Architectural Photovoltaic Application

Z. Haghighi

Research output: ThesisDissertation (TU Delft)

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Today, photovoltaic technology is one of the fastest-growing fields of technology and is becoming the lowest-cost option for electricity generation in the greatest part of the world. Based on IEA projection, the number of households relying on solar PV grows from today’s 25 million to more than 100 million by 2030. Based on this projection, we must use all surfaces on and around buildings of an entire city to absorb solar radiation and transform it into usable electricity (or useful heat). However, current attempts to harness these potentials within the built environment leaves much to be desired. It is readily apparent that the current roof-top installation approach is neither aesthetically appealing nor technically efficient and consequently not sustainable, long-term, and reliable. Back in the 1990s, the Integration approach was introduced to address these issues. However, the introduction of this solution has neither increased popularity nor helped with untapping the solar energy potentials within the built environment.
The fundamental problem addressed in this dissertation is the lack of appropriate guidance and well-structured knowledge about the approaches and considerations which should be deliberated in the design and decision-making process for deploying PV technology in architecture. The overarching goal of this research is to promote the use of PV technology in the built environment while being thoughtful of the symbiotic and functional relationship between the technology and the urban fabric. Specifically, it aims to support the decision-making process required for the adoption and development of photovoltaic products in the built environment.
This thesis builds upon the interrelations between the concept of Integration, design decisions, and technological decisions. As the starting point, we looked into ‘integration’ as an alternative approach to the existing addition or attachment of PV into buildings. To do so, we explored given definitions and requirements outlined for the concept of Integration within the context of the application of PV in building architecture. In existing literature, integration is described as the solution for wider adoption and acceptability of PV in the built environment and defined as situation where PV module replaces a building material in a building. However, our findings show that integration does not presume photovoltaic products to be used as part of the construction material and serve a secondary or tertiary function. Furthermore, it highlights under the definition of Integration, the PV system can still be part of the architecture and remain a building service and perform a singular function as a renewable energy generator.
In the next step, we looked into how architects have used PV technologies in buildings. We shortlisted 30 projects and categorised them based on those design decisions that made them different from one another. We highlighted that these projects could be categorised based on decisions made on (i) visibility of PV system in the building architecture, (ii) mounting strategy and structural connection of PV panels and building, (iii) the customisation level of PV module, (iv) the building fabric used, and (v) the role of PV in the building system.
Subsequently, 30 architects were interviewed to study their experiences and perceptions about the architectural application of photovoltaic. In this study, we approached two groups of architects: one with experience of using PV technologies and the other with no relevant experience. Based on the input received, we witnessed three types of motivations for using PV technologies in architecture projects: the first type was related to external incentives that drive the project (e.g., NZEB), the second type was rooted in the architect’s interest in environmental-friendly and climate-responsive technologies in buildings, and the final one is a communicative gesture in which PV technologies was used as a symbol of sustainability mandated by the project owner. The findings also shed light on the differences in opinions between architects who had already applied PV technology and those who had not. Unlike those with experience working with PV technology in their previous projects, who believed that working with this technology is not complex and problematic, the group with no experience believed that working with PV technology is challenging. Furthermore, a common opinion between the two groups was the need for more versatility in colour, transparency, size, and reflectivity of module products.
In the following step, we looked into the existing PV technologies and explored their its various features and potential in architectural application. The findings highlight that the first-generation technologies (c-Si) are the most advanced and can perform better for building applications. However, the physical flexibility of this technology for customisation on the cell level remains limited. In the second-generation technologies, higher temperature tolerance is an advantage for them to be compatible in situations where double-sided ventilation is not possible. Even though most of the second-generation technologies are already lightweight and flexible, and although it they have some level of transparency in contrast to the first generation, their automated production lines make customisation of size and shape fairly difficult. The third-generation technologies received more attention because they offer lower production costs, reduced environmental impact, and a relatively higher efficiency compared to the first and second generations. This makes them an interesting option for architectural application, even though their limited service life expectancy remains an important disadvantage. Aside from the criteria mentioned for comparing these alternatives, many other factors are involved in finding the most suitable PV technology for a certain application. The architects interviewed highlighted these criteria. So, we looked into advanced decision-making methods to see if such methods can be applied in the selection process of PV technology. Through the development of a pilot tool on multi-criteria decision making method, analytic hierarchy process, and test within a concept development project, we concluded that such a method can be very helpful in finding the most suitable technology for a certain application.
In the final stage, we worked on development of new concepts for the application of PV technology in buildings as based on several reports reviewed and on results of interviews, it became apparent that existing PV products cannot fulfil current market demands and consequently the sustainability targets. We then examined the R&D processes of these projects, which showed that despite the differences in scope, objective, and nature of the concepts, several similarities could be articulated into a generalised concept development process. According to this analysis, the R&D process before the commercialisation phase can be divided into 7 steps, namely (i) scoping and definition (ii) exploration (iii) concept development (iv) proof of concept (v) optimisation (vi) application design development (vii) prototyping.

Overall, the findings of this research can be summarized in three recommendations: first, integration in this context as perceived and defined in the standards and manuals cannot be seen as a comprehensive approach to include all the architectural styles and approaches to use PV technologies in buildings. Therefore, rethinking its definition and requirements is essential. Secondly, suppose we want PV technology to become a default building service, we need to leave it to architects to accommodate it within the design concept as they wish, and the PV industry should not try to impose this technology on architecture. And lastly, we need to develop a new discipline around the design and engineering of energy-producing buildings. We need to train and equip future practitioners with insight, know-hows, and tools to use the ultimate solar energy potentials to produce energy, store, and utilize the generated energy on-site.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Delft University of Technology
  • van den Dobbelsteen, A.A.J.F., Supervisor
  • Klein, T., Supervisor
  • Konstantinou, T., Advisor
Award date7 Nov 2022
Electronic ISBNs978-94-6366-612-1
Publication statusPublished - 2022


  • BIPV
  • architecture
  • Solar energy
  • integration
  • Renewable energy
  • Green Building
  • Sustainable construction
  • Sustainability
  • Zero energy housing
  • Photovoltaic (PV)

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