Project | Active Thinking——Building Integrated Photovoltaic Design for the Permanent Venue of the World Top Scientists Forum

 

 

01.

Project Background

Building Integrated Photovoltaics

 

Building Integrated Photovoltaics (BIPV) is a technology that integrates solar photovoltaic power generation systems directly into the building envelope. Specifically, it installs photovoltaic modules on the roof, walls, and sunshades of the building, not only providing electricity but also serving as a functional part of the building structure, replacing some traditional building materials such as tiles and glass curtain walls.

/ Photovoltaic Roof /

/ Photovoltaic Facade /

 

/ Photovoltaic Carport /

BIPV technology has three main characteristics: First, it is energy-efficient and environmentally friendly. BIPV can effectively utilize solar energy resources, reduce reliance on traditional energy, and lower the building's energy consumption and carbon emissions; second, it is aesthetically pleasing and practical. Photovoltaic modules, as part of the building materials, not only provide electricity but also integrate with the building's appearance, enhancing its aesthetics; third, it offers economic benefits. Most of the electricity generated by the BIPV system is consumed by the power-consuming equipment within the building, and the surplus electricity can be injected into the grid, achieving self-sufficiency in energy and grid-connected power generation.

General Code for Building Energy Efficiency and Renewable Energy Utilization

Implementation Opinions on Promoting the Application of Renewable Energy in Newly Constructed Buildings in This City

 

In order to actively promote the rapid development of the building-integrated photovoltaic application field, China has introduced a series of policies and regulations, such as the "General Code for Building Energy Efficiency and Renewable Energy Utilization" issued by the Ministry of Housing and Urban-Rural Development in October 2021. The Shanghai Municipal Government requires in the "Implementation Opinions on Promoting the Application of Renewable Energy in Newly Constructed Buildings in This City" that "newly constructed public buildings, residential buildings, and public utility plants whose construction drawings are submitted for review after March 1, 2023, shall comply with these opinions (see table below)." These policies aim to incentivize and support the integration and application of photovoltaic technology in buildings to promote green and sustainable energy utilization.

Table of Area Ratio for Rooftop Solar Photovoltaic Installation

 

Given the policy-driven promotion requirements for photovoltaic applications, and the positive impact of photovoltaics on economic development and environmental protection, building-integrated photovoltaics has become an inevitable trend in building development. Although there are still some challenges in photovoltaic applications in building technology, for architects, photovoltaics is also a new form of design expression and means, and architects should take a proactive attitude and actively adapt to this transformation. This article takes the World Top Scientists Forum permanent venue project as an example to comprehensively introduce our exploration in the application of building-integrated photovoltaics.

 

 

02.

Project Overview

Building Integrated Photovoltaics

 

The World Top Scientists Forum permanent venue project is the first project in the Lingang World Top Scientists Community. Positioned as a "world-class major frontier scientific source in the new era," it serves as the permanent venue for the World Top Scientists Forum. The total construction area of the project is 223,827 square meters, with the main functions being a top science forum conference center complex and supporting theaters, libraries, science exhibition halls, and hotels. The entire building unfolds towards the city like double wings, with undulating photovoltaic roofs that seamlessly integrate with the building, expressing the beautiful vision of "spreading the wings of the future and gathering the light of technology."

/ Front Semi-Bird's-Eye View /

 

Wings of Science, Connecting the City

The entire building is arranged in north-south zones, with the conference center to the north and the hotel and apartment-style hotel to the south. The design integrates and streamlines the city's spatial relationships, emphasizing the combination of natural and humanistic environments, and differs from the previous cold and negative stereotypes of convention centers. It hopes to create a vibrant venue.

/ Functional Analysis Diagram /

 

The design introduces vehicular access to the second-floor platform, opens up the ground floor space to introduce pedestrian traffic, and creates an organic spatial sequence combined with rich functional spaces, linking to the park on the south side; the stepped terraces of the hotel's annex building continue the wing design concept, forming a reciprocal landscape dialogue with the planned park on the south side.

/ Morphology Generation Analysis Diagram /

 

Green and Low Carbon, Throughout

The dual-carbon goal is China's commitment to the international community, and "Science, for the common destiny of mankind" is the eternal theme of the World Top Scientists Forum. From the beginning of the design process, the design team considered the building's energy consumption control, such as the building's shape coefficient, window-wall ratio calculation, external shading of different orientations, etc.

/ Green Building Analysis Diagram /

 

Through the calculation and analysis of the design scheme's comfort, energy consumption, and lighting, a harmonious and unified building facade with constantly changing orientations has been formed. By comprehensively using climate-responsive design, high-performance building envelopes, efficient electromechanical systems, and integrated photovoltaic design, the building has become Shanghai's first public building project to pass the ultra-low energy consumption scheme review. Among them, the integrated photovoltaic design is one of the highlights of this project's achievement of ultra-low energy consumption buildings.

/ Elevation /

/ Photovoltaic Roof Bird's-Eye View /

 

 

03.

Architects' Knowledge Reserve on Building Integrated Photovoltaics

Building Integrated Photovoltaics

 

Before undertaking photovoltaic design, architects need to have a certain understanding of building-integrated photovoltaics, including the impact of solar radiation on photovoltaic panels and the possible application methods of BIPV in buildings.

 

Solar Radiation and Photovoltaic Panel Installation

Given the characteristics of solar radiation, the optimal tilt angle during photovoltaic panel installation is crucial. The optimal tilt angle can improve the energy output efficiency of the photovoltaic panels, thereby increasing the efficiency of the solar power generation system. For large-scale photovoltaic panel deployment, determining the optimized installation angle is crucial.

/ Schematic Diagram (Source: Internet) /

 

The calculation of photovoltaic panel laying density is also a meticulous and complex task. It not only needs to consider the angle optimization of the photovoltaic panels but also needs to take into account the reduction of shading effects to maximize light reception. In implementing photovoltaic projects in urban environments, it is impossible to enjoy unlimited spatial intervals like in desert areas, so the ratio of light intensity to the area that can be laid must be balanced.

 

Through comprehensive analysis, the aim is to maximize system efficiency, and this process often involves economic considerations, namely a comparative analysis of investment costs and power generation returns. This is the basis for deciding the overall tiling strategy. Based on these principles, designers can innovatively derive a variety of design schemes to create both efficient and aesthetically pleasing building photovoltaics.

 

BIPV Applications in Buildings

Generally, there are two main ways to apply photovoltaic arrays in buildings:

The combination of photovoltaics and buildingsThis is the most common method, mainly integrating photovoltaic arrays with building roofs, walls, etc., such as photovoltaic roofs and photovoltaic curtain walls. This method does not occupy space outside the building, and is the most widely used and optimal installation method for photovoltaic power generation systems in cities^[1]For example, the metal roof of the exhibition hall on the north side of the project has photovoltaic panels installed on brackets.

Integration of Photovoltaics and BuildingsThis is an advanced form of BIPV. Photovoltaic components must not only meet the basic functional requirements of photovoltaic power generation, but also the functions of building components, such as waterproofing, heat insulation, and load-bearing^[2]The light-transmitting atrium roof of the hotel annex on the south side of the project uses this integrated method, with photovoltaic panels serving as the glass top of the atrium, acting as both photovoltaic and exterior curtain wall.

Photovoltaic Design for the Metal Roof of the North Exhibition Hall

Photovoltaic Design for the South Hotel Annex

 

 

04.

Specific Applications of Photovoltaic Integration in the Project

Building Integrated Photovoltaics

 

The Dingke project, from its initial design without photovoltaics to the final completion with integrated building photovoltaics, has undergone multiple rounds of design optimization and iteration. Ultimately, the project's photovoltaics are mainly applied to the building roof and atrium skylights. Throughout the design process, the architects collaborated closely with green building and BIM professionals, integrating photovoltaics as a design concept, fully considering both their efficiency and compatibility with the architectural design.

 

Combination of Photovoltaics and Roofs

The unique structural design of the project's roof stems from its wing-like architectural form. This specific design directly determines the layout of the photovoltaic panels. It should be noted that during the architectural design process, the architectural form may inevitably be adjusted, and the layout strategy of the photovoltaic system must be adjusted accordingly. This highlights the importance of architects comprehensively considering the integration of architectural form and photovoltaic systems, ensuring harmony between the two.

/ Design Renderings /

 

The undulating photovoltaic form of the conference center roof needs to be optimized under the guidance of the design concept, combined with BIM design. To achieve the architect's design concept of soaring wings, using parametric technology, the design team simulated and compared different roof undulations, including linear roofs and hyperbolic curved roofs.

Linear Roof

Hyperbolic Roof

 

Combining the sun's angle of incidence and the needs of the building's shape, the design integrates the staggered roof of the theater, taking into account the air circulation of the roof equipment. Through parametric design simulation of the optimal light angle, maximizing power generation, and considering occlusion factors, monocrystalline silicon thin-film components are selected to avoid the formation of light spots that damage the components.

/ Rhino + Grasshopper Assisted Integrated Design of Photovoltaic Building Structure (Drawing: Liu Wen) /

 

Adhering to the design concept of wings, the photovoltaic components adopt a modular layout strategy. Each photovoltaic panel is installed at a 15° inclination angle, creating a well-ordered, layered, and dynamically aesthetic wing-like array structure.

/ Completed Real Scene Image /

 

The gaps between the unit panels provide a good ventilation environment for the roof equipment units. This modular photovoltaic design also significantly saves costs. The main steel beam structure of the photovoltaic bracket under the irregular shape was completed using Rhino's single-line positioning and Revit Dynamo parametric solid model conversion, achieving efficient and batch interaction of data formats between multiple heterogeneous models.

/ Summary of Integrated Design Process of Photovoltaic Building Structure (Drawing: Liu Wen) /

 

Photovoltaic Selection

In the process of material selection, we faced various considerations. First, the color of the material. The initial design used light-colored materials, however, the photovoltaic conversion efficiency of this design was significantly lower, and we were unwilling to sacrifice the functionality of the photovoltaic system simply for aesthetics. Subsequently, we comprehensively evaluated several dark-colored materials, including dark gray, blue, and purplish-red. To achieve a balance between function and aesthetics, we ultimately chose dark gray materials.

Light-Colored Photovoltaic Design

Dark Gray Photovoltaic Design

 

In this project, cadmium telluride thin-film components (85W per piece) were used on the roof of the conference center, with modules measuring 1.2*3.6 meters, totaling 2690. Each module has 6 cadmium telluride thin-film components connected in parallel, for a total of 16140 components, with a total installed capacity of 2000 kW.

/ Photovoltaic Component Installation Diagram /

 

Another aspect to mention in architectural photovoltaic design is the design of the edge of the photovoltaic panels. The roof is not a regular square; the edge portions of the parametrically generated photovoltaic panels are not complete rectangles, so other materials are needed to simulate the effect of photovoltaic panels to achieve a uniform overall aesthetic. Initially, we tried using the glass material from the photovoltaic panels to create "fake photovoltaics," but later found the cost to be excessive, so it was not used. Later, we used aluminum panels; after adjusting the color and luster, the difference from the photovoltaic panels is barely noticeable.

/ "Fake Photovoltaics" in Appearance Design /

 

In architectural design, we further considered the balance between architectural aesthetics and energy efficiency. After deciding to use dark gray photovoltaic panels, we immediately made corresponding adjustments to the architectural design, including the color of the facade glass and the overall facade color scheme. During this adjustment, we made extensive revisions to ensure that the building's exterior and the color of the photovoltaic panels coordinate, resulting in the current building effect. This demonstrates the close association and mutual compromise between function and aesthetics throughout the design process.

/ Coordination and Unity of Photovoltaic Design and Facade Design /

 

Combination of Photovoltaics and Atrium Skylights

The hotel annex uses a slanted photovoltaic glass roof design incorporating the skylight shape, improving natural lighting and ventilation in the deep annex. The angle between the roof and the horizontal plane balances power generation efficiency and the indoor spatial feel. Through simulated calculations and comparisons of various numerical light transmittance values, a 40% light transmittance photovoltaic glass was ultimately used, ensuring a certain power generation capacity while meeting indoor lighting needs. Solar roof panels were customized based on the architectural design plan, with a usable roof area of approximately 2100 square meters and an installed capacity of approximately 230 kW. The skylight glass uses triple-glazed, double-cavity tempered ultra-white glass, with battery chips set in the interlayer of the outer double glazing, effectively absorbing solar radiation heat^[3]In addition, it provides heat insulation, reducing the air conditioning load. The sloped photovoltaic glass roof design achieves the best balance between indoor transparency and shading needs, creating a comfortable indoor space.

/ Hotel Indoor Photovoltaic Glass Top /

 

The Role of BIM Technology in the Project

BIM technology played an important role in achieving the photovoltaic integration of this project. We use parameterization as a means to guide the implementation of non-linear design results, realizing a visualized construction process guided by "physical objects".

The photovoltaic brackets and the main steel structure are deepened and constructed synchronously, guiding the construction of the roof structure system with the concept of integrated construction of steel structure units.

The roof secondary structure layout scheme is fully considered, and the construction relationship between the roof structure and the roof equipment is fully coordinated.

Deepening of the prefabricated installation scheme for photovoltaic panel secondary structure brackets, reducing the amount of on-site welding work.

/ Integrated Implementation of Multi-professional Photovoltaic Roof System (Drawing: Liu Wen) /

 

Multi-professional Collaboration of Photovoltaic Roofs——Apart from the topmost photovoltaic roof, the large roof of the conference center is very complex, involving multiple professions and multi-dimensional special projects, such as photovoltaic columns and the main structure, roof-exit wells and pipelines, drainage ditches, etc. When multiple variables are adjusted together, it is difficult to achieve rapid coordination. However, BIM 3D technology can clearly and completely reflect the spatial relationship between these components, even the contradictory relationship in construction methods, in a very short time. Finally, the project conducted multiple rounds of checks and design optimization through the 3D model.^[4]，achieving the integrated implementation of the photovoltaic roof.

/ BIM Structural Model under Roof Photovoltaics (Drawing: Liu Wen) /

 

Model Quality Control——The facade model has been accompanying the design process, updating the model prior to the drawings. The model controls the quality of the facade drawings, especially the non-linear folded surface modeling part of the hotel annex building. By outputting the developed facade through the model, it is convenient for the curtain wall profession to carry out the layout and deepening of each panel.

BIM Model

Development Drawing

Curtain Wall Deepening Drawing

/ Positive Drawing Based on BIM Model (Drawing: Liu Wen) /

 

Therefore, the professional deepening design and deepening drawing output based on the BIM model has improved the quality of the drawings, solved the difficulties in construction, optimized various construction technical schemes, and helped the high-efficiency and high-quality advancement of the permanent site project of the top scientists forum.

/ Roof Photovoltaics Shining under the Setting Sun /

 

 

05.

Conclusion

Building Integrated Photovoltaics

 

The successful application of photovoltaic integration technology in the permanent site project of the World Top Scientists Forum demonstrates its advantages in terms of aesthetics, structural safety, environmental protection, and economic benefits. As an international exchange platform, the BIPV technology adopted by this project will undoubtedly attract global attention and become a model for learning and reference. This successful case not only sets an example for the development of building-integrated photovoltaic technology in China, but also promotes exchanges and cooperation in the fields of green building and renewable energy utilization at home and abroad.

From the perspective of architects, photovoltaic integrated design is oriented towards overall design, using photovoltaics as building elements, aiming to explore its rich expressive power and application potential. This includes adopting appropriate design methods according to different spatial effects, and comprehensive consideration of the integration position and material of photovoltaic structures to achieve maximum power generation. In actual projects, architects constantly explore, transforming research results into design methodologies to provide guidance for photovoltaic integration applications. It is hoped that more architects will enhance their acceptance of photovoltaic building integration, actively innovate, and better integrate it into building design.

With the continuous progress of new energy technologies and the increasing demand for energy saving, emission reduction, and green environmental protection in cities, building-integrated photovoltaic technology will be more widely applied. It is expected that its market size will gradually expand, becoming a key component of the digitalization and intelligence of modern buildings, committed to creating a more beautiful, comfortable, and environmentally friendly building environment.