Experimental Study of the Fire Behaviour on Flat Roof Constructions with Multiple Photovoltaic (PV) Panels
Fire experiments were conducted on four mock-up roof constructions with an array of six photovoltaic (PV) panels to study the fire dynamics and flame spread behaviour, so as to better characterise the fire risks of such a system. As it is customary to retrofit PV panels to existing warehouse roofs, where expanded polystyrene (EPS) and polyvinylchloride-based roofing membrane BROOF(t2) is a typical roofing, the experiments were carried out on such installations, but with a mitigation solution on top; 30 mm mineral wool or 40 mm polyisocyanurate (PIR). All mock-ups were 6.0 m long, whereas the width was 2.4 m (Experiments 1 and 2) and 4.8 m (Experiments 3 and 4), respectively. A wood crib was placed under the PV panels and it ignited the roofing membrane after 7 min to 8 min, which in all four experiments resulted in fire spread under all the six PV panels covering an area of 5.1 m × 2.0 m. However, no self-sustained fire was observed beyond the area below the PV array. Within the first hour, the maximum temperatures were measured to respectively 175 °C and 243 °C underneath the two mitigation solutions of PIR insulation and mineral wool, which is more than 100 °C below the piloted ignition temperature for the EPS insulation. However, the EPS was ignited in both experiments with the PIR insulation due to thermal degradation of the protective material after approximately 1 h. These experiments confirm that a small initial fire underneath a PV installation can transform into a hazardous scenario due to the changed fire dynamics associated with adding the PV panels to the existing roof.
KeywordsPhotovoltaic panels Fire experiments Fire dynamics Mitigation
The authors appreciate the experimental assistance received from research assistant Bjørn Skjønning Andersen from Technical University of Denmark and Richard Clemenceau, laboratory intern from ISTIA—École d’igénieurs de l’Université d’Angers (France). A special thank you goes to Kristian Schiang Frank and Jens Peder Jensen from Nordsjællands Brandskole for providing the experimental grounds and for their help with the construction of the mock-ups, the experiments and the extinguishment. The project was partially sponsored by IKEA Services AB.
- 1.Masson G, Kaizuka I, Brunisholz M (2018) 2017 Snapshot of global photovoltaic markets. IEA International Energy Agency. ISBN 978-3-906042-72-5. http://www.iea-pvps.org/fileadmin/dam/public/report/statistics/IEA-PVPS_-_A_Snapshot_of_Global_PV_-_1992-2017.pdf. Accessed 3 Aug 2018.
- 2.SEIA Solar Energy Industries Association (2017) Solar means business 2016—tracking solar adoption by America’s top companies. http://www.seia.org/research-resources/solar-means-business-2016. Accessed 12 April 2018.
- 3.SEIA Solar Energy Industries Association (2017) Solar industry data solar industry growing at record pace. http://www.seia.org/research-resources/solar-industry-data. Accessed 12 April 2018.
- 4.Fiorentini L, Marmo L, Danzi E, Puccia V (2015) Fires in photovoltaic systems: lessons learned from fire investigations in Italy. SFPE Emerging Trends Enewsletter. http://www.sfpe.org/?page=FPE_ET_Issue_99&hhSearchTerms=“issue+and+99. Accessed 21 June 2017.
- 7.Brooks B (2012) The ground-fault protection blind spot: A safety concern for larger photovoltaic systems in the United States. Solar American Board for Codes and Standards. http://www.solarabcs.org/about/publications/reports/blindspot/. Accessed 12 April 2018.
- 9.Wohlgemuth JH, Kurtz SR (2012) How can we make PV panels safer? In: Proceedings of 38th IEEE photovoltaic specific conference, pp 3162–3165. https://doi.org/10.1109/PVSC.2012.6318250
- 10.Grant CC (2010) Fire fighter safety and emergency response for solar power systems. The Fire Protection Research Foundation. https://www.nfpa.org/-/media/Files/News-and-Research/Resources/Research-Foundation/Research-Foundation-reports/For-emergency-responders/RFFirefighterTacticsSolarPowerRevised.ashx?la=en. Accessed 12 April 2018.
- 11.Backstrom B, Tabaddor M (2009) Effect of rack mounted photovoltaic modules on the fire classification rating of roofing assemblies. UL Underwriters Laboratories. http://www.solarabcs.org/current-issues/docs/UL_Report_PV_Roof_Flammability_Experiments_11-30-10.pdf. Accessed 12 April 2018.
- 12.Backstrom B, Sloan D (2012) Effect of rack mounted photovoltaic modules on the fire classification rating of roofing assemblies—phase 2. UL Underwriters’ Laboratories. http://www.solarabcs.org/current-issues/docs/UL_Report_Phase2_1-30-12.pdf. Accessed 12 April 2018.
- 13.Backstrom B, Sloan D. (2012) Report of Experiments of minimum gap and flashing for rack mounted photovoltaic modules—phase 4. UL Underwriters Laboratories. http://www.solarabcs.org/current-issues/docs/UL_Report_Gap_and_Flashing_Exps_3-29-12.pdf. Accessed 12 April 2018.
- 14.Backstrom B, Sloan D (2012) Characterization of photovoltaic materials—critical flux for ignition/propagation phase 3. UL Underwriters Laboratories. http://www.solarabcs.org/current-issues/docs/UL_Report_Critical_Flux_Experiments_1-16-12.pdf. Accessed 12 April 2018.
- 15.Backstrom B, Tabaddor M (2009) Effect of rack mounted photovoltaic modules on the fire classification rating of roofing assemblies—demonstration of mitigation concepts. UL Underwriters Laboratories. http://www.solarabcs.org/current-issues/docs/UL_Report_PV_and_Roof_Flammability_Mitigation_2-10-10.pdf. Accessed 12 April 2018.
- 16.Backstrom B, Sloan D (2012) Considerations of module position on roof deck during spread of flame tests—phase 5. UL Underwriters Laboratories. http://www.solarabcs.org/current-issues/docs/UL_Report_Module_Reposition_Experiments_7-24-12.pdf. Accessed 12 April 2018.
- 17.Backstrom B (2013) Validation of roof configuration 2 experiments project 9. UL Underwriters Laboratories, http://www.solarabcs.org/current-issues/docs/Validation_of_Roof_Configuration_2_Experiments.pdf. Accessed 12 April 2018.
- 20.Backstrom R, Dini D (2012), Firefighter safety and photovoltaic installations research project. Technical report, Under writers Laboratories Inc. https://www.scopus.com/record/display.uri?eid=2-s2.0-84872120047&origin=inward&txGid=127f9641ea664c227649bacf72d6aed3. Accessed 12 June 2018.
- 21.Ramsdal R (2017), Brannsjef mener solceller kompliserte Asko-brannen, Teknisk Ukeblad TU Byg. https://www.tu.no/artikler/brannsjef-mener-solceller-kompliserte-asko-brannen-det-er-sol-grunder-rivende-uenig-i/382843. Accessed 6 Aug 2018.
- 22.Rogers J (2017) Solar panel fire fears after panels ignite in new block with thousands possibly at risk, Express. https://www.express.co.uk/news/uk/826553/Solar-panel-fire-fears-BRE-flats-east-London-Bethnal-Green. Accessed 6 Aug 2018.
- 23.Kristensen JS (2015) Fire risk assessment of solar cell array installations on large buildings: how to protect the building in case of fire? Technical Report, Technical University of Denmark (DTU), Department of Civil Engineering, Kgs. Lyngby, Denmark.Google Scholar
- 26.Zhang X, Tao H, Xu W, Liu X, Li X, Zhang X, Hu L (2017) Flame extension lengths beneath an inclined ceiling induced by rectangular-source fires. Combust Flame 176:349–357. https://doi.org/10.1016/j.combustflame.2016.11.004 CrossRefGoogle Scholar
- 28.McAllister S, Finney M (2013) Effect of crib dimensions on burning rate. In: Bradley D, Makhviladze G, Molkov V, Sunderland P, Tamanini F (eds) Proceedings of the seventh international seminar on fire and explosion hazards (ISFEH7). https://doi.org/10.3850/978-981-07-5936-0_08-02.
- 29.Babrauskas V (2014) Ignition handbook. Fire Science Publishers. ISBN 0-9728111-3-3, p 1069Google Scholar