailed comparison of their structures and performance is provided for various WISE systems, including building-integrated photovoltaic/thermal (BIPV/T) systems, attached sunspaces, Trombe walls, solar thermal collectors (STCs), PV–Trombe, Bio–PV, etc. The goal of this review is to understand the capacity of these technologies to produce energy via walls. The review concludes with key findings and future recommendations, aiming to guide the sustainable evolution of the building industry. Data from the literature suggest that building walls can be a promising energy source with the appropriate integration of solar energy. [ABSTRACT FROM AUTHOR]

Photovoltaic solar energy has emerged as a vital solution in energy transition, especially in buildings with building-integrated photovoltaic (BIPV) systems. This study evaluated a BIPV system in João Pessoa, Brazil, using PVsyst 7.4 software for simulations in 2023 and experimental tests in 2024 to compare real and simulated energy values injected into the grid. The experiments were conducted in April, June, July, and August, covering seasonal variations. The east and west orientations showed the best performance, with annual production of 65.5 and 81.6 kWh, respectively, due to the balanced solar irradiance. Conversely, the north and south orientations generated less electricity, with 51.3 and 42.1 kWh, respectively, due to lower direct solar exposure. The average injected energy was 0.2445 to 0.2530 kWh/day in April, 0.2851 to 0.2470 kWh/day in June, 0.2816 to 0.2400 kWh/day in July, and 0.1556 to 0.1700 kWh/day in August. Performance ratios were 44.3% for the north, 44.4% for the south, 47.4% for the east, and 56.8% for the west, highlighting the impact of orientation. It is concluded that the east and west facades are more suitable for BIPV systems in João Pessoa, emphasizing the importance of local factors in optimizing urban energy efficiency. [ABSTRACT FROM AUTHOR]

Building-Integrated Photovoltaic (BIPV) systems, which seamlessly integrate solar photovoltaic components into building structures, have garnered widespread attention for their aesthetic appeal and energy efficiency. However, the promotion of BIPV systems has also raised new fire safety concerns. This paper reviews recent fire incident cases and conducts risk identification for factors such as building and environmental risks, photovoltaic systems, electrical equipment, and safety protection. A fire risk assessment is performed using the Analytic Hierarchy Process (AHP) to evaluate the overall fire safety of BIPV systems. Based on the assessment, corresponding safety design strategies are proposed to ensure the safety of buildings and occupants. The research results indicate that BIPV systems pose certain fire hazards, and that proper design and regulation are crucial to mitigate these risks. [ABSTRACT FROM AUTHOR]

As cities confront multiple challenges such as climate change, urbanization, and food security, growing attention has been given to sustainable vertical farming and renewable energy solutions. Building facades, typically underutilized in high-density urban environments, present an opportunity for multifunctional buildings composed of both photovoltaic (PV) systems and vertical farming modules. However, on vertical surfaces, these two systems often compete for space. This research focuses on the development of a multifunctional agrivoltaics building envelope (ABE) system, combining building-integrated PV (BIPV) technology with hydroponic vertical farming. This ABE system adopts a modular design approach, where each unit can be prefabricated independently and assembled through an interlocking connection design and bolted fastening to ensure ease of construction and scalability. The design process includes the development of 2D cross-sectional technical design, assembly sequences, and an analysis of key design parameters through 3D modeling. The research adopts a combined Research through Design (RtD) and Research for Design (RfD) approach to bridge prototyping, testing, and performance optimization. This research highlights the potential of integrating renewable energy with agricultural production in building envelope systems. By addressing space optimization and multifunctionality, the research provides a practical framework for future applications in urban sustainability. [ABSTRACT FROM AUTHOR]

Building-integrated photovoltaics (BIPV), a significant technological tool to reduce carbon emissions from buildings, have attracted extensive research attention worldwide as the call for “carbon neutrality” in the building sector continues to rise. Existing studies lack a comprehensive compendium of global BIPV-related research, and articles on the latest advances in the last five years are particularly scarce. Consequently, this study conducted a scientometric review of BIPV research to systematically and visually analyse the cutting-edge BIPV literature. Through multiple rounds of searching and screening, this study collected 467 BIPV-related studies between 2019 and 2023. It utilised CiteSpace to analyse the development of BIPV literature, summarise the themes, and predict the trends. The review reveals that the cross-disciplinary nature of the discipline dynamically shapes the focus of BIPV research. Based on the findings of scientometrics, three major themes are outlined and critically analysed: science and technology, market products, and implementation impediments. By comprehensively summarising and analysing the most recent BIPV literature, this study proposes a series of research trends in the field. This study provides policymakers, architects, and researchers in the field of low-carbon buildings with a detailed compendium of the current status and trends of BIPV. It offers specific insights and sources of reference for in-depth research and the promotion of the application of BIPV technology in the building industry.

Copper indium gallium selenide (CIGS)‐based solar cells are a type of thin‐film photovoltaic technology used to convert sunlight into electricity. They are one of the most promising thin‐film technologies with high efficiency and low‐cost potential. CIGS is a direct band gap material with a high absorption coefficient, around 2 µm thickness can absorb most of the light which can reduce the usage of material. CIGS solar cells have a better temperature coefficient, meaning their efficiency decreases less in high‐temperature environments compared to other solar technologies. Furthermore, CIGS solar cells also have excellent low‐light performance due to their broad absorption spectrum. This allows them to generate electricity even in partially shaded or cloudy conditions, which can be common in urban environments with tall buildings or trees casting shadows. Thus, CIGS solar cells are also a good option to be used for building‐integrated PV (BIPV) systems. The latest cell efficiency record was reached in 2023 with 23.6%. Ongoing research aims to increase efficiency, durability, and cost‐effectiveness, making the CIGS thin‐film technology a mainstream option for solar energy generation. [ABSTRACT FROM AUTHOR]

This paper presents a novel framework that integrates Conditional Generative Adversarial Networks (CGANs) and TimeGAN to generate synthetic Building-Integrated Photovoltaic (BIPV) power data, addressing the challenge of data scarcity in this domain. By incorporating time-related attributes as conditioning information, our method ensures the preservation of chronological order and enhances data fidelity. A tailored learning scheme is implemented to capture the unique characteristics of solar power generation, particularly during sunrise and sunset. Comprehensive evaluations demonstrate the framework's effectiveness in generating high-quality synthetic data, evidenced by a 79.58% improvement in the discriminative score and a 13.46% improvement in the predictive score compared to TimeGAN. Moreover, integrating the synthetic data into forecasting models resulted in up to 23.56% improvement in mean absolute error (MAE) for BIPV power generation predictions. These results highlight the potential of our framework to enhance prediction accuracy and optimize data utilization in renewable energy applications. [ABSTRACT FROM AUTHOR]

The deployment of renewable energy in the construction industry has emerged as a crucial topic due to the building sector's substantial energy consumption and greenhouse gas emissions. Building Integrated Photovoltaics (BIPV) offers a promising solution, replacing conventional building materials with solar energy-generating components. Moreover, retrofitting commercial buildings with BIPV and kinetic façades present an innovative approach to improve energy efficiency and enhance occupant well-being. Adaptive façades, capable of responding to varying climatic conditions, play a pivotal role in reducing energy consumption while ensuring thermal and visual comfort for occupants. By integrating solar generation and shading capabilities, BIPV kinetic façades deliver dual benefits, optimizing energy performance and reducing lifecycle costs, compared to traditional PV systems. Furthermore, effective daylighting strategies not only contribute to energy savings but also positively impact occupant productivity and comfort. Despite predominant research focusing on energy aspects, there is a notable gap in comprehensive assessments that integrate environmental, economic, and daylighting considerations. Therefore, evaluating Australian commercial buildings' energy and daylighting performance with BIPV kinetic façades provides valuable insights for advancing sustainable building designs and operations in the region. The implementation of kinetic BIPV façades in Melbourne reduced energy consumption by 18% and covered 26% of energy demand, achieving the target daylighting levels. [ABSTRACT FROM AUTHOR]

Featured Application: Improving the longevity of photovoltaics (PV) is essential in the TW solar age, especially towards their integration into urban infrastructure and for building components for city decarbonization. Despite continuous product changes, the physical triangle based on field observations, data analysis, and testing, and applicable from the nanoscale of solar cells to the kilometer scale of utility PV installations, has substantially improved PV reliability and lifespan to more than 30 years. Here, we present the progress in our scientific understanding of PV degradation processes, the influence of key factors, field and remote operation monitoring methods, approaches for improving PV longevity, and the scientific research needs that arise from the incomplete identification of these degradation processes. We propose appropriate mitigation strategies for enhancing the longevity of PV and building-integrated photovoltaics (BIPV), and we discuss the feasibility of achieving PV longevity values of 50 years by reducing the PV degradation rate to 0.2%/year. With the increase of photovoltaic (PV) penetration in the power grid, the reliability and longevity of PV modules are important for improving their payback period and reducing recycling needs. Although the performance of PV systems has been optimized to achieve a multi-fold increase in their electricity generation compared to ten years ago, improvements in lifespan have received less attention. Appropriate operation and maintenance measures are required to mitigate their aging. PV cells and modules are subject to various degradation mechanisms, which impact their long-term performance and reliability. Understanding these degradation processes is crucial for improving the lifetime and sustainability of solar energy systems. In this context, this review summarizes the current knowledge on key degradation mechanisms (intrinsic, extrinsic, and specific) affecting PV modules, as well as on-site and remote sensing methods for detecting PV module defects and the mitigation strategies employed for enhancing their operational lifetime under different climatic conditions in the global environment. [ABSTRACT FROM AUTHOR]

Urban surfaces such as rooftops, facades, and infrastructure offer significant potential for solar energy integration, contributing to energy efficiency and sustainability in cities. This article introduces an advanced multi-criteria assessment (MCA) framework designed to evaluate the suitability of various urban surfaces for solar energy deployment. The framework extends beyond traditional economic, environmental, and technological factors to include social, political, legal, health and safety, cultural, and psychological dimensions, providing a comprehensive evaluation of photovoltaic (PV) applications in urban contexts. By synthesizing existing literature and applying this holistic MCA framework, this research offers valuable insights for urban planners, architects, and policymakers, enabling strategic optimization of solar energy integration in urban environments. The findings underscore the importance of sustainable urban development and climate resilience, highlighting key factors influencing solar technology deployment and proposing actionable recommendations to address existing challenges. [ABSTRACT FROM AUTHOR]

With the increasing number of public buildings worldwide, their energy consumption has garnered significant attention. This study aims to promote building energy efficiency and emission reduction by exploring the application of Building-Integrated Photovoltaic technology in library retrofitting. Using a library in Changsha City as a case study, we conducted an energy consumption analysis of the building's envelope and identified the window section as the highest energy consumer. We proposed a novel improvement scheme—the sun-shading photovoltaic panel (which shades the sun while generating electricity). Additionally, we utilized the roof space for the installation of conventional photovoltaic panels. Simultaneously, the primary objective of this paper was to derive a renovation strategy for public buildings in regions characterized by high summer temperatures and low winter temperatures based on the renovation case of this library. This paper comprehensively investigates the length and angle of sun-shading photovoltaic panels facing different directions, as well as the azimuth angle, tilt angle, and installation spacing of the conventional photovoltaic panels on the roof. Two retrofitting schemes were proposed. Through simulation and comparison, the second scheme was found to reduce the annual electricity consumption by 1,233,354 kWh, achieving a 35.4% decrease compared to the original building. Using the Changsha library as a template for public buildings, this study provided a retrofitting approach with Building-Integrated Photovoltaic technology via DesignBuilder, which could be extended to other geographic locations. The results demonstrated the significant energy-saving effects of the proposed retrofitting scheme. [ABSTRACT FROM AUTHOR]

Building integrated photovoltaic (BIPV) windows impact building performance by balancing daylighting availability, visual comfort, solar power generation, and building energy consumption. Optimizing this balance is crucial for improving overall building energy efficiency and indoor environment quality. This study introduces a novel curved photovoltaic window design aimed at increasing daylight transmittance while maintaining the same photovoltaic area as a flat PV window. The annual daylighting availability, visual comfort and building energy performance of three types of flat/curved PV windows (180°, 120°, 0°-flat) in a reference office room was comparatively studied across five different climate zones in China (Xiamen, Harbin, Nanjing, Kunming, and Beijing). The PV model was validated by the experimental data. The results showed that the room with curved PV windows had significantly higher daylighting availability compared to flat windows, with the growth rates of the spatial useful daylight illuminance ranging of 3.94%–4.78% and 5.56%–5.94%, respectively, for the curved PV windows at central angles of 120° and 180° across different climate zones. The 120° curved PV windows achieved the lowest net energy used intensity (Net_EUI), suggesting the advantages of curved PV windows and proposed the existence of an optimal curvature for achieving the lowest Net_EUI. [ABSTRACT FROM AUTHOR]

The Italian industrial sector contains 22% of the final energy demand due to the poor energy performance of manufacturing buildings. This proposed study aimed to evaluate retrofit interventions for existing industrial buildings integrating photovoltaic solutions into the external envelope to improve both the environmental sustainability and the facade performance. The methodology is based on an innovative procedure including BIM and generative design tools. Starting from the Revit model of a representative case study, interoperability with energy analysis plugins via Grasshopper were exploited to optimize the differently oriented facade layout of photovoltaic modules to maximize the electricity production. In the case of comparable facade sizes, the building orientation had a minor impact on the results, although a southern exposure was preferable. The optimized configuration involved the installation of PV panels with a tilt angle ranging from −35° to −75°. The best compromise solution between the panel surface area and energy production during the summer solstice involves 466 m2 of PV modules. The design-optioneering approach was used to define possible alternatives to be explored for the possible installation of solar shading systems on existing windows. In this case, the impact on visual comfort within the working environment was chosen as a reference parameter, along with the value of the indoor air temperature. A decrease in this parameter equal to 0.46 was registered for the solution with horizontal (or nearly horizontal) shaders and a spacing ranging between 0.2 and 0.4. The integration of the BIM environment with generative design tools effectively assists decision-making processes for the selection of technological solutions in the building sector.

Semitransparent thin-film solar cells, especially those fabricated directly on building materials, have attracted much interest in the continuously increasing demands of building-integrated photovoltaic (BIPV) applications. Herein, radial junction (RJ)-structured hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, directly constructed upon silicon nanowires (SiNWs) grown by a vapor–liquid–solid (VLS) process on the rough surface of the tinplate substrates, have been successfully demonstrated. After optimizing the SiNW density, an efficiency of 5.89% can be achieved, with an average value of 5.38 ± 0.39%. Compared to the conventional thin-film photovoltaics on glass substrates, the semitransparent RJ-structured thin-film solar cells on the laser-cutting tinplate substrates have a lower reflectivity, an adjustable/designable light transmission, as well as excellent mechanical stability. More importantly, tinplate and other steel/metal substrates can be used as construction materials; thus, the overall costs, including fabrication and installation costs as well as the building construction cost, can be largely reduced. These results highlight the promising potential of the RJ thin film technology on laser-cutting steel/metal substrates to fabricate low-cost, low-reflection, and mechanically stable semitransparent thin-film BIPV devices. [ABSTRACT FROM AUTHOR]

The Italian industrial sector contains 22% of the final energy demand due to the poor energy performance of manufacturing buildings. This proposed study aimed to evaluate retrofit interventions for existing industrial buildings integrating photovoltaic solutions into the external envelope to improve both the environmental sustainability and the facade performance. The methodology is based on an innovative procedure including BIM and generative design tools. Starting from the Revit model of a representative case study, interoperability with energy analysis plugins via Grasshopper were exploited to optimize the differently oriented facade layout of photovoltaic modules to maximize the electricity production. In the case of comparable facade sizes, the building orientation had a minor impact on the results, although a southern exposure was preferable. The optimized configuration involved the installation of PV panels with a tilt angle ranging from −35° to −75°. The best compromise solution between the panel surface area and energy production during the summer solstice involves 466 m2 of PV modules. The design-optioneering approach was used to define possible alternatives to be explored for the possible installation of solar shading systems on existing windows. In this case, the impact on visual comfort within the working environment was chosen as a reference parameter, along with the value of the indoor air temperature. A decrease in this parameter equal to 0.46 was registered for the solution with horizontal (or nearly horizontal) shaders and a spacing ranging between 0.2 and 0.4. The integration of the BIM environment with generative design tools effectively assists decision-making processes for the selection of technological solutions in the building sector. [ABSTRACT FROM AUTHOR]

This paper examines the use of Phase Change Materials (PCM) in Building-Integrated Photovoltaic (BIPV) systems. To assess the performance of BIPV–PCM systems, the study employs a Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis. The study features the advantages of using PCMs with BIPV envelopes. The benefits include lower heating and cooling requirements, shifted peak loads and increased thermal comfort. However, there are several challenges like heat loss and lower energy efficiency which needs to be addressed. Further, the potential for reduced PCM efficiency over time is recognized. The paper concludes by recommending further research on alternative PCM placement strategies, enhanced PCM formulations, gypsum board integration and the evaluation of PCMs combined with nanoparticles. [ABSTRACT FROM AUTHOR]

Among renewable energy generation technologies, photovoltaics has a pivotal role in reaching the EU's decarbonization goals. In particular, building-integrated photovoltaic (BIPV) systems are attracting increasing interest since they are a fundamental element that allows buildings to abate their CO2 emissions while also performing functions typical of traditional building components, such as sealing against water. In such a context, since one of the main challenges to decarbonizing the building sector lies in the retrofitting of existing buildings, the current paper is focused on the design, development, and testing of a novel roofing BIPV system. The entire research was carried out as part of the Horizon 2020 HEART project. In more detail, the research analyzed the requirements of typical pitched tile roofs, which are currently the most common type in Europe, and developed a universal photovoltaic tile that can be easily and quickly integrated into such a type of roof. The research was also aimed at minimizing the embodied energy of the component and promoting disassembly and recycling at the end of life, fully in line with a circular economy perspective. The adopted design and development processes are described in detail in the present paper, along with the results of several tests performed in the field. In addition, further development prospects of the component, aimed at meeting the integration requirements in historic buildings, are finally presented. [ABSTRACT FROM AUTHOR]

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Organic photovoltaics (OPV) has attracted tremendous attention as a promising alternative to silicon wafer‐based technologies for building integration. While significant progress has been achieved on the power conversion efficiency of OPV technologies, their field stability is rarely studied. This work investigates the field performance and reliability of a large‐area OPV module designed for building integration in tropical Singapore for 4.5 years. The device suffered more than 14% degradation in power at the standard testing conditions from the initial performance, largely due to losses in fill factor (−12% relative). During the monitoring period, it exhibited comparable performance to more conventional silicon PV technologies, with an average specific energy yield of about 4 kWh/kWp/day and an average performance ratio of 0.96. Excellent performance at low light conditions was also observed. However, its field performance was heavily impacted by soiling, which typically led to a 5 to 10% loss in the current output after several months. Further, the device's outdoor performance also showed a three‐stage degradation process, including (1) an initial slow degradation in the first 2 years (about −1%/year), (2) a stable period with negligible performance loss from Years 2 to 3.5, and (3) a rapid degradation in the last year (about −5%/year). [ABSTRACT FROM AUTHOR]

Buildings significantly consume fossil energy, leading to substantial carbon emissions contributing to global warming and rising sea levels. These environmental impacts pose serious challenges, necessitating a shift towards sustainable building designs. By integrating clean energy solutions into building architecture, we can reduce the environmental burden of emissions. This approach mitigates adverse effects on living organisms and ecosystems and promotes long-term sustainability and resilience in urban development. Building-Integrated Photovoltaic (BIPV) systems represent one such approach for substituting fossil energy. However, implementing BIPV effectively necessitates comprehensive analysis considering numerous parameters and variables. This paper introduces building design strategies employing the BIPV approach. The decision-making process in designing alternatives utilizes parametric methods, recognized for their ability to yield optimization results for various variables through the development of design algorithms. The study focuses on the design of a studio building at the University of North Sumatra. Comparative analysis of the results obtained through parametric design aims to identify the most favorable design outcomes. The research includes developing a parameterized design algorithm, workflow, and assessment results for selecting optimal design alternatives. The results indicate that the placement of PV panels on the side area (PVOS) has more potential than placement on the top area (PVOT). Despite the PVOT area being observed to be 0.57% smaller than PVOS, PVOS shows a significant increase in total Incident Radiation (IR), average IR, and total Energy Generated by 137.14%, 128.40%, and 132.97%, respectively. [ABSTRACT FROM AUTHOR]