Use Of Building-integrated Photovoltaics Research Articles

Comparative analysis of steel bar structures of solar canopies composed of hyperbolic paraboloid units using genetic algorithms

Building integrated photovoltaics (BIPV) understood as an integral building component, is becoming more and more popular. In turn, the use of BIPV on curvilinear roofs is an interdisciplinary issue covering geometry, environmental engineering, architecture and construction. The article presents an approach to designing efficient steel bar structures of the modular solar canopies using genetic algorithms and their evaluation. Shaping effective forms of solar roofs was subordinated to the idea “form follows environment” in the original way as the roof form, and thus the shape of the structure depended on the amount of solar energy absorbed by the roof surface. The structures designed on a regular polygon plan were created from three, four, five, or six hyperbolic paraboloid (HP) modules arranged radially. Algorithmic definitions of their forms made it possible to obtain many variants of canopies with the adopted preliminary criteria, as well as to conduct genetic optimization, which helped to obtain the best results. For the best solutions in terms of geometrical forms, structural optimization was carried out due to the structures’ minimum masses. As a comparative criterion of structural effectiveness, a coefficient was used that specified the mass of the considered structure per square meter of the covered area. The proposed shaping method may constitute some guidelines for rational shaping of the steel bar structures with radially arranged modules, in which their effectiveness can be established already at the initial design stage. However, the best optimization results, that is, efficient and aesthetic canopies, can be ecological solutions to be used in practice.

Grid-type LED media façade with reflective walls for building-integrated photovoltaics with virtually no shading loss

Although anthropogenic climate change has demanded the development and use of building-integrated photovoltaics in zero energy building design, their poor aesthetic value has hindered their public acceptance. Accordingly, a grid-type LED display with reflective walls is herein proposed to bestow not only an aesthetic value to plain photovoltaic modules, but also an informative function as a media façade. Its lightweight, modular design enables it to be detachable and repairable. Upright flexible printed circuit boards embedded in the grid walls allow the use of wide copper electrodes and dual in-line package LEDs while casting virtually no shadows, leading to low resistive loss, excellent heat dissipation, and high luminance. The grid design exhibits a shading loss of only −3.67 %, which contributes to its superiority over conventional plane-type LED displays with a shading loss of −22.59 %. Reflective walls redirecting sunlight at solar incidence angles towards the photovoltaic modules lead to an average relative maximum power of 87.50 %, which is far higher than the 76.47 % achieved with opaque walls. The effective energy production simulations suggest that the grid-type LED displays can be run in a self-standing mode for up to 21.74 h per day. The presented grid-type LED display will contribute to the fast and wide adoption of building-integrated photovoltaics with increased public acceptance.

Research on BIPV in Office and Public Utility Buildings in Aesthetic and Utility Context

The idea of the article is to examine the perception of building-integrated photovoltaics (BIPV) by users of buildings in which BIPV has been applied. The study aims at determining the acceptance degree as well as problem areas related to the use of BIPV within façades in the aesthetic and utility context. The article includes survey research conducted among 232 employees working in six office and public buildings with BIPV in Poland. The buildings were selected so that the PV modules within their façades were visible both outside and inside the building. For this reason, two groups of buildings were chosen for the study: those with PV modules as external glazing and with an external PV shelves (three buildings each). The research results indicate differences in the perception of the aesthetic, semantic, and functional roles of BIPV depending on the aforementioned BIPV application method, the observation place (outside or inside the building), and employee characteristics, i.e., groups divided regarding such aspects as their age and time spent in the room with BIPV. The research novelty is in examining the influence of BIPV on users’ reactions in their workplace in terms of aesthetic and utility issues. The research includes post-occupancy evaluation method (POE), which is for the first time used in relation to BIPV in office and public utility buildings. The research can prove useful for investors and designers at the planning and design concept stage. The outcomes constitute a practical source of knowledge for BIPV manufacturers.

Technology Frontiers of Building-integrated Photovoltaics (BIPV): A Patent Co-citation Analysis

Abstract Recently, greater research attention has focused on the application of solar power generation technology in building construction to reduce building energy consumption and encourage increased sustainable development. An emerging solar power generation technology is in the use of Building-integrated Photovoltaics (BIPVs), where photovoltaic materials are used to replace conventional building materials. In order to map the development of BIPV technology over time and explore technology paths, this study retrieved a total of 4914 patents dated from 1972 to 2016 from the Derwent Innovations Index patent database. This study applies patent co-citation analysis to map the patent co-citation network in three periods based on Ucinet tool. Evolutional path and three key technology frontiers were identified using Social Network Analysis (SNA) and text clustering. The results of this study provide an informed reference for future researchers in understanding the historical development of BIPV, as an emerging and important solar power generation technology in the built environment. At the same time, big data of patents are analyzed using SNA and text clustering, which overcomes the limitation of previous methods of frontiers study that have depended on expert opinion or peer review.

Active surfaces selection method for building-integrated photovoltaics (BIPV) in renovation projects based on self-consumption and self-sufficiency

In light of the Paris Agreement's objectives and the related European and Swiss goals of decarbonising the built environment, the importance, relevance, and potential benefits of integrating Building-Integrated Photovoltaic (BIPV) within building renovation processes are acknowledged. Functioning both as envelope material and on-site electricity generator, BIPV can simultaneously reduce the use of fossil fuels and greenhouse gas emissions. Motivated by the current barriers and misconceptions that withhold a widespread integration of BIPV, particularly regarding financial implications and solar exposure levels that are believed to be unfavourable, this paper aims at bringing new knowledge and a rigorous and adaptable method to inform decision-making and promote the use of BIPV in urban renewal processes. Focusing on the architectural design, we here present a methodology to select active (BIPV) surfaces during the retrofitting process based on a trade-off between the self-consumption (SC) and self-sufficiency (SS) of a building. The approach consists in iteratively identifying surfaces that achieve a varying annual irradiation value (threshold). It also includes the evaluation of the effect of electricity storage systems. The methodology and the results of its application are presented through the comparison of two case studies in Neuchâtel (Switzerland). The outcomes of this new approach for addressing building renovation projects in the urban context can help architects, designers and engineers to better size the installation and the repartition of active surfaces in the renovated thermal envelope. Results show that it is important to take into account a larger range of irradiation levels to choose the active surfaces, especially in high-rise buildings with a greater proportion of façade than roof. In such cases, the irradiation threshold can vary between 600 and 800 kWh/m2·year depending on the strategy adopted in terms of Heating, Ventilation and Air-conditioning (HVAC) system improvement or storage system implementation. Such findings demonstrate the need for context-specific methods towards a proper evaluation and better valorisation of BIPV potential.

Solar and Shading Potential of Different Configurations of Building Integrated Photovoltaics Used as Shading Devices Considering Hot Climatic Conditions

This study investigates the use of building-integrated photovoltaics (BIPVs) as shading devices in hot climates, with reference to the conditions of Saudi Arabia. It used parametric numerical modelling to critically appraise the potential of eight design configurations in this regard, including vertical and horizontal shading devices with different inclination angles. The study assumed that the examined shading devices could be entirely horizontal or vertical on the three exposed facades, which is common practice in architecture. The study found that the examined configurations offered different solar and shading potentials. However, the case of horizontal BIPV shading devices with a 45° tilt angle received the highest amount of annual total insolation (104 kWh/m2) and offered effective window shading of 96% of the total window area on average in summer. The study concluded that, unlike the common recommendation of avoiding horizontal shading devices on eastern and western facades, it is possible in countries characterised with high solar altitudes such as Saudi Arabia to use them effectively to generate electricity and provide the required window shading.

The potential to exploit use of building-integrated photovoltaics in countries of the Gulf Cooperation Council

The use of renewable forms of energy is important throughout the world, not just in countries where there are concerns over the availability of fossil fuels. In order to develop and promote suitable energy policies for the future it is necessary to gain an understanding of stakeholder views in all countries, including those with substantial fossil fuel reserves. The volume of construction work in the Gulf Cooperation Council (GCC) countries has recently been at unprecedented levels, with a huge environmental impact from construction and also from potential future energy demands. The aim of this paper is to assess the potential to exploit use of a particular, but valuable, renewable energy option: building-integrated photovoltaics (BIPV) in those countries. Such exploitation could offset, at least in some part, the future environmental burdens. A large-scale survey, followed by a number of in-depth interviews, has been undertaken in order to examine the use of BIPV. Empirical research findings are presented, and then analysed in order to determine the current viability of a large-scale expansion of BIPV in the GCC region. The research indicates that the main factors hindering expansion are high costs and the negative public perception of BIPV in the countries concerned. Proposals are therefore provided to assist the development of suitable policies and the wider introduction of viable BIPV in the GCC markets.