Jan. 13, 2025
On March 7, , the U.S. Department of Energy (DOE) Solar Energy Technologies Office (SETO) and Building Technologies Office (BTO) released a Request for Information (RFI) on technical and commercial challenges and opportunities for building-integrated and built-environment-integrated photovoltaic systems (BIPV). Both SETO and BTO have supported research, development, demonstration, and commercialization (RDD&C) efforts on BIPV via a variety of programs. The purpose of this RFI was to solicit feedback from various stakeholders, such as industry, research laboratories, academia, government agencies, regulators, and other experts, on issues related to BIPV technologies and markets. Such input would help identify and quantify remaining barriers and explore key opportunities to inform future strategy program development in this area.
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The BIPV RFI received 37 responses from organizations representing BIPV stakeholders including product manufacturers, trade associations, utilities, architecture & engineering companies, local government, academia, research organizations, national laboratories, consultants, and individuals.
Respondents addressed questions in five different categories, spanning the current state of the industry, product requirements, key barriers, RDD&C needs and opportunities, and stakeholder engagement. Respondents framed their responses based on specific questions in each category, though some of them outlined their answers differently around themes of interest spanning various categories and providing some more general comments. This summary document is organized around the categories identified in the RFI and the individual questions. See the full questions in the RFI.
Products:
Customer segments:
Marketing:
Product sourcing:
PV cell technologies:
Based on responses received, a variety of product segments were identified as being pursued in the United States. The list includes:
In terms of markets served, most of the respondents indicated a focus on residential or commercial buildings. This was an almost equal split, with slightly more responses giving preference to commercial buildings and the majority pursuing both markets. It was noted by some respondents that their strategy is to initially target commercial buildings and then move to the residential market, as they see more difficulties for the residential segment due to less willingness of owners to pay and lack-of-standardization concerns for BIPV products. Some special segments of the commercial building market, like government buildings, educational facilities, hospitals, manufactured houses, and agricultural facilities were also identified by the respondents as being of interest and of their primary focus. The following segments were specifically mentioned:
In terms of new buildings or retrofits, the vast majority of respondents mentioned being involved in both sectors with few of them only focusing on new buildings.
A variety of information was provided with respect to the alignment of commercialized BIPV products and market segments. Some responses viewed the topic from the customer market segment perspective and others from the side of the BIPV product and application. It was also noted that, assuming availability of various BIPV products, the type of BIPV should be dictated by the aspect ratio of the building. Larger roof areas (like in warehouses) would naturally be a better fit for rooftop solar, while taller, skinnier buildings (like high-rise office or residential buildings) would be better fit for glazing or façade products.
Overall, most of the respondents considered the extended commercial building market to be best aligned with commercialized BIPV products. This market includes high-end commercial office and retail buildings (which have fewer cost constraints and can use the technology as marketing point), educational facilities, such as schools, colleges, and universities (which consider educational and research benefits of incorporating new technologies, especially in the science and technology sectors), hospitals, hospitality buildings, and warehouse facilities (which consider weight issues and reduced need for puncture of membrane roofs). New construction commercial projects seem to have the most potential.
The residential building market seems to be interested in the appeal of aesthetics of BIPV compared to tradition rooftop PV products. Development of more aesthetically pleasing products would be the best strategy for alignment with this market, though cost is also a significant factor. Multi-family homes and high-rise buildings seem to be the most promising segments. New constructions seem to be perceived as better aligned compared to retrofits.
In terms of products, roofing products are perceived to be best aligned with the market, both for commercial and residential applications. Power generating windows and other glass products are secondary, with more appeal on in commercial applications. However, responses indicate that most of the existing products need further development as they might not be fully aligned with the market needs. Another product category identified is shading elements, awnings, and in particular carports and parking shade covers.
Respondents also provided some insights about differences between the U.S. markets and markets in Europe or elsewhere in the world. It was noted that in the United States, residential and commercial roofs for new constructions align well with existing BIPV products in the space, but elsewhere in the world, many more commercial products are available for building façades for high-rise buildings, offices, government buildings, educational facilities, sports arenas, airports, and public areas. In Europe, there have been large commercial projects integrating BIPV glass as well as several small-scale commercial projects integrating BIPV walls and façades.
A variety of information was provided on the market opportunities for BIPV products. Like in the previous question, some responses viewed the topic from the customer market segment perspective and others from the side of the BIPV product and application.
Respondents perceived the largest market opportunities for BIPV to be in the commercial sector; however, residential applications were also considered to present great opportunities. In the commercial segment, corporate offices, retail buildings, storefronts, public buildings, government buildings, educational facilities, hospitals, and light industrial facilities were specifically identified as promising. Opportunities for older buildings with large power needs at places where the grid infrastructure is older were mentioned as well as applications that combine conventional rooftop solar with additional BIPV elements. For the residential sector, multi-family housing and low- and mid-rise buildings with a high ratio of wall-window to roof area were considered the largest opportunities. Incorporation of BIPV into manufactured housing and modular construction production lines was also identified as a promising opportunity. In terms of location, it was mentioned that the state of California would provide a large market opportunity because of the state requirements with respect to climate change and clean energy.
When viewing opportunities from the BIPV product perspective, three product categories were identified as being the most promising in the market:
Regarding PV glass and power generating windows, respondents explicitly mentioned the stacking benefits of glass capturing infra-red light and thus also reducing heat transferred into the building.
Respondents also noted that a comprehensive market characterization and assessment is necessary, as the market opportunity will be eventually defined by the adoption and market-pull for these products, not by the theoretical availability of BIPV products that could replace a particular building element. Another view presented was the perspective of using the energy generated to offset the cost of the building element that is required by the building.
Respondents approached this topic from various different angles and provided different types of information related to marketing strategies, manufacturing locations, industry composition, and PV cell technologies mostly used by BIPV products. Some respondents noted that marketing efforts are very limited and are done on a project-per-project basis, and this is considered a contributing factor to the limited uptake of BIPV technologies.
In cases where developers or designers are more familiar with BIPV products, sourcing would follow the pattern of an interested architect or building developer reaching out to a BIPV product vendor. BIPV products are often marketed as elements of total-building approaches to achieve high LEED or similar scores. They are offered by the supplier to real-estate developers and architects with a promise of return on investment based on the electrical cost offset from the generated electricity as well as on applicable local incentives. Non-electrical benefits, such as acoustics, thermal, safety glazing, or UV light blocking, are also listed but often not included as part of the economic consideration. The dual-use and aesthetic aspects of BIPV compared to traditional PV products is another marketing point typically used.
There is a growing interest in U.S. manufacturing, as evidenced by the number of foreign-owned companies that have opened or are opening plants in the U.S., in addition to U.S.-owned companies that already have manufacturing facilities. The U.S. has established itself as a leader in the manufacturing of rooftop-integrated solar, but other companies could be incentivized to develop manufacturing capabilities that include PV integrated into windows, building façades, and other substrates. In addition, a growing number of innovative BIPV ideas have emerged across smaller companies and startups in the United States. Respondents, however, have noted that currently there are insufficient economic incentives for the development of domestic manufacturing of BIPV products and their respective supply chains in the United States. Tax incentives or grants to support BIPV manufacturers who wish to manufacture in the U.S. and for businesses to procure these products could be a driver for adoption.
In general, it is ideal to manufacture components as close to the market as possible as this reduces costs and speeds up development. The impact to the cost of the final product could be lowered, if the bulk of the raw materials and final assembly are completed domestically or regionally (especially if tariffs are considered). It is customary for the building industry to use local manufacturing and source materials locally, so it would be meaningful for BIPV to follow the same paradigm. Many building materials used in such products are large and heavy enough that makes sense to produce domestically and even regionally throughout the country to reduce transportation costs and logistics, which could account for 10-15% of the cost, in some cases. Other benefits include manufacturing to order, reduced inventories, on time delivery, quick deployment within the region, quality control, and the ability to better meet various sustainability requirements, while also ensuring supply chain security. It was also identified that cybersecurity of BIPV systems, as it pertains to their electronics and control hardware and software, provides another argument for domestic production.
The roofing industry lends itself to domestic manufacturing, with shipping costs being a major reason. The main challenge to the development of BIPV roofing is sourcing of materials and manufacturing of the non-industry standard-size solar roof tile. There currently exists very limited domestic capability for this need. The specific glass used in PV modules is made only in Asia today and is difficult and costly to source. Manufacturing equipment and facilities do not currently exist for specific solar tile sizes, and this not only increases cost but also lengthens development time. This creates needs and opportunities for developing domestic manufacturing capabilities.
Glass is also produced close to the consumptionsite due to high transportation costs because of the brittleness and weight of the product. Most windows are manufactured domestically, and insulated glass units (IGUs) follow this same pattern. IGUs are primarily ordered and manufactured regionally/domestically, due to custom specifications, sizes, and lead times. By extension, it is reasonable to conclude that solar windows and other glazing-based PV products are well-suited for domestic manufacturing. Solar windows are unlikely to be exported globally from a single manufacturing site as this could be cost prohibitive. If the integrated photovoltaic function does not involve fabricating semi-transparent solar cells over the entire window area, but rather only employ commercial solar cells (e.g. crystalline Si based) outside the window viewing area and thin-film coating techniques, then it is very feasible to integrate the photovoltaic window manufacturing/assembly alongside the existing window manufacturing facilities. It could also seamlessly integrate into the existing IGU supply chain (glass fabricators can apply PV coatings), which further ensures domestic manufacturing and that the revenue uplift from the value-added BIPV window product is captured domestically as well. Semitransparent OPV power generating windows also have a significant opportunity for domestic manufacturing.
Respondents also identified a few additional, more specialized opportunities for domestic manufacturing, such as cadmium telluride (CdTe) as the semiconductor for PV modules, pre-engineering and assembly of unitized curtainwall panels, manufactured homes incorporating BIPV, and emerging products that rely on advanced manufacturing like quantum dots.
Respondents described a variety of advantages that regional BIPV product manufacturing would provide. Such benefits pertain to:
It was also noted that this topic should be more thoroughly addressed within an economic framework that will consider factors like the costs of building and operating regional manufacturing facilities, the cost and availability of raw materials at a distributed scale, projected long-term product demand per region, the ability of a smaller manufacturing facility to adapt to new products and production equipment, and how the latter stacks up against projected savings in transportation and breakage costs.
Respondents pointed out that a variety of BIPV products exist on the market, but many of them are still not mature enough to be considered truly competitive, pointing out a few reasons for this assessment. Currently there exists a tradeoff between the cost of BIPV and the aesthetics of a system. The cost is a function of the difficulty in sourcing components as well as the complexity of installing the system. Installation complexity of the most aesthetically pleasing systems appears to be high. Products have not been successful so far either because of aesthetics improvements not being substantial to justify the higher cost or because of limited support services provided to the installers to sell and design these products. Products that have excellent aesthetics have often been too expensive for adoption beyond early adopters. In addition, BIPV systems do not seem to payback within an assumed 20-year lifespan of the product, based on energy generation. This is attributed to insufficient solar to electric power conversion efficiency combined with suboptimal solar orientation, and it makes the business case for BIPV weaker. It was also identified that the BIPV market is currently unstable as it is largely supported by a few specialty manufacturers who could abruptly withdraw, causing an entire market segment to collapse.
Nevertheless, respondents identified specific BIPV product categories and commercial products that in their opinion are the current most competitive ones on the market:
In terms of competitive PV cell technologies used in BIPV products, respondents indicated that monocrystalline Si panels (similar to those commonly used for BAPV) are the most competitive due to cost, efficiency, and reliability. Silicon products have advanced more than other thin-film products for BIPV, but BIPV provides unique opportunities for thin film. Currently, a-Si is the dominant player in the market, because it is a mature, scalable, and relatively low-cost technology. Organic PV (OPV) cell technologies were also mentioned, mainly for windows and other glass applications. Respondents also provided information on this topic in the &#;Marketing and sourcing of current BIPV products&#; section of this report under the &#;State of the industry and key domestic markets&#; category.
Respondents also identified specific companies and products in the BIPV space that they consider to be the most competitive in the current market. The companies and products referenced were:
Respondents overall identified that a number of factors such as performance, cost, lifetime, reliability, code compliance, supply chain integration, design process integration, aesthetics, and installation process are all important factors in the requirements for the BIPV industry and overall market. Responses were provided considering BIPV products in general and specific product categories.
The following overarching requirements, spanning all BIPV product categories were identified:
Identified (ideal) requirements for BIPV roofing products include:
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Identified requirements for glass products (windows, insulated gas units, glazing) relate to:
The majority of the respondents identified standardization and code compliance as the major challenge that BIPV are facing with respect to performance requirements of building materials. More specifically, responses revolved around the following issues:
Respondents indicated that the alignment between performance requirement and BIPV applications might depend on the product and the product design in a particular category as well as the specific requirements for the category. However, there are some common themes that emerged from the responses.
Respondents identified a number of factors and perceptions that are weakening the value proposition for BIPV and are thus limiting the uptake and faster deployment of such technologies. These factors are grouped in the following areas and summarized below:
Costs are a significant barrier, particularly in the lack of tax credits or other incentives. The resulting high cost and long payback period make it challenging to cost-justify BIPV into new or existing buildings and structures.
The information received under this question was rather limited. Respondents identified a few factors that are limiting collaboration and partnerships on BIPV technologies between members of the solar and the building industries. These factors are grouped in the following areas and summarized below:
The way to increase the collaboration/partnering on BIPV technology needs to educate the solar and building industries about BIPV products and then provide incentives for their use through programs or building code accommodations. Once customers understand the value of BIPV, a market will be created, and collaboration will follow. Academic research can define the benefits of BIPV to the solar and building industries. By providing local governments grants or additional funding, the early projects can be launched and highlighted to encourage future collaboration.
Some work has already been performed in modeling of the production cost, installed system cost, and energy yields for BIPV technologies and systems in conjunction with partners and experts across the supply chain, including NREL, and the DOE. The most important next step to improve these models is to demonstrate and test them in real world production. This would also result in obtaining realistic field data also addressing the issue of unavailability of such data, which was identified as an important limiting factor of the current BIPV modeling. Nevertheless, it appears that in practice there are still information gaps, issues to be addressed, and improvements to be made and respondents have identified the following limitations in regard to the current modeling of the production cost, installed system cost, and energy yields for BIPV technologies and systems:
Most of the current PV modeling software is designed for modeling of ground-mounted or rooftop solar systems applied to buildings. Such PV performance models do not accurately capture the unique aspects of the BIPV package and, therefore, do not give accurate information for performance or cost when used in conjunction with BIPV applications. These limitations could be overcome to some extent by adding new models within existing production modeling software, instead of developing custom production software for BIPV. However, it was also pointed out that gaps in current modeling tools for BIPV are also largely due to the fact that most BIPV tools are either standalone software or part of distribution grid simulation software. It would be more effective for BIPV models to be an integrated part of building simulation software to leverage the existing capacity and resources in building energy modeling tools and study the impact and control of BIPV together with other building energy assets.
Taking it even further, more complex, physics-based models, which run thermodynamic simulations to estimate the energy consumption and capture the physics-based heat transfer relationship between heating, cooling, temperature and energy consumption and generation could be used, especially for more advanced research studies. But such models are computationally expensive and require very detailed input data, which might typically be unavailable for most buildings.
Overall, it appears that there is need for both high- and low-fidelity simulation models. High-fidelity simulations, coupled with field work or experiments, could support research purposes, and should be used to validate the coarser tools developed for engineers/architects. Ideally, an integrated modeling system would be developed that spans length scales and unites PV cell/module properties up to building performance and large-scale deployments with many buildings or cities.
Respondents identified several limitations that exist in current evaluations of BIPV systems compared to traditional building applications for energy performance, electricity generation, and carbon emission reduction. Such limitations are grouped in the following categories:
Another key limitation with respect to data is lack of standardized data sources of city-scale building data that are needed for evaluating BIPV systems. Those data sources should include various levels of building characteristic such as basic properties (e.g. use type, year built, change history, building permits, etc.), geometry (e.g. footprint, height, number of stories, total area, etc.), location and climate, energy systems (e.g. HVAC, lighting, internal loads, service hot water etc.), building envelope information (e.g. construction type, insulation for walls and roofs, window properties, etc.), and actual energy consumption data and utility bills. Besides the data for individual buildings, several other datasets are required for BIPV system evaluation, including weather data, local building energy codes and standards, utility rates, and cost data of building technologies.
Respondents have noted that very little research or development has been performed on BIPV technologies in the U.S. which could address the numerous challenges identified. Therefore, several areas for research, development, and demonstration have been identified:
Respondent input was limited but overall, the following issues were identified:
Regulatory compliance was one of the key barriers that respondents have identified for BIPV deployment pertaining to both the product certification as well as permitting requirements. This topic was also covered by responses to the third category about key barriers and perceptions. The following issue were identified by the respondents:
BIPV technologies requiring both construction and solar technologies code compliance and, therefore, face greater barriers than solar alone. The multiple testing protocols needed for a base product and potential repeated testing for customized products add time and expense in getting the required certifications. Some of these processes may require assistance form third-party laboratories which can further increase the costs. The burden of meeting these requirements impedes innovation. In addition, solar certification standards (e.g. UL and IEC) are developed for rack-mounted conventional PV technologies making it difficult for BIPV products to comply. Similarly, the certification and testing process of building products developed for traditional passive building products and is not designed for BIPV. There is, therefore, no clear path for a BIPV company to adhere to guidelines while being innovative. BIPV deserves to be considered as an independent category with dedicated standards that trim away aspects not relevant but burdensome to the technology developers.
Regarding permitting barriers, it appears that local regulations have not caught up with BIPV technologies and there are no codes or standards specifically addressing BIPV. Given BIPV products are rapidly evolving, there is a mismatch with the fire, electrical, and structural codes enforced, the newest model codes, and the newest BIPV products. NEC code requiring rapid shutdown, voltage limitations of 80V, and fire set-back requirement were mentioned as relevant examples. These challenges continue to the inspection phase of the permitting process, where the inspector enforces the code implemented at the local government. BIPV may face challenges if the inspection process and sequence is not explicitly understood by jurisdictions and builders alike. Variations and inconsistencies from multiple revisions of codes and interpretation of inspectors are also frequent. This reality results in delays and inefficiencies that influence BIPV product installation processes, timelines, and costs.
Another impediment referenced by respondents are utilities placing maximum PV limitations per account, which limit a portion of the value proposition needed to advance adoption.
Respondents indicated that there are significant information and knowledge gaps in the industry that mainly relate to either limited awareness of the BIPV technologies and their full potential by specific groups of impacted stakeholders or the fact the BIPV industry sector is currently siloed, and each group of stakeholders has limited visibility and understanding of the state and activities of other groups. More opportunities for open discussion between silos are greatly needed and taking the discussion to other professional forums would be most useful. End-users or impacted stakeholders also operate under the mindset of segregating the structural aspects from the energy generation aspects of buildings, viewing them as two separate types of activities and not considering more comprehensive and holistic approaches. Respondents also identified specific groups of stakeholders, where knowledge and information gaps appear to be more prominent. The key groups identified include (i) architects/designers, (ii) builders/contractors, (iii) asset owners/operators, and (iv) regulators.
Specific lack of knowledge and informational gaps have been identified in each of the following areas:
Respondents have identified a variety of stakeholder groups that are considered underrepresented in current conversation related to BIPV technologies. Increasing active engagement from such groups could improve the exchange of information and alleviate some of the identified challenges of BIPV adoption. Such underrepresented stakeholder groups include:
It was also noted by the respondents that in order to increase the acceptance of BIPV, a more wholistic view of the market needs to be developed rather than focus on individual segments. &#;Siloed&#; approaches to market sectors have resulted in a lack of clarity of BIPV market needs and lack of communication and exchange or information between these segments. An approach that allows for cross-pollination between these segments and viewing BIPV under a system-design (or building-design) approach, rather than individual component designs could provide stronger potential for the industry sector.
Respondents have recommended a variety of mechanisms that could be developed and used to effectively engage interested stakeholders in the BIPV space allowing for better exchange of information and addressing some of the identified challenges of BIPV adoption. Such mechanisms include:
The following information was contributed by imec and adapted for Solar Power World.
What is BIPV?
Traditionally, solar is mounted on a building&#;s roof, referred to as building-applied PV. But more architects are learning how to also incorporate solar cells and modules into things like curtain walls, roof tiles and railings known as building integrated photovoltaics (BIPV).
A BIPV system consists of solar cells or modules that are integrated in building elements or material as part of the building structure. This way, they replace a conventional building element, rather than attaching to one. BIPV modules not only generate electricity, they can also provide added functionality to the building. For example, they can provide sun protection, thermal insulation, noise protection or safety.
Where can BIPV be installed?
BIPV provides several benefits when compared to traditional solar panels. First, there are more available surfaces for integrating the solar cells or modules &#; BIPV is not limited to roof integration. Solar modules can also be integrated into the building&#;s facade, skylights, railings and more. BIPV also adds to the aesthetics of the building. For example, the materials used for BIPV allow architects to play around with transparency and color. When integrated in ventilated facades, semi-transparent skylights or windows, BIPV can help keep the building cool.
What are the costs associated with BIPV?
In general, BIPV is more expensive than traditional PV systems used for solar power plants. There is some logic to this since the BIPV system has more functions than only delivering electrical power. However, because BIPV serves multiple functions in a building besides producing power, it may save material and installation cost.
What technologies are involved with BIPV?
The main solar cell technologies for BIPV are crystalline silicon solar cells, thin-film silicon solar cells and other thin-film technologies like organic solar cells (OPV) and dye sensitized solar cells (DSC). Crystalline silicon solar is the most mature technology, though thin-film technologies are grabbing a lot of attention because of their flexible character, ease of integration and better response to indirect light.
Organic solar cells are a relatively new technology that is still in the development phase. However, advantages of OPV can be that it&#;s a light-weight semi-transparent material, it can be coated inexpensively onto curved surfaces and onto glass, and it can be made in various colors or just color neutral. It also has a superior sensitivity to low light intensities, making the technology fit for maritime climates. Also, the technology is less dependent on the incident sunlight angle, which makes it ideal for aspects such as facade integration.
What is the outlook for the BIPV market?
BIPV is still a niche market, but architects are starting to use BIPV elements more frequently in the design of new public and office buildings. New net-zero energy buildings will help drive BIPV demand. According to Pike Research, BIPV is expected to become one of the fastest growing segments in the PV sector with up to 4.6 GW of installations forecast through .
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