Building Integrated Photovoltaics, also known as BIPV, are photovoltaic materials that can be directly embedded inside conventional parts of the building envelope, for example in a building’s roof, skylights, window overhangs and exterior wall façades. Once these photovoltaic materials are embedded, they can serve as primary or secondary sources of power to the building as they make use of the sun’s energy. BIPV today offers a very viable alternative to traditional building materials as this technology is increasingly being used in the construction of new buildings. Existing buildings can be retrofitted with BIPV as well. To the homeowner or the building investor who wants to go solar on the entire building, use clean energy and save on monthly electric bills, this is a very attractive option.
But there is another reason for its popularity: low initial cost. Other than simultaneously serving as the building envelope material and a power generator, a big advantage of using integrated photovoltaic materials in place of traditional materials in a building is that it reduces the initial cost by lowering the amount spent on materials and labor than would have otherwise been utilized with conventional building processes. This single factor alone makes BIPVs one of the fastest growing segments of the PV industry today.
BIPV Design Considerations
A BIPV system’s design has to be carefully planned and must take into account various factors like the building’s intended use, electrical loads, its location and orientation, the relevant building and safety codes, the utility provider’s own costs and issues and PV efficiency among other things. As an example, providing adequate ventilation is important during the BIPV process for maintaining the PV conversion efficiencies. When embedded in a building, PV efficiencies usually get reduced at elevated operating temperatures. To prevent or offset this from happening, the design should allow for appropriate ventilation behind the modules. Another consideration when designing BIPV is to compare the peak building loads to the peak power outputs of the PV array. The analysis may reveal that an alternative backup should be integrated into the system to offset the most expensive power demand periods for the building. As another option to optimize system efficiency, a designer may also choose to capture and reuse the solar thermal resource that is developed through the heating of the modules. This can be a very attractive option specially when installing BIPV in cold places.
Another important design consideration is planning the orientation of the embedded PV array. Different orientations can have significant impact on the annual energy output of the system. Tilted arrays in a BIPV system usually generate 50% – 70% more electricity than a vertical façade would do. Similarly, shading effects must be considered for the design. For example, the system should be completely un-shaded for at least 3 hours on either side of the solar noon. The impact of shading is directly related to the output of the BIPV array. Designers also need to carefully consider the impacts of the local environment and climate to the PV array output. For example, cold and clear days will increase the energy output of the array, while hot and overcast days can reduce the output. The BIPV arrays must be designed for potential snow and wind-loading conditions. As an example, proper tilt angles can help shed the snow faster. At the same time, surfaces like snow that reflect light can further increase the energy output of the array. This implies that a judicious mix of advantages should be considered when choosing the tilt angle keeping in mind local conditions for the building. Similarly BIPV arrays should also be designed for dry and dusty areas where constant washing may be required to control the efficiency losses.
As a general design practice, all loads experienced by the BIPV system in the building should be minimized wherever possible. Energy efficient motors should be deployed and designers should consider other such peak reduction strategies for the BIPV system. Also, since the BIPV technology is relatively new, all design, installation and maintenance professionals should be properly trained, licensed and experienced in PV systems work. Aesthetically, BIPV systems can be designed to blend with traditional building materials and designs, or they can be used to create unconventional futuristic looks, based on the choice of the building owner. Semi-transparent arrays of spaced crystalline cells can provide diffuse and interior natural lighting.
BIPV Research and Public Awareness
Solar Decathlon 2009 Home by Team Germany The U.S. Government believes that PV should be a widely accepted technology in the 21st century with increasing number of solar powered homes and business that support and showcase the use of PV technology. The use of BIPV is supported by the Government in two distinct ways, i.e. by research and by raising awareness. BIPV technology is actively researched and improvised in many organizations like the National Renewable Energy Laboratory (NREL) where BIPV researchers investigate how to improve system reliability and reduce costs and utility transmission losses while further improving the market acceptance of this technology.
At the same time, the U.S. Department of Energy Solar Decathlon organizes the Solar Decathlon annual event, where 20 collegiate teams throughout the U.S. are challenged to design, build and operate solar- power homes that are cost-efficient and energy efficient while being attractive to the market. These teams spend about 2 years and design solar-powered homes that showcase technologies like BIPV to the world during these annual events. The decathlons are essential for not only motivating the emerging breed of students and engineers to think more about solar powered homes, but also in raising general public awareness, as people come, see and learn about these houses during these competitions. BIPV as a technology is a very cost effective way towards building energy efficient homes and business establishments in our communities and societies. With properly guided design, ongoing research and increasing public awareness, BIPV can become a very effective medium to showcase solar technology and to increase its widespread use in the future.
But there is another reason for its popularity: low initial cost. Other than simultaneously serving as the building envelope material and a power generator, a big advantage of using integrated photovoltaic materials in place of traditional materials in a building is that it reduces the initial cost by lowering the amount spent on materials and labor than would have otherwise been utilized with conventional building processes. This single factor alone makes BIPVs one of the fastest growing segments of the PV industry today.
BIPV Design Considerations
A BIPV system’s design has to be carefully planned and must take into account various factors like the building’s intended use, electrical loads, its location and orientation, the relevant building and safety codes, the utility provider’s own costs and issues and PV efficiency among other things. As an example, providing adequate ventilation is important during the BIPV process for maintaining the PV conversion efficiencies. When embedded in a building, PV efficiencies usually get reduced at elevated operating temperatures. To prevent or offset this from happening, the design should allow for appropriate ventilation behind the modules. Another consideration when designing BIPV is to compare the peak building loads to the peak power outputs of the PV array. The analysis may reveal that an alternative backup should be integrated into the system to offset the most expensive power demand periods for the building. As another option to optimize system efficiency, a designer may also choose to capture and reuse the solar thermal resource that is developed through the heating of the modules. This can be a very attractive option specially when installing BIPV in cold places.
Another important design consideration is planning the orientation of the embedded PV array. Different orientations can have significant impact on the annual energy output of the system. Tilted arrays in a BIPV system usually generate 50% – 70% more electricity than a vertical façade would do. Similarly, shading effects must be considered for the design. For example, the system should be completely un-shaded for at least 3 hours on either side of the solar noon. The impact of shading is directly related to the output of the BIPV array. Designers also need to carefully consider the impacts of the local environment and climate to the PV array output. For example, cold and clear days will increase the energy output of the array, while hot and overcast days can reduce the output. The BIPV arrays must be designed for potential snow and wind-loading conditions. As an example, proper tilt angles can help shed the snow faster. At the same time, surfaces like snow that reflect light can further increase the energy output of the array. This implies that a judicious mix of advantages should be considered when choosing the tilt angle keeping in mind local conditions for the building. Similarly BIPV arrays should also be designed for dry and dusty areas where constant washing may be required to control the efficiency losses.
As a general design practice, all loads experienced by the BIPV system in the building should be minimized wherever possible. Energy efficient motors should be deployed and designers should consider other such peak reduction strategies for the BIPV system. Also, since the BIPV technology is relatively new, all design, installation and maintenance professionals should be properly trained, licensed and experienced in PV systems work. Aesthetically, BIPV systems can be designed to blend with traditional building materials and designs, or they can be used to create unconventional futuristic looks, based on the choice of the building owner. Semi-transparent arrays of spaced crystalline cells can provide diffuse and interior natural lighting.
BIPV Research and Public Awareness
Solar Decathlon 2009 Home by Team Germany The U.S. Government believes that PV should be a widely accepted technology in the 21st century with increasing number of solar powered homes and business that support and showcase the use of PV technology. The use of BIPV is supported by the Government in two distinct ways, i.e. by research and by raising awareness. BIPV technology is actively researched and improvised in many organizations like the National Renewable Energy Laboratory (NREL) where BIPV researchers investigate how to improve system reliability and reduce costs and utility transmission losses while further improving the market acceptance of this technology.
At the same time, the U.S. Department of Energy Solar Decathlon organizes the Solar Decathlon annual event, where 20 collegiate teams throughout the U.S. are challenged to design, build and operate solar- power homes that are cost-efficient and energy efficient while being attractive to the market. These teams spend about 2 years and design solar-powered homes that showcase technologies like BIPV to the world during these annual events. The decathlons are essential for not only motivating the emerging breed of students and engineers to think more about solar powered homes, but also in raising general public awareness, as people come, see and learn about these houses during these competitions. BIPV as a technology is a very cost effective way towards building energy efficient homes and business establishments in our communities and societies. With properly guided design, ongoing research and increasing public awareness, BIPV can become a very effective medium to showcase solar technology and to increase its widespread use in the future.