Only 2%! Why is BIPV still not being applied on a large scale?

22-04-2021

Only 2%! Why is BIPV still not being applied on a large scale?



In the past ten years, the rapid growth of photovoltaics has reached a global market of approximately 100 GWp installed annually, which means that approximately 35 to 400 million solar modules are produced and sold annually. However, integrating them into buildings is still a niche market. According to the latest report of the EU's Horizon 2020 research project PVSITES, only about 2% of the installed PV capacity was integrated into buildings in 2016. This trivial figure is particularly eye-catching when one considers more than 70% of energy consumption. The carbon dioxide produced worldwide is consumed in cities, and about 40% to 50% of all greenhouse gas emissions come from urban areas.


In order to meet this greenhouse gas challenge and promote on-site power generation, the European Parliament and Council introduced Directive 2010/31/EU on the energy performance of buildings in 2010, the concept of which is "Near-Zero Energy Buildings (NZEB)" . The directive applies to all new buildings constructed after 2021. For new buildings to accommodate public institutions, the directive came into effect at the beginning of this year.


No specific measures are specified to achieve NZEB status. Building owners can consider various aspects of energy efficiency, such as insulation, heat recovery and power saving concepts. However, since the overall energy balance of a building is a regulatory goal, to achieve the NZEB standard, the production of active power in or around the building is essential.


Potential and challenge


There is no doubt that the implementation of PV will play an important role in the design of future buildings or the transformation of existing building infrastructure. The NZEB standard will be a driving force to achieve this goal, but it is not alone. Building Integrated Photovoltaics (BIPV) can be used to activate existing areas or surfaces to produce electricity. Therefore, no additional space is required to bring more PV into the urban area. The potential for clean electricity generated by integrated photovoltaic power generation is huge. As the Becquerel Institute discovered in 2016, the potential share of Germany's BIPV power generation in total electricity demand exceeds 30%, and even about 40% for more southern countries (such as Italy).


But why are BIPV solutions still playing a marginal role in the solar business? So far, why are they rarely considered in construction projects?


In order to answer these questions, the Helmholtz-Zentrum Berlin Research Center (HZB) in Germany organized a seminar last year and communicated with stakeholders in all areas of BIPV to conduct a needs analysis. The results show that it is not a lack of technology itself.


At the HZB seminar, many people from the construction industry are implementing new or refurbishment projects, and they acknowledged that there is an awareness gap in BIPV's potential and supporting technologies. Most architects, planners and building owners simply do not have enough information to integrate photovoltaic technology into their projects. As a result, there are many reservations about BIPV, such as attractive design, high cost, and prohibitive complexity. In order to overcome these obvious misunderstandings, the needs of architects and builders must be put first, and the understanding of how these stakeholders view BIPV must be the focus.


Function and style


BIPV is characterized by the fact that solar modules are an integral part of the building skin and therefore become a multifunctional building element. In addition to generating electricity, the component must now also assume other functions of the building's exterior wall.


The most well-known alternative to traditional roof installations is solar modules, which are functionally and aesthetically integrated directly on the roof. Therefore, these components can not only generate electricity, but also act as a roof to protect against wind and rain. If visible, in the case of a sloping roof, solar modules will also affect the appearance of the building. The diversity of conventional roof elements also requires PV active elements with a high degree of variability in shape, color and appearance. Large-area, homogeneous glass-glass modules are required, as well as small systems, such as roof tiles, whose shape and color match perfectly with conventional roof tiles.


Similar standards are also valid for solar modules used as external wall elements, but here, aesthetic quality is particularly important. There are various types of PV active facades. Solar modules installed as ventilated cold facades can easily replace traditional elements of ventilated curtain walls. But the solution can also be used as a warm façade element, for example by sticking directly to the façade. In addition to weatherproofing, thermal insulation or sound insulation are other attributes that PV active facade elements can provide.


Regarding the aesthetic function of the facade elements, there are already different concepts on the market. The color components range from anthracite/black to gray, blue, green, yellow and even "golden". For example, these colors can be achieved by using a special front glass containing a nano-layer structure. It is important that the power output of this type of module is not excessively reduced. Compared with the traditional module with transparent front glass, its initial power output can reach more than 80%.


An alternative to using this special front glass is ceramic printing. This technology achieves uniform colors and another feature that architects like: the potential to print almost any structure or picture on top of the module. In fact, this function makes the solar cells that make up the module almost invisible to the observer. However, this printing does affect the final power output more strongly. But because solar cells are almost completely invisible, this technology can also be applied to high-power crystal modules, so it can be used as an architectural element with high aesthetic value and high power.


The third technique for creating colored BIPV elements is to use colored foils. The cost of this technology is lower, and more importantly, it allows almost any color. Thanks to this function, researchers at the Swiss Center for Electronics and Microtechnology (CSEM) are able to develop white solar cell modules. In principle, this kind of development can "activate" a large number of conventional white facades in the world.


Integrating solar cells or modules into shading elements is an attractive way to combine sun protection and energy production. For example, this can be achieved by using glass with a very thin, uniform coverage of active photovoltaic material. Thin film technologies such as organic semiconductors (OPV), CIGS (copper indium gallium selenide/sulfite) or thin film silicon are very suitable for such applications.


Alternatively, if crystalline silicon cells are arranged in a pattern in a glass-glass module or have a large gap between the cells, translucency can also be achieved by using crystalline silicon cells. This concept is used in overhead installation systems together with vertical glass curtain walls. It can also be installed in a movable shading device to reduce sunlight at certain times of the day.


All these methods prove the way that BIPV solar modules can provide additional functions and solve aesthetic problems, making them more attractive to architects. However, compared with conventional output optimization modules, they are also accompanied by a certain degree of power output reduction. Despite the power loss, their aesthetic and functional advantages still make them attractive to the construction industry, and the construction industry’s emphasis on power generation optimization has been greatly reduced. In view of this, BIPV elements should be benchmarked against conventional non-electrical building elements.


Change mindset


BIPV is different from traditional rooftop solar systems in many aspects. Traditional rooftop solar systems do not require multi-functions, nor do they consider aesthetics. If developing products for integration into architectural elements, manufacturers need to reconsider. Architects, builders and users of buildings initially expected to implement conventional functions in the building skin. From their point of view, power generation is an additional property. In addition, developers of multifunctional BIPV elements must also consider the following:


Develop cost-effective customized solutions for solar-active building elements with variable size, shape, color and transparency;


Setting standards and attractive prices (ideally can be used for established planning tools, such as building information modeling (BIM);


Integrate photovoltaic elements into novel facade elements through the combination of building materials and energy generating elements;


High elasticity against temporary (partial) shadows;


Long-term stability and long-term stability and degradation of power output, and long-term stability and degradation of appearance (such as color stability);


Develop monitoring and maintenance concepts to adapt to the specific conditions of the site (consider the installation height, replace defective modules or facade elements);


And meet the legal requirements of safety (including fire protection), construction law, energy law and other legal requirements.


The issue of regulatory compliance is a challenge for all stakeholders. Building codes and regulations in the energy industry usually depend heavily on local regulations. Not only are they different from country to country, but they often deviate significantly from each other in different states, cities, and even local communities. However, it is not only necessary to adapt to the solar energy industry.


The construction industry must be aware of its responsibility to society as a whole. Both new construction and renovation projects must explicitly consider energy consumption and on-site power generation. Architects and construction personnel must be willing to use new materials and elements that provide additional power generation functions. They also need to accept the changes in their regular planning process, because the electrical aspects must be considered at the concept stage.


Narrowing the gap


Integrating photovoltaic power generation into buildings is a challenge for all stakeholders. Not only are there knowledge about technology and possibilities, but there are also gaps between cultures. In order to bridge these gaps, a bridge must be built between the construction world and the energy world. The challenge must be managed by everyone: architects and planners; material and component manufacturers; and research and development departments. These challenges are usually new challenges for all participants and are affected by existing biases. These are multifaceted challenges, and in essence, they can only be dealt with together after accepting a change in thinking.






Get the latest price? We'll respond as soon as possible(within 12 hours)

Privacy policy