Building Integrated Photovoltaics: An emerging market

The segment of building-integrated photovoltaics (BIPV) is finally beginning to emerge in the marketplace after more than 20 years of R&D and fancy showcase projects, due to the vision of leading solar technology and material developers such as Dyesol, Schott Solar, Scheuten Solar, SunPower, and Suntech. In cooperation with the market research company Greentech Media Research (GTM Research) Solar Server's solar report in August 2010 highlights new developments in technology, political framework and international markets. Exciting new products that incorporate PV modules into actual building materials such as curtain walls, windows, and roofing shingles are now available from a variety of developers in the BIPV supply chain.

Solar façade with CIS thin film panels by Sulfurcell (courtesy: Sulfurcell)
PV roof with laminates by Centrosolar (courtesy: Centrosolar)

Earlier generations of PV for buildings utilized solar panels mounted directly onto the building roof with minimal aesthetic considerations. This concept was replaced by building-integrated PV systems, where the PV modules actually came to replace parts of the building envelope, providing functional considerations and lowering costs. More recently, thin-film PV technologies have begun to enable the seamless integration of PV onto buildings, and will likely succeed in markets where their superior flexibility, minimal weight, and improved ability to perform in variable lighting conditions gives them a significant competitive advantage over conventional solar technologies. 

However the success of creating new BIPV markets will depend on many variables, including:

1. Concerted efforts by players in the BIPV supply chain to work together towards the design and integration of solar into the building envelope;

2. Costs in $/Wp, as well as the building industry’s preferred metric of $/m2, of product and power availability;

3. Development of specific standards and building codes;

4. Availability of federal and local incentives to ensure cost effectiveness;

5. Added value for consumers and architects; and

6. Ease of production and the scale at which a production plant becomes economically feasible.


Incentive schemes in favour of BIPV

For some time, thin-film solar technologies have not been at a price point to make them truly competitive with conventional solar-based panel systems that are just "slapped" onto buildings, but this is changing due to the current round of incentive schemes, and GTM research expects that thin-film solar technologies will soon play a significant energy role in both the applications and the markets in which conventional solar materials are currently employed, as well as in markets where conventional solar materials are unsuitable for various reasons, such as façades, roofs and window applications.


A definition of BIPV and BAPV

There is some confusion regarding the definition of BIPV within both the PV industry and the building industry. GTM Research defines BIPV as building-integrated PV, which requires that the building team along the entire supply chain - including architects, building designers, engineers, building owners and utility companies - work together to design and build the photovoltaics into the building’s very "skin" as an element, from the inception of the project onwards. BAPV, on the other hand, is defined as building-applied PV. In this process, the photovoltaics are a retrofit, added to the building after construction is completed.


Roof-intergrated PV system (Berlin central railway station, courtesy: BSW Solar, Langrock)
Suntech's headquarter with PV façade (courtesy: Suntech)

Buildings to turn into energy-producing structures

A number of factors limit the BIPV market. It is a clean technology that has been around for more than 20 years, and until recently, the market for this product was a relatively small and underdeveloped niche. BIPV manufacturers predominantly used mature but costly crystalline silicon-based systems, which were added to the building envelope retroactively and often performed poorly, especially in areas of minimal sunlight and/or high temperatures.

The development of thin-film flexible solar modules promises to be a major benefit to the BIPV market, since such modules will offer far better performance, as well as varying degrees of transparency and multiple color options. This will provide designers the opportunity to expand traditional architecture and transform buildings into aesthetically pleasing, energy-producing structures.

However, several issues need to be resolved before the industry can advance to that point. Current obstacles include challenges such as optimal system orientation, weatherability, lifetime, the development of specific standards and building codes, as well as performance and cost-competitive pricing. In order to address these issues satisfactorily, all developers in the supply chain will need to work together to improve generating efficiency, as well as to reduce production and distribution costs. As the cost of PV modules continues to fall, this will likely have an enormous knock on effect towards the potential use of BIPV, since there is a need to maximize energy efficiency within the building’s energy demand in order to optimize the entire energy system and costs.


DOE estimates that up to 50% of the United States’ energy needs could be met by using BIPV systems in the long run

The demand for BIPV systems is expanding in the global construction materials market due to their reduced energy demands and overall reduced carbon footprint. In the years ahead, rising energy prices and the global focus on climate change will lead to an increased use of BIPV. Currently, the PV market generates less than 0.5% of global electricity. With the increasing use of BIPV, the U.S. Department of Energy estimates that up to 50% of the United States’ energy needs could be met by using BIPV systems in the long run, and similar results are possible elsewhere in the rest of world. Thoughtfully developed feed-in tariffs need to be devised and implemented in the major solar markets to encourage the use of comparatively costly BIPV systems in both commercial and residential settings.

The BIPV market is poised to advance rapidly; however, GTM Research believes that in order for this to happen, some critical questions first need to be answered.


What are the barriers inhibiting market development and expansion?

In order for the BIPV market to achieve sizable growth and bridge the existing gap between the PV industry and the building industries, a number of key barriers must be addressed.


Technical barriers and standards

New BIPV products that mirror the look and functionality of conventional primary building materials as a single integrated material require their own standards, and cannot rely upon existing PV and building product standards, since there are few if any performance-related standards that apply specifically to BIPV products. However, the major standards organizations around the world are working to change this situation. The introduction of E.U. Eurocodes and new standards from bodies such as International Electrotechnical Commission (IEC), Underwriters Laboratories (UL), and American Standards Test Method (ASTM) will address building materials, architectural, safety and electrical issues, as well as long term performance issues. BIPV producers have developed their own standard-sized modules, which in some cases can cause structural overload of existing buildings, as BIPV modules can be quite heavy.

The state of California was one of the first states to develop a green building standards code, known as "CALGreen", which will mandate that new buildings in the state be more energy - and environmentally efficient. This code will also help the International Code Council develop the new International Green Construction Code (IGCC) for commercial buildings, which will be published in 2012.


Legal and administrative barriers

Until very recently, it was not possible to use BIPV on listed or historic buildings. BIPV is not yet defined as an energy-efficient technology in many jurisdictions, and as such, it is subject to an array of complex planning policies and procedures.


Market barriers, different units of measurement

BIPV is still too costly, especially when compared with its rival technology, building-added PV (BAPV), since its added value as a multifunctional building element is only now beginning to be recognized. One issue that complicates the cooperation between the PV industry and the building sector is the fact that the two sectors use completely different units of measurement: architects and planners typically use kWh/m2, whereas the PV community routinely uses kWh/kWp. It turns out that many construction stakeholders and investors are not familiar with the concept of watt power, and would prefer to estimate the price of PV modules based on $/m². For the moment, this is not such a straightforward process, since BIPV modules are not mass-produced, but are custom-built to order and therefore pricing varies significantly for each installation.


Perception barriers and acceptance

The advantages of BIPV for architects and end-users are still not clearly defined, and some do not view the inherent aesthetic capabilities of the technology as a potentially valuable asset because they feel the underlying PV technology is outdated. This may be due to a lack of information on their part, or an outgrowth of the widely recognized fact that electricity consumption has come to play an increasingly important role in the value determination of buildings. In order for the BIPV market to grow, there needs to be greater acceptance from the construction sector and end-users alike, as well as a greater willingness to integrate PV from project inception through the entire construction process.


PV facades with modules by Sulfurcell (left) and Schott Solar (right)
PV facades with modules by Sulfurcell (left) and Schott Solar (right)

What application areas look most promising for BIPV?

Aesthetics have long been a complaint of homeowners who are interested in switching to renewable power but were unhappy with the bulky look of conventional solar panels. Today, BIPV solar installations are able to serve as functional building materials in a number of applications, such as façades (cladding and curtain walls), roofing (solar tiles, slates, shingles and single-ply membranes), and windows (glazing, skylights and sunshades).

Given that BIPV use is so deeply intertwined with the construction industry, BIPV products are most cost-effective when used in new residential or commercial projects. The retrofitting of existing structures with BIPV products also benefits from this relationship, but represents a smaller growth opportunity. Advancing technologies such as CIGS, DSC, and OPV solar cells are able to offer almost invisible solar coverage; the emerging opportunities for these materials are summarized in Table E-2 at the end of the article.


Number of housing starts to expand

Despite a bright long-term outlook for BIPV, new construction starts and reroofing projects were slow during 2009 and into 2010. This has negatively impacted supplier sales, even for leading BAPV suppliers such as United Solar Ovonics through its traditional building-material channels. However, the economy will soon likely pick up and business will improve – provided that the construction industry picks up again and consumers start to come face-to-face with rising energy costs. According to the U.S. Congressional Budget Office, the number of housing starts in 2008 was 1.53 million, a figure that is expected to increase to 1.56 million in 2010 and then further expand to 1.58 million by 2012.


"New" thin films to hit the market

To counteract this decline, some suppliers (such as Sharp, Sunpower, and United Solar) have resorted to introducing new BAPV systems to the market, in order to expand near-term addressable markets beyond traditional BIPV. With this in mind, United Solar Ovonics recently launched a tilt BAPV product for rooftop retrofits, which leverages the lightweight attributes of BAPV’s flexible amorphous silicon laminates, as well as a high energy yield that results in competitive levelized energy costs and attractive returns. The first wave of "new" thin-film products are due to hit the market in late 2010 or early 2011 from developers like Ascent, Odersun, Corus Colors, Dow Solar, and SKYShades.


Low cost and high cost BIPV

The building envelope naturally offers several opportunities for the "integration" of solar technology. These include roofs (one of the first application methods explored in the late 1980s), walls, building skins, and windows - the so-called eyes of the building (see Figure 3-1). Different markets are available for BIPV products, the two most significant of which are broadly classified as low cost (which can utilize standardized building products) and high cost (which requires customized building products).

GTM Research believes that BIPV systems could contribute significantly to the future growth of the solar market. These systems are relatively new, and improved aesthetics, along with cost reductions, can be attained by embedding thin-film PV directly onto the building materials in new construction.


Selected market activities on roofing; solar tiles and shingles

A number of BIPV developers are active in the solar roofing market segment, including United Solar Ovonics, Dow Solar, Applied Solar, Corus Colors, and the Victorian Organic Solar Cell Consortium. Perhaps the most popular integrated system in the U.S. consists of PV modules using mono- or polycrystalline cells to replace conventional cement tiles. These PV tiles are installed on roofs in a way that blends in with cement tiles, following the contours of the roof. In many cases, one module can replace up to three or four tiles, and reduce the number of necessary connections. The PV array weighs less than the cement tiles, but the roof has to be engineered for the correct weight and compliant with local and national roofing requirements, since it represents the first line of defense against the weather.


Solar Shingles "Power Ply" and "S Tile" by Lumeta
Solar Shingles "Power Ply" and "S Tile" by Lumeta
courtesy: Lumeta

Shingle systems are similar to thin-film laminates, and by taking advantage of thin-film technology, can be used to replace asphalt shingles. This more lightweight plastic shingle replacement comes in long strips to replace courses of asphalt shingles and to reduce the number of electrical connections. The most significant commercially available amorphous asphalt shingle replacement today is the Uni-Solar shingle made by United Solar Ovonics, which is applied over a fire-resistant roof membrane. However, this market configuration may well change with the commercial launch of Dow Solar’s Powerhouse solar shingle and Lumeta’s Lumeta Solar S and Solar Tiles in the near future. 


Wall Applications

Recent years have seen a rapidly growing interest among contemporary architects in the use of curtain walls to create innovative, attention-grabbing building façades. With new concerns about the environment and a focus on developing affordable building envelopes, the curtain wall represents a microcosm of the issues that are important to architecture: climate responsiveness, energy use, the intelligent utilization of resources, and advancements in digital design and fabrication.


PV façade system "ARTLine Invisible" by Würth Solar
PV façade system "ARTLine Invisible" by Würth Solar

Building façades themselves are already expensive, so curtain walls may be able to compete in this arena. The incremental cost to add PV to the curtain wall is not likely to be prohibitive, either in new construction or retrofit projects. 

A number of interesting developments in this growing niche are worthy of mention, especially with respect to leading developers AltPower, Arch Aluminum, Konarka Technologies, Schüco, Schott Solar, SolarFrameWorks, and Würth Solar.


Power Plastic integrated into a wall structure set

Arch Aluminum & Glass i.e. launched the first curtain wall pilot project using Konarka’s Power Plastic OPV material into a wall structure set alongside Arch’s offices in Florida (see Figure 3-5). The solar panels will provide 1.5 kilowatts of power generation capacity and were fully operational by the end of 2009. The curtain wall is an array of solar panels, glass, and aluminum, with a peak output of approximately 40 watts per panel. After more extensive testing, the project’s data will be shared with architects, building developers, and owners, as well as alpha and beta field-testing customers to be selected in 2010-2011. For the commercial products, it is anticipated that the solar panels would become the curtain walls, or the building’s façade. This use of the technology will serve to promote the use of colored glass photovoltaics.


OPV-based curtain wall: Courtesy: Konarka Technologies, Inc.
OPV-based curtain wall: Courtesy: Konarka Technologies, Inc.

Konarka also plans to make a transparent version of its colorful films available during 2010. The company’s researchers developed the transparent films only this year; part of the development pact with Arch calls for Konarka to improve the performance of the transparent films, and we know that Konarka has committed to improving efficiency by a minimum of 30% per year.


In which global regions will BIPV be most likely to succeed?

As expected, the best BIPV markets parallel the best markets for PV modules, as summarized in Table E-3 below. In Europe, the solar industry is largely dependent upon short- to mid-term government incentives, such as feed-in tariffs. Germany has been the primary driving force behind the growth of the global BIPV industry with its well developed infrastructure, but this will likely change in the near future.

Suppliers will have to refocus on other first-tier countries where the BIPV market is still small, such as France (which plans to increase solar significantly, with a particular focus on deploying BIPV for homes, schools and hospitals [€0.58/kWh]) and Italy (which is also placing emphasis on built-in PV, with tariffs for BIPV systems likely to receive 25% more than a non-BIPV equivalent project). In North America, BIPV is mostly concentrated in California, followed by New Jersey, with Ontario (Canada) also being a market that is expected to pick up in the near future.



The feed-in tariffs shown in the following Figure represent some of the highest feed-in tariffs based on power output levels.



Second-tier countries that will likely develop BIPV markets include Belgium, Greece, Portugal, Switzerland, and Slovenia. All of these countries have favorable BIPV feed-in tariffs, which will incentivize market development to support significant growth by 2012. To encourage the use of BIPV in Japan, the government is providing €410 million to resume its residential PV program, especially for small systems of less than 10 kW power (with a feed-in tariff of €0.39 kW/hr) and commercial programs (feed-in tariff of €0.20 kW/hr). 


Are low-efficiency solar technologies able to compete with high efficiency solar technologies for typical BIPV applications?

BIPV is one of the fastest growing segments of the solar industry, especially in Europe, due in part to demand from architects, designers, and building developers. Until recently, aesthetic and performance concerns limited the ability of architects to use BIPV technology in their designs, but this is all changing with the emergence of energy efficient and transparent solar materials that offer superior performance and multiple color options.

With these features, BIPV will no longer need to be confined to spandrel or overhead applications using conventional silicon solar technology; rather, an entire building envelope can be put to use, allowing the structure to produce its own power using flexible thin-film materials (as shown in Table E-4).


Flexible thin-film solar materials to ease installation

Conventional solar technology made using crystalline silicon accounts for about 85 % of the solar market. As the most mature and widely used material for BIPV, most solar panels utilized for façades, curtain walls and roofs are made from this material. However, it is not necessarily the preferred material for building integration, even though its cost and performance are favorable, because of its aesthetics and a lack of flexibility.

Flexible thin-film solar materials, such as amorphous silicon, cadmium tellurium, CIGS, dye sensitized cells, and organic photovoltaics are far easier to use to integrate PV directly into architectural features such as building façades, roofs, and windows. These new materials offer a lower cost alternative as a function of the reduced material requirements and energy usage used in their manufacture as compared with conventional materials.


New low cost production technologies

Until recently, they could only be applied directly to building materials in a manner similar to the installation method used for most BAPV products, but can now be fully integrated into the material using other techniques such as low cost printing or spraying. Builders appreciate the ease of working with rolls of such materials and they will no doubt come to be widely used, once a number of lingering technology and cost issues are resolved. It should be noted that BIPV is currently positioned as a very high-end building technology, but given its multifunctional nature and eventual plans for mass manufacture, its cost will likely come down.

Amorphous silicon is the most frequently installed thin-film material, with the majority of current capacity coming from United Solar Ovonics. Uni-Solar, the company’s flexible "peel and stick" amorphous silicon-based solar materials (BAPV), realizes module efficiencies up to 8%, and it is expected that third-generation technology could produce panels with 10% efficiency.


Dow Solar’s CIGS-based "POWERHOUSE" solar shingle
Dow Solar’s CIGS-based "POWERHOUSE" solar shingle

CdTe promises higher efficiencies and lower costs than amorphous silicon, however - competing firm First Solar’s panels realized 11.1 % efficiency, and module cost was about $0.84 per watt by early 2010. Dow Solar’s TCIGS-based solar tile product, due out in late 2010, is set to receive $140 million support from Michigan Economic Development Corporation, which is a huge endorsement of this technology platform, as well as for the evolving BIPV market as a whole.



Dyesol is taking a leading role in developing and commercializing building-integrated products based on dye-sensitized cell technology. The company’s partnership with Corus Colors has reached the alpha model period, and this will ultimately lead to the commercialization of DSC-coated metal sheet for roofing applications by 2011.

Dyesol has positioned itself well, creating subsidiaries in the major solar markets that are rife with buildings awaiting PV integration, including Germany, Italy, Japan, South Korea, the U.K., and the U.S.


Left: Dye Solar Cell by Dyesol. Right: Konarka's Power Plastic
Left: Dye Solar Cell by Dyesol. Right: Konarka's Power Plastic

OPV and BIPV look like an attractive match whereby large rolls of OPV could be placed on warehouse rooftops, a model that potentially represents a huge global market. In the United States, wooden roofs that cannot bear the load of silicon PV are commonplace, so architects using OPV would be able to provide added value to their customers. In Asia, Innovia Films and Bosch plan to join the Australian-based Victorian Organic Solar Cell Consortium this summer to help further develop and commercialize the group’s OPV technology.


GTM Research recently published the market report “Building-Integrated Photovoltaics: An Emerging Market”:

Questions the Report Addresses:
• What are the barriers inhibiting market development and expansion?
• Which application areas look most promising for BIPV?
• In which global regions will BIPV be most likely to succeed?
• Are low-efficiency solar technologies able to compete with high-efficiency solar technologies for typical BIPV applications?

Key Elements of the Report:
• BIPV technologies, materials, and products
• Markets and applications (roofing, walls, facades, windows, and others)
• BIPV policy assessment and leading global markets
• Distribution channel developments and economics
• Key players in the BIPV supply chain (incl. 50 profiles)
• Comprehensive BIPV product list by supplier and cell manufacturer

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