Issue 99: Fires in Photovoltaic Systems: Lessons Learned from Fire Investigations in Italy
By Luca Fiorentini, Luca Marmo, Enrico Danzi and Vincenzo Puccia
Over the past decade the number of new photovoltaic (PV) system
installations has increased sharply throughout the world. With this
growth, the associated risks grew significantly. This included an
increase in the number of fire incidents involving PV systems. For
example, it is estimated that in Italy alone over 700 fires involving PV
systems occurred in 2012. This has drawn the attention of the fire
safety community and facility managers.
This article will assess some of the fire risks associated with of PV
system installations based on fire investigations conducted in Italy.
The growth of photovoltaic system roof installations has been a result
of public incentives for green energy. Some of the fire incidents
associated with PV systems involved large roof fires and were often
followed by an interior compartment fire. Some of these fires even
resulted in the loss of the structure. The investigations into these
fires revealed that DC arcing and the ignition of combustible roof
insulation, often polyurethane or polystyrene foam, were often
contributing factors in these fires.
The losses that have resulted from these events could have been
reduced by implementing a risk analysis approach in the early design
stages of these installations. This should include evaluating the fire
risk of the most common failures associated with a PV installation, such
as cell mismatch, DC arcing, and localized fires in connection boxes or
At the same time, in Italy there was a short time period for building
owners to access the public incentives. This resulted in compression in
the timing for engineering, procurement, and construction of these
projects, which resulted in the lack of standardization for the specific
PV materials. This along with the inexperience of installers led to an
undervaluation of the fire risk associated the PV system and the
building housing the installation.
Figure 1: A photovoltaic system fire. |
The available data on PV plant fires in Italy includes fire incidents
ranging from fires in an electrical connection, to a limited fire of few
PV modules, to a large fire on the roof of the building spreading
inside through the skylights.
Table 1: Fires related to Photovoltaic Installations, courtesy of Italian National Fire Corp, |
Table 1 refers to the number of incidents related to fires of various
magnitudes that involved, but not necessary started from, PV system
installations in Italy. The analysis of the data shows the number of
fires peaked in 2012 following the first wave of installations. Since
these fires involved new installations, the lack of qualifications of
designers/installers played a role in these fires. This included the
incorrect management of shading, the exposure of plant components to
substandard conditions (heavy water condensation under the panels), low
quality components, crushing of cables during the installation,
under-evaluation of typical DC current behavior, and mismatch of PV
Figure 2: A fire in a connection box in a ground PV system.|
Figure 3: DC arcing effects on an external side of polyurethane.|
Additionally as shown in Table 1, after 2012 the number of fires
involving PV system installations has dropped as the market for
PV-related services decreased. This has led to a better qualified
workforce to install these systems. At the same time, better product
standards and an increase in national regulations have also helped.
Moreover, after the first relevant fires occurred, most PV panels
producers started to include fire resistance requirements in the
Figure 4: A 1000 sq. meter warehouse housing a roof-mounted PV system. |
Figures 5A, 5B and 5C – A fire involving a PV system produced citizen concerns in regards to pollution and public safety.
Figure 6 -- A large warehouse fire strongly influenced in its growth by the PV system.|
Based on this assessment, the following common fire scenarios were observed:
- A building compartment fire spreading through openings and propagating to the roof
- Fire starting in PV modules installed on a roof with fire spreading to the building compartment.
Additionally, PV plant components on a roof or on a building façade could:
- Alter the spread of fire outside or throughout the building.
- Result in combustion products interfering with the smoke and venting systems.
- Be an obstacle to firefighting operations.
- Introduce a safety hazard to firefighters as a result of the presence of energized electrical components.
A preventive fire risk assessment on the PV roof configuration could
easily identify the inherent dangers associated with coupling a strong
fire load with an almost unavoidable ignition source. Also, skylights or
the smoke evacuation systems can be a pathway for internal fire spread.
Based on the results of investigations of fires that occurred in PV
system installation in Italy, there is a need for a comprehensive review
of the fire and building code requirements for PV roof installations.
Specifically, these requirements should address combustible insulating
and roof materials located below active PV system components.
Luca Fiorentini is with Tecsa Srl, Luca Marmo is with Politecnico
di Torino, Enrico Danzi is with Politecnico di Torino, and Vincenzo
Puccia is with National Fire Corps.
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Association of British Insurers (Partially Revised August 2008) May 2003
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 Solar America Board for Codes and Standards (Solar ABCs) Impacts
on Photovoltaic Installations of Changes to the 2012 International Codes
3rd Quarter 2013 – The Application of Fire Risk Assessment in Building Design and Management -- David A. Charters, Ph.D., BRE Global
While for the vast majority of history, fire risks have not been
assessed for the design of buildings, the author explains that
assessment is catching on as a way to avoid the many and varied fatality
fire disasters that have occurred in the past. He explains other
reasons why fire risk assessment is gaining traction as well, and covers
qualitative, semi-quantitative, and quantitative assessment methods. READ MORE
3rd Quarter 2013 -- Fire Protection Inspection, Testing, and Maintenance and Building Fire Risk -- Francisco Joglar, Ph.D., Hughes Associates
This article describes how inspection, testing, and maintenance of
fire protection can be incorporated into a building fire risk model so
that such activities can be managed on a performance-based approach in
specific applications. The author defines "fire risk” for the purpose of
this article as a quantitative measure of the potential for realization
of unwanted fire consequences. He also explains how maintenance issues
factor into the risk equation. READ MORE
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