1. A review of the photovoltaic module and panel fire tests ID n. 165
Cancelliere P.1, Manzini G.2, Mazzaro M.3
1Senior Officer Fire Engineer, Italian National Rescue and Services, Central Directorate for Fire Prevention and Technical Safety, Rome, ITALY, (Corresponding Author)
2Senior Researcher, RSE S.p.A., Milano, ITALY
3Chief Fire Engineer, Italian National Rescue and Services, National Fire Investigation Unit NIA, Central Directorate for Fire Prevention and Technical Safety, Rome, ITALY 1

2. Summary and Research’s objectives
In modern buildings the use of photovoltaic (PV) systems is not only related to the solar energy conversion into electrical one, but these systems could also be used as thermal protection building components or aesthetic elements in roofs or facades. Thanks to the environmental policies, a strong development of photovoltaic installations has been growing all over the world. The design and installation of photovoltaic systems involves several problems to be dealt with. In fact, the diffusion of this systems has been accompanied by several cases of accidental fires whose number has been increasing. One of the key fire safety factor of PV systems is the fire behaviour of the module, panels and building substrates. This paper aims to describe and discuss the current fire test methods for PV module and panel fire behaviour characterizations (weaknesses, possible next steps, …).
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 2

3. Summary and Research’s objectives
Introduction
Fire test methods and rating classifications of PV modules
Conclusions
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 3

4. Introduction
PhotoVoltaic (PV) systems could be both a proper ignition source and a suitable fire spread way (cause or victim of a fire).
New challenging fire risk factor on building components such as roofs or facades. According to a recent survey of the Italian National Fire Rescue and Service, around 2500 fire-related accidents have occurred in the nearly 550’000 PV systems currently installed in Italy.
Fig. 1. Italian PV fire related accidents
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 4

5. Introduction
About PV systems on buildings, the Authority having jurisdiction (AHJ) for fire safety in Italy, in 2012 has released a Guideline in order to assess and mitigate the risk of fire when a PV system is put in place on a building as a façade or as a roof.
Other AHJs in European, north Americans and middle east countries have released fire safety guidelines or code standards containing recommendation and technical solution to install PV systems on buildings.
In those documents, the fire behaviours of the PV modules is taken into account, considering also the installation substrates used to put in place and sustain the PV systems.
The aim of this work is summarize the fire risk documents about PV systems on buildings, which are currently used.
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 5

6. Fire test methods and rating classifications of PV modules
International PV Systems Fire Standards
IEC 61730:2016
Table 4 - Fire hazard tests
Test
Title
Referenced standards
Based on
IEC
MST 21
Temperature test
ANSI/UL 1703:2015 -
MST 22
Hot-spot endurance test
MQT 09
MST 23*
Fire Test
National/Local code
MST 24
Ignitability test
 ISO
MST 25
Bypass diode thermal test
MQT 18
MST 26
Reverse current overload test *
Fire tests are locally regulated and topically only required for building integrated or building added products, typically to verify their ability to resist fire from external sources
If at a national level there are no requirements or local fire regulation, the standard (Annex B) list a set of international and national standards which could be used:
ISO Fire-resistance tests - Elements of building construction - Part 1: General requirements;
ISO Fire-resistance tests - Elements of building construction - Part 3: Commentary on test method and guide to the application of the outputs from the fire-resistance test;
ISO 5657:1997 Reaction to fire tests - Ignitability of building products using a radiant heat source;
ISO Fire classification of construction products and building elements. Classification using data from external fire exposure to roofs tests
ENV through 4, Test methods for roof coverings under the influence of a thermal attack of burning brands and radiant heat;
ANSI/UL 790 Standard Test methods for Fire Tests of Roof Coverings;
ANSI/UL 1703:2015, Standard for Flat-plate photovoltaic modules and panels.
Annex B specifies also how to use the different standards in order to characterise a PV module. It highlights that fire behaviour of PV modules installed on or over a building roof or facades is not only related to the flammability characteristic of the module itself but also the combination and configuration of roofing material as well as the mounting system of PV modules play important roles in the fire rating characterisation and PV module classification process.
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 6

7. Fire test methods and rating classifications of PV modules
USA PV Systems Fire Standards
UL 1703:2015 “Standard for Flat-plate photovoltaic modules and panels”
Table 31.2 Required tests for System Fire Class Rating of PV module or panel with mounting system in
combination with roof coverings
At first, this approach ignored the racking assembly’s impact on the spread of flame. As described in the report from Solar America Board for Codes and Standards it is of paramount importance to assess fire exposure of roof assemblies, considering the coupling of both the panel/module and the roof or facade substrate
Table 31.1 Required tests for fire performance of PV modules or panels independent of mounting system and roof covering
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 7

8. Fire test methods and rating classifications of PV modules
USA PV Systems Fire Standards
UL 1703:2015 ”Standard for Flat-plate photovoltaic modules and panels”
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 8

9. Fire test methods and rating classifications of PV modules
European PV Systems Fire Standards
The current European version of the IEC international standard (EN :2007, EN :2007/A1:2012) does not specify a mandatory fire rating procedure, since consensus on this issue has not been reached so far. Fire protection classification is left to national or regional codes. In Europe these regulations are only to be found for roof integrated systems (CEN/TS 1187:2012 “Test methods for external fire exposure to roofs”) and BIPV (EN :2016 “Photovoltaics in buildings - Part 1: BIPV modules”, EN :2016 “Photovoltaics in buildings - Part 2: BIPV systems”).
Europe roof systems - test methods:
a) test 1 – T1 with burning brands;
b) test 2 – T2 with burning brands and wind;
c) test 3 – T3 with burning brands, wind and supplementary radiant heat;
d) test 4 – T4 with two stages incorporating burning brands, wind and supplementary radiant heat.
In addition, within CENELEC the document CLC/TR 50670:2016 “External fire exposure to roofs in combination with Photovoltaic (PV) arrays - Test method(s)” has been recently published (CLC/TC 82 “Solar Photovoltaic energy systems”). It provides some test methods for an initial assessment of fire performance of PV modules on roofs (BIPV - Building Integrated PV, is not covered) without any fire rating criteria.
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 9

10. Fire test methods and rating classifications of PV modules
European PV Systems Fire Standards
Within the CLC TC82 tasks, a research program is currently carrying out by RSE S.p.A., Italian National Fire Rescue and Service, Politecnico di Milano and Istituto Giordano S.p.A. with the main purpose of developing a new step of test protocols about fire behaviour of PV modules on roofs (no BIPV). That program is mainly focused on testing PV module samples taking into account the influence had by: tilting Heat Release Rate (HRR) and size of ignition flame, sample exposure time to ignition flame and presence of sample initial deterioration. Those tests are using the same arrangement of the sample and the burner of the CLC TR within the main European construction products fire behavior facility (i.e. EN "Reaction to fire tests for building products - Building products excluding floorings exposed to the thermal attack by a single burning item”).
They are using some of the same fire ratings variables (e.g. HRR – , FIGRA - FIre Growth RAte, SMOGRA - SMOke Growth RAte, LFS - Lateral Flame Spread, THR - Total Heat Release, TSP - Total Smoke Production, post – combustion time, Flaming droplets, etc.).
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 10

11. Fire test methods and rating classifications of PV modules
Italian PV Systems Fire Standards
The Italian National Fire Rescue and Service has issued a national resolution to test and classifying the reaction to fire of PV modules and panels based on the Decree of the Ministry of the Interior issued on June 26, This technical regulation states that reaction-to-fire performance classifications for combustible materials are determined by using the results from a combination of the three tests listed below:
UNI 9176 “Preparation of the materials to reaction to fire test, D method”;
UNI 8457 “Combustible products which can be hit by flames on one surface - Small flame test”;
UNI 9174 “Reaction to fire of products subjected to a flame in the presence of radiant heat”;
UNI 9177 “Classification of reaction to fire of combustible materials”.
Possible combinations of the roof-top substrate with the fire rate of the PV module installed.
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 11

12. Conclusions
Due to their nature of energy source, fire risk for photovoltaic installations is not negligible and must be correctly evaluated case by case, considering the real position in the building apart from the characteristics of the materials that compose the PV. Fire behaviour of PV modules installed on or over a building roof or facades is not only related to the flammability characteristic of the module itself but also the combination and configuration of roofing material, building substrates as well as the mounting system of PV modules should be taken into account during the fire rating characterisation process. The awareness of the increasing number of PV related fire accidents was vital for the development of modern test methods and classification. What emerges is that more can be done for the harmonisation. A process, which involves various organizations (control Authorities, standardization bodies, modules manufacturers, etc.) for achieving the codification of construction, design and installation of these systems and their components to minimize fire risk should be taken into serious consideration.
Some weaknesses of current testing protocols, mainly due to special design and outside installation features of PV modules: module inclination, ignition flame power and time duration, deterioration of equipment due to environmental conditions, and last but not least the mounting system utilised and coupling with roof.
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 12

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A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 13

14. Thank you for Your kind attention
A review of the photovoltaic module and panel fire tests ID n. 165
Thank you for Your kind attention
Giovanni Manzini
A review of the photovoltaic module and panel fire tests (ID n. 165)
Cancelliere P., Manzini G., Mazzaro M. 14