Interview partner: Dr. Björn Rau, Helmholtz Zentrum Berlin, Institute Competence Center Photovoltaics Berlin (PVcomB), Deputy Head of Institute & Head of Technology PVcom B, Project Manager BAIP - Advisory Office for Building-integrated Photovoltaics.
"Integrated photovoltaics" is a topic of the hour. The necessary addition of PV capacity will have to activate considerable areas for energy generation. A great advantage is when already existing areas or areas that are to be built anyway can be used several times. Building-integrated photovoltaics (BIPV) is the oldest discipline in land-neutral energy development.
Dr. Rau, the integration of solar technology in roofs and facades has long been predicted to make the breakthrough from a market niche to widespread use. Why do the conditions currently seem particularly promising for the next step?
Dr. Rau: The building sector has a special role to play in the transformation to a climate-neutral society. It is responsible for around 30 % of all CO2 emissions in Germany and up to 40 % worldwide. In many places, politics and society have already recognized this importance. New laws and ordinances are being established, and subsidies are being offered for energy-efficient renovation.
In addition, there are also more and more builders and architects who are taking their role in the sustainable design of our cities and communities seriously. At the same time, the market is also offering more and more products that allow photovoltaics to be integrated into the building envelope in terms of design and thus meet the individual requirements of the building designers.
What has happened technologically in recent years? Are there any new developments to which you attribute particular importance for the further development of BIPV?
Dr. Rau: In fact, there are now a large number of technological solutions for integrating photovoltaics into the building envelope. Not only technically, but above all in terms of design. In addition to frameless solar modules in many colors and different surfaces, e.g. in the facade, partially transparent concepts are also playing an increasingly important role as shading elements in or in front of windows. Not to forget that there are also more and more suppliers of roof tiles with integrated solar modules. A possibility to integrate photovoltaics into the roof and at the same time have a typical tiled roof.
Where does the future lie - will technological innovations in BIPV modules move in the direction of "non-visibility", e.g. transparencies as with window glass, or will the module remain "readable" and also serve as a symbol for renewable energies on the building?
Dr. Rau: The strength and future of building-integrated photovoltaics will be the diversity of its integration. By this I mean its design diversity. The deliberate "technical" appearance of classic photovoltaics will play less of a role than the possibility of integrating building elements into the building envelope that can also generate electricity. Their primary task will continue to be to be a facade or roof element that fits the respective building in terms of function and design.
BIPV is seen as having great potential for value creation in Germany and Europe, as many projects use customized solutions. At the same time, however, a scaling effect will be necessary to reduce costs. How can BIPV accomplish this?
Dr. Rau: The integration of photovoltaics into a building envelope is always associated with an individual construction project. Of course, certain standards and guidelines apply, but there is a lot of flexibility in classic construction, especially with regard to the dimensions of facade elements, interfaces with other building materials and the substructure. Solar modules, by their nature, are not so easy to "tailor", especially for cost reasons. Therefore, both are in demand. Standard solar modules that are easy to plan, ideally also already with a general building authority approval, and the project-specific solutions, more complex to manufacture but with high design potential.
The former are particularly suitable for large construction projects and for recurring grid dimensions, e.g. in facades. Here, the PV industry has to offer a kind of catalog product. The latter entails higher costs, but reality shows that builders rarely go for the cheapest materials and construction elements when planning their building envelope. The facade is the face of the building. However, BIPV-related value creation does not depend on the solar module alone. Design and construction in particular is a task for architects, planners and companies that know the local market and are familiar, for example, with the rules and regulations that often apply at the local level. Successful integration also requires a closer exchange between builders and executors. The latter, by the way, is often not the solar installer alone but much more the façade builder or the roofer.
With the Advisory Office for Building-Integrated Photovoltaics (BAIP), you offer support to builders, architects and planners in the implementation of PV projects in roofs and facades. Which issues have proven to be the most important? Where would the next measures have to start in order to advance BIPV projects on a broad scale?
Dr. Rau: BAIP provides information on available technologies, products, technical and structural feasibility, and legal framework conditions for the target groups. Product neutrality and financial independence are decisive for the acceptance of the offer and also our unique selling proposition. We provide individual advice on individual building projects and we provide information in the form of training events and seminars, e.g. in cooperation with chambers of architects. The inquiries range from private owners, architectural firms, public developers, universities and housing associations to the energy industry. The variety of topics ranges from general or very specific technical and design possibilities, yield analyses, fire protection and building law to operating concepts of the owners.
For the further spread of BIPV, it is indispensable that the solar activation of buildings always considers the building envelope as a whole and not just the roof. This is unfortunately often neglected, even in current solar legislation. In addition, it is important to bring the possibilities of BIPV into the building world and to inform, encourage and support builders and architects. The PV industry needs to understand that BIPV elements are primarily building elements and only secondarily solar modules. Therefore, alliances are needed to find suitable solutions for a successful integration of photovoltaics.
Finally, the existing hurdles must be removed, because the legal framework (e.g. building law and fire protection) and also topics such as tenant electricity are often too complicated and deterrent for the individual building owner.
Interview: Fabian Flade (Office Manager Solarenergieförderverein Bayern e. V. and organizer of the Architecture Award Building-Integrated Solar Technology). July, 5th 2021