Building-integrated photovoltaics explained

Building-integrated photovoltaics (BIPV) are photovoltaic materials that are used to replace conventional building materials in parts of the building envelope such as the roof, skylights, or façades.[1] They are increasingly being incorporated into the construction of new buildings as a principal or ancillary source of electrical power, although existing buildings may be retrofitted with similar technology. The advantage of integrated photovoltaics over more common non-integrated systems is that the initial cost can be offset by reducing the amount spent on building materials and labor that would normally be used to construct the part of the building that the BIPV modules replace. In addition, BIPV allows for more widespread solar adoption when the building's aesthetics matter and traditional rack-mounted solar panels would disrupt the intended look of the building.

The term building-applied photovoltaics (BAPV) is sometimes used to refer to photovoltaics that are retrofit – integrated into the building after construction is complete. Most building-integrated installations are actually BAPV. Some manufacturers and builders differentiate new construction BIPV from BAPV.[2]

History

PV applications for buildings began appearing in the 1970s. Aluminum-framed photovoltaic modules were connected to, or mounted on, buildings that were usually in remote areas without access to an electric power grid. In the 1980s photovoltaic module add-ons to roofs began being demonstrated. These PV systems were usually installed on utility-grid-connected buildings in areas with centralized power stations. In the 1990s BIPV construction products specially designed to be integrated into a building envelope became commercially available.[3] A 1998 doctoral thesis by Patrina Eiffert, entitled An Economic Assessment of BIPV, hypothesized that one day there would an economic value for trading Renewable Energy Credits (RECs).[4] A 2011 economic assessment and brief overview of the history of BIPV by the U.S. National Renewable Energy Laboratory suggests that there may be significant technical challenges to overcome before the installed cost of BIPV is competitive with photovoltaic panels.[5] However, there is a growing consensus that through their widespread commercialization, BIPV systems will become the backbone of the zero energy building (ZEB) European target for 2020.[6] Despite the technical promise, social barriers to widespread use have also been identified, such as the conservative culture of the building industry and integration with high-density urban design. These authors suggest enabling long-term use likely depends on effective public policy decisions as much as the technological development.[7]

Forms

The majority of BIPV products use one of two technologies: Crystalline Solar Cells (c-SI) or Thin-Film Solar Cells. C-SI technologies comprise wafers of single-cell crystalline silicon which generally operate at a higher efficiency that Thin-Film cells but are more expensive to produce.[8] The applications of these two technologies can be categorized by five main types of BIPV products:

  1. Standard in-roof systems. These generally take the form of applicable strips of photovoltaic cells.
  2. Semi-transparent systems. These products are typically used in greenhouse or cold-weather applications where solar energy must simultaneously be captured and allowed into the building.
  3. Cladding systems. There are a broad range of these systems; their commonality being their vertical application on a building façade.
  4. Solar Tiles and Shingles. These are the most common BIPV systems as they can easily be swapped out for conventional shingle roof finishes.
  5. Flexible Laminates. Commonly procured in thin-sheet form, these products can be adhered to a variety of forms, primarily roof forms.

With the exception of flexible laminates, each of the above categories can utilize either c-SI or Thin-Film technologies, with Thin-Film technologies only being applicable to flexible laminates – this renders Thin-Film BIPV products ideal for advanced design applications that have a kinetic aspect.

Between the five categories, BIPV products can be applied in a variety of scenarios: pitched roofs, flat roofs, curved roofs, semi-transparent façades, skylights, shading systems, external walls, and curtain walls, with flat roofs and pitched roofs being the most ideal for solar energy capture. The ranges of roofing and shading system BIPV products are most commonly used in residential applications whereas the wall and cladding systems are most commonly used in commercial settings.[9] Overall, roofing BIPV systems currently have more of the market share and are generally more efficient than façade and cladding BIPV systems due to their orientation to the sun.

Building-integrated photovoltaic modules are available in several forms:

Transparent and translucent photovoltaics

Transparent solar panels use a tin oxide coating on the inner surface of the glass panes to conduct current out of the cell. The cell contains titanium oxide that is coated with a photoelectric dye.[22]

Most conventional solar cells use visible and infrared light to generate electricity. In contrast, the innovative new solar cell also uses ultraviolet radiation. Used to replace conventional window glass, or placed over the glass, the installation surface area could be large, leading to potential uses that take advantage of the combined functions of power generation, lighting and temperature control.

Another name for transparent photovoltaics is "translucent photovoltaics" (they transmit half the light that falls on them). Similar to inorganic photovoltaics, organic photovoltaics are also capable of being translucent.

Types of transparent and translucent photovoltaics

Non-wavelength-selective

Some non-wavelength-selective photovoltaics achieve semi-transparency by spatial segmentation of opaque solar cells. This method uses any type of opaque photovoltaic cell and spaces several small cells out on a transparent substrate. Spacing them out in this way reduces power conversion efficiencies dramatically while increasing transmission.[23]

Another branch of non-wavelength-selective photovoltaics utilize visibly absorbing thin-film semi-conductors with small thicknesses or large enough band gaps that allow light to pass through. This results in semi-transparent photovoltaics with a similar direct trade off between efficiency and transmission as spatially segmented opaque solar cells.

Wavelength-selective

Wavelength-selective photovoltaics achieve transparency by utilizing materials that only absorb UV and/or NIR light and were first demonstrated in 2011.[24] Despite their higher transmissions, lower power conversion efficiencies have resulted due to a variety of challenges. These include small exciton diffusion lengths, scaling of transparent electrodes without jeopardizing efficiency, and general lifetime due to the volatility of organic materials used in TPVs in general.

Innovations in transparent and translucent photovoltaics

Early attempts at developing non-wavelength-selective semi-transparent organic photovoltaics using very thin active layers that absorbed in the visible spectrum were only able to achieve efficiencies below 1%.[25] However in 2011, transparent organic photovoltaics that utilized an organic chloroaluminum phthalocyanine (ClAlPc) donor and a fullerene acceptor exhibited absorption in the ultraviolet and near-infrared (NIR) spectrum with efficiencies around 1.3% and visible light transmission of over 65%. In 2017, MIT researchers developed a process to successfully deposit transparent graphene electrodes onto organic solar cells resulting in a 61% transmission of visible light and improved efficiencies ranging from 2.8%-4.1%.[26]

Perovskite solar cells, popular due to their promise as next-generation photovoltaics with efficiencies over 25%, have also shown promise as translucent photovoltaics. In 2015, a semitransparent perovskite solar cell using a methylammonium lead triiodide perovskite and a silver nanowire mesh top electrode demonstrated 79% transmission at an 800 nm wavelength and efficiencies at around 12.7%.[27]

Government subsidies

See also: Financial incentives for photovoltaics.

In some countries, additional incentives, or subsidies, are offered for building-integrated photovoltaics in addition to the existing feed-in tariffs for stand-alone solar systems. Since July 2006 France offered the highest incentive for BIPV, equal to an extra premium of EUR 0.25/kWh paid in addition to the 30 Euro cents for PV systems.[28] [29] [30] These incentives are offered in the form of a rate paid for electricity fed to the grid.

European Union

United States

China

Further to the announcement of a subsidy program for BIPV projects in March 2009 offering RMB20 per watt for BIPV systems and RMB15/watt for rooftop systems, the Chinese government recently unveiled a photovoltaic energy subsidy program "the Golden Sun Demonstration Project". The subsidy program aims at supporting the development of photovoltaic electricity generation ventures and the commercialization of PV technology. The Ministry of Finance, the Ministry of Science and Technology and the National Energy Bureau have jointly announced the details of the program in July 2009.[33] Qualified on-grid photovoltaic electricity generation projects including rooftop, BIPV, and ground mounted systems are entitled to receive a subsidy equal to 50% of the total investment of each project, including associated transmission infrastructure. Qualified off-grid independent projects in remote areas will be eligible for subsidies of up to 70% of the total investment.[34] In mid November, China's finance ministry has selected 294 projects totaling 642 megawatts that come to roughly RMB 20 billion ($3 billion) in costs for its subsidy plan to dramatically boost the country's solar energy production.[35]

Other integrated photovoltaics

Vehicle-integrated photovoltaics (ViPV) are similar for vehicles.[36] Solar cells could be embedded into panels exposed to sunlight such as the hood, roof and possibly the trunk depending on a car's design.[37] [38] [39] [40]

Challenges

Performance

Because BIPV systems generate on-site power and are integrated into the building envelope, the system’s output power and thermal properties are the two primary performance indicators. Conventional BIPV systems have a lower heat dissipation capability than rack-mounted PV, which results in BIPV modules experiencing higher operating temperatures. Higher temperatures may degrade the module's semiconducting material, decreasing the output efficiency and precipitating early failure. In addition, the efficiency of BIPV systems is sensitive to weather conditions, and the use of inappropriate BIPV systems may also reduce their energy output efficiency.[41] In terms of thermal performance, BIPV windows can reduce the cooling load compared to conventional clear glass windows, but may increase the heating load of the building.[42]

Cost

The high upfront investment in BIPV systems is one of the biggest barriers to implementation. In addition to the upfront cost of purchasing BIPV components, the highly integrated nature of BIPV systems increases the complexity of the building design, which in turn leads to increased design and construction costs. Also, insufficient and inexperienced practitioners lead to higher employment costs incurred in the development of BIPV projects.

Policy and regulation

Although many countries have support policies for PV, most do not have additional benefits for BIPV systems. And typically, BIPV systems need to comply with building and PV industry standards, which places higher demands on implementing BIPV systems. In addition, government policies of lower conventional energy prices will lead to lower BIPV system benefits, which is particularly evident in countries where the price of conventional electricity is very low or subsidized by governments, such as in GCC countries.[43]

Public understanding

Studies show that public awareness of BIPV is limited and the cost is generally considered too high. Deepening public understanding of BIPV through various public channels (e.g., policy, community engagement, and demonstration buildings) is likely to be beneficial to its long-term development.

See also

Further reading

External links

Notes and References

  1. Web site: Building Integrated Photovoltaics (BIPV) . Whole Building Design Guide . Strong . Steven . wbdg.org . June 9, 2010 . 2011-07-26.
  2. Web site: Building Integrated Photovoltaics: An emerging market. 6 August 2012. 24 September 2015. https://web.archive.org/web/20150924104611/http://www.solarserver.com/solar-magazine/solar-report/solar-report/building-integrated-photovoltaics-an-emerging-market.html. dead.
  3. Book: Patrina . Eiffert . Gregory J. . Kiss . 2000 . Building-Integrated Photovoltaic Designs for Commercial and Institutional Structures: A Source Book for Architect . 59 . DIANE . 978-1-4289-1804-7 .
  4. Book: Eiffert, Patrina. An Economic Assessment of Building Integrated Photovoltaics. 1998. Oxford Brookes School of Architecture.
  5. James, Ted; Goodrich, A.; Woodhouse, M.; Margolis, R.; Ong, S. (November 2011). "Building-Integrated Photovoltaics (BIPV) in the Residential Sector: An Analysis of Installed Rooftop System Prices." NREL/TR-6A20-53103.
  6. Investigation of building integrated photovoltaics potential in achieving the zero energy building target. 23. 1. 92–106. Angeliki Kylili, Paris A. Fokaides. 10.1177/1420326X13509392. 2014. Kylili. Angeliki. Fokaides. Paris A.. 110970142.
  7. 10.1080/00139157.2014.964092. Building-Integrated Photovoltaics: Distributed Energy Development for Urban Sustainability. Environment: Science and Policy for Sustainable Development. 56. 6. 4–17. 2014. Temby. Owen. Kapsis. Konstantinos. Berton. Harris. Rosenbloom. Daniel. Gibson. Geoffrey. Athienitis. Andreas. Meadowcroft. James. 110745105.
  8. Tripathy . M. . Sadhu . P. K. . Panda . S. K. . 2016-08-01 . A critical review on building integrated photovoltaic products and their applications . Renewable and Sustainable Energy Reviews . en . 61 . 451–465 . 10.1016/j.rser.2016.04.008 . 1364-0321.
  9. Kuhn . Tilmann E. . Erban . Christof . Heinrich . Martin . Eisenlohr . Johannes . Ensslen . Frank . Neuhaus . Dirk Holger . 2021-01-15 . Review of technological design options for building integrated photovoltaics (BIPV) . Energy and Buildings . en . 231 . 110381 . 10.1016/j.enbuild.2020.110381 . 225225301 . 0378-7788. free .
  10. http://miasole.com/products/ MiaSolé website
  11. http://s3-eu-west-1.amazonaws.com/bipvco/wp-content/uploads/2016/11/04124258/BIPVco_PowerPly_LR.pdf BIPVco technical datasheet
  12. https://www.zep.solar/en/home ZEP BV
  13. Book: Eiffert, Patrina . Building-Integrated Photovoltaic Designs for Commercial and Institutional Structures: A Source Book for Architect . 2000 . 60–61.
  14. http://s3-eu-west-1.amazonaws.com/bipvco/wp-content/uploads/2017/07/15164743/BIPVco_Flextron_LR.pdf Technical datasheet for a free-standing flexible module
  15. http://s3-eu-west-1.amazonaws.com/bipvco/wp-content/uploads/2016/10/14170102/BIPVco_Metektron_LR.pdf Technical datasheet for a heat and vacuum-sealed CIGS cell
  16. 10.1016/S1471-0846(08)70179-3 . Henemann . Andreas . David H. Bailey (mathematician) . BIPV: Built- in Solar Energy . Renewable Energy Focus . 9 . 6 . 14, 16–19 . 2008-11-29 .
  17. 10.1016/j.nanoen.2020.105146 . Rim Yeo. Hye. Aesthetic and colorful: Dichroic polymer solar cells using high-performance Fabry-Pérot etalon electrodes with a unique Sb2O3 cavity. Nano Energy. 77 . 6. 2020. 105146. 225502407.
  18. 10.1038/s41598-017-10937-3. Lee. KT. Highly Efficient Colored Perovskite Solar Cells Integrated with Ultrathin Subwavelength Plasmonic Nanoresonators. Scientific Reports. 7 . 2017-09-06. 1. 10640. 28878362. 5587539. 2017NatSR...710640L.
  19. Web site: The Vibrance of Natural Color.
  20. Cerda. Bayron . Natural dyes as sensitizers to increase the efficiency in sensitized solar cells. Journal of Physics . 2016. 720 . 1 . 012030 . 10.1088/1742-6596/720/1/012030 . 2016JPhCS.720a2030C . 99322759 . free .
  21. 10.1155/2013/654953. Kushwaha. Reena . Natural Pigments from Plants Used as Sensitizers for TiO2 Based Dye-Sensitized Solar Cells. Journal of Energy. 2013 . 2013-11-04. 1–8. free.
  22. Transparent PV Panel . West . Mike . Energy Efficiency and Environmental News . November 1992 . October 5, 2011.
  23. Traverse. Christopher J.. Pandey. Richa. Barr. Miles C.. Lunt. Richard R.. 2017-10-23. Emergence of highly transparent photovoltaics for distributed applications. Nature Energy. 2. 11. 849–860. 10.1038/s41560-017-0016-9. 2017NatEn...2..849T. 116518194. 2058-7546.
  24. Lunt. Richard R.. Bulovic. Vladimir. 2011-03-14. Transparent, near-infrared organic photovoltaic solar cells for window and energy-scavenging applications. Applied Physics Letters. 98. 11. 113305. 10.1063/1.3567516. 2011ApPhL..98k3305L. 0003-6951. free. 1721.1/71948. free.
  25. Bailey-Salzman. Rhonda F.. Rand. Barry P.. Forrest. Stephen R.. 2006-06-05. Semitransparent organic photovoltaic cells. Applied Physics Letters. 88. 23. 233502. 10.1063/1.2209176. 2006ApPhL..88w3502B. 0003-6951. 2027.42/87783. free.
  26. Web site: Transparent, flexible solar cells combine organic materials, graphene electrodes. Main. en. 2019-11-27.
  27. Bailie. Colin D.. Christoforo. M. Greyson. Mailoa. Jonathan P.. Bowring. Andrea R.. Unger. Eva L.. Nguyen. William H.. Burschka. Julian. Pellet. Norman. Lee. Jungwoo Z.. Grätzel. Michael. Noufi. Rommel. 2015-03-05. Semi-transparent perovskite solar cells for tandems with silicon and CIGS. Energy & Environmental Science. en. 8. 3. 956–963. 10.1039/C4EE03322A. 1237896. 1754-5706.
  28. Web site: Eugene Standard . Subsidies: France moves up, Netherlands down . https://web.archive.org/web/20061004153158/http://eugenestandard.org/index.cfm?inc=news&id=96 . dead . 2006-10-04 . 30 €ct per kilowatt-hour (40 €ct for Corsica) for twenty years, while an extra premium of 25 €ct/kWh is received for roof-, wall- or window-integrated PV. Moreover, individual households also can receive a 50% tax credit for their PV investments. . 2006 . 2008-10-26 .
  29. Web site: . CLER - Comité de Liaison Energies Renouvelables . 30 à 55* c€/kWh en France continentale . 2008-06-03 . 2008-10-26 . dead . https://web.archive.org/web/20090418024952/http://www.cler.org/info/article.php3?id_article=3281 . 2009-04-18 .
  30. http://www.leonardo-energy.org/drupal/node/897 PV Subsidies: France up, Netherlands down | Leonardo ENERGY
  31. Web site: Feed-in Tariffs.
  32. Web site: DSIRE Home . dsireusa.org . 2011 . October 5, 2011.
  33. Web site: China launches "Golden Sun" subsidies for 500 MW of PV projects by 2012 . SNEC PV . snec.org.cn . 2011 . China launched its much anticipated Golden Sun program of incentives for the deployment of 500 MW of large-scale solar PV projects throughout the country on July 21. . October 5, 2011 . dead . https://web.archive.org/web/20110707050338/http://www.snec.org.cn/Read_e.asp?ID=8582 . July 7, 2011 .
  34. Web site: The Golden Sun of China . https://web.archive.org/web/20100205205504/http://www.pvgroup.org/events/ctr_031358 . dead . February 5, 2010 . PV Group . pvgroup.org . 2011 . October 5, 2011 .
  35. Web site: Here Comes China's $3B, 'Golden Sun' Projects . Ucilia . Wang . Greentech Media . November 16, 2009 . October 5, 2011.
  36. https://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&tp=&arnumber=6844150&openedRefinements%3D*%26filter%3DAND(NOT(4283010803))%26pageNumber%3D9%26rowsPerPage%3D100%26queryText%3D(photovoltaics+) Browse Conference Publications > Ecological Vehicles and Renew ... Help Working with Abstracts Back to Results Vehicle-integrated Photovoltaic (ViPV) systems: Energy production, Diesel Equivalent, Payback Time; an assessment screening for trucks and busses
  37. http://www.renewableenergyworld.com/articles/2005/05/from-bipv-to-vehicle-integrated-photovoltaics-31149.html From BIPV to Vehicle-Integrated Photovoltaics
  38. http://ryanmccarthy.com.au/2009/12/28/opportunities-for-vehicle-integrated-photovoltaics/ Opportunities for Vehicle Integrated Photovoltaics
  39. http://www.idtechex.com/events/presentations/vehicle-integrated-photovoltaics-and-infra-red-harvesting-002406.asp VIPV and infrared harvesting
  40. http://solarvehicles.sphericalstructures.com/ Solar vehicles
  41. Yang . Rebecca Jing . Zou . Patrick X.W. . 2016-01-02 . Building integrated photovoltaics (BIPV): costs, benefits, risks, barriers and improvement strategy . International Journal of Construction Management . 16 . 1 . 39–53 . 10.1080/15623599.2015.1117709 . 112302779 . 1562-3599.
  42. Chen . Liutao . Yang . Jiachuan . Li . Peiyuan . 2022-01-15 . Modelling the effect of BIPV window in the built environment: Uncertainty and sensitivity . Building and Environment . en . 208 . 108605 . 10.1016/j.buildenv.2021.108605 . 244502729 . 0360-1323.
  43. Sharples . Steve . Radhi . Hassan . 2013-07-01 . Assessing the technical and economic performance of building integrated photovoltaics and their value to the GCC society . Renewable Energy . en . 55 . 150–159 . 10.1016/j.renene.2012.11.034 . 0960-1481.