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Part of the BRE Trust
PV & Fire – Is it safe?
Steve PesterPrincipal Consultant, BRE
BIPV Conference UK 2012
Part of the BRE Trust
BRE Global fire experts: Martin Shipp & Steven Manchester
Warning – some of these slides may be a bit scary!
Many new sustainable technologies have fire safety implications
• Modular construction
• Timber frame
• Structural Insulated Panel Systems
• Engineered joists
• Cladding systems
Any energy-handling device can cause fires
What could go wrong with PV?
PV is simple in concept…
The PV Fire Questions:
– Can PV cause fires?
– Can PV exacerbate hazards during a fire caused by something else?
– Does PV present new risks to fire fighters?
Causes
Arcs – potential to cause fires– Electrical shorts or poor connections can cause very
hot arcs, both inside panels and between conductors– DC arcs do not tend to self-extinguish
Arc fault example
- Early failure in LA
- One week operation
- Did not meet installation standards
- No certification on this system
Other sources of ignition
Component break-downs & inverter fires– Same as any other electrical device – very uncommon– Good quality inverters have built-in safety devices
– Fires caused by PV appear to be rare at present!
Exacerbation of existing fires
Glass – potential to exacerbate existing fires– Glass can fall from PV panels when broken– Restricted access to roof?
Toxic substance release?– Appears to be unfounded 1100 deg. C needed –
unconfined fires normally less than this
New risks to fire fighters
– Fire fighters may not recognise PV system – lots of different types
– Shocks through fire hose jets?– DC electrics cannot be completely switched off on most systems– AC detectors will not detect DC– No official guidance yet in the UK for fire-fighters– Feedback from BRE conference (2011) was that hazards are
manageable with prior knowledge
What is Industry doing to address fire risks?
Safe PV System
2. High Quality Components
1. Safe Design
3. Safe Installation
5. Monitoring & Maintenance
4. Inspection & Testing
Main methods of managing the risks
Industry owned
Independent Quality Mark
Microgeneration Certification Scheme (MCS)
Certification is great step forward (but is not a panacea…)
PV Installer Technical Standard (MIS3002)
– New version about to be released
– Calls up new MCS Installation Guide
– Safety-related features:
– Wind loading calculations
– Cable & component ratings
– When and how to use safety devices
– All installations must comply with:
– BS7671 (Wiring Regs)
– Building Regulations
MCS Product Standards for PV
– PV Modules - MCS 005 specifies test standards:
• Module robustness & electrical standards: IEC 61215 or 61646
• CE marking
• Separate module safety qualification: IEC 61730
New MCS standard for pitched roofs
Pitched Roof Installation Kits - MCS 012 (mandatory 2013)
Building envelope requirements of PV & Solar thermal mounting kits address:
– Wind load tests
– Rain ingress tests
– Fire resistance testing
Test Methods
– ISO
– CEN
– BSI
– ASTM
– NES
– DIN
– AFNOR
– Etc……..
Guidance for fire fighters
– No official guidance yet in the UK for fire-fighters
– Office of the Chief Fire and Rescue Adviser– Fire & Rescue Services actively considering– BRE publication on Fire & Renewables
Fire and Rescue Notification
For roof-mounted systems:
– Signage to alert Fire Services mandatory in new Installer Guide
– Mounted next to the supply isolator in the building
– Discussions on national database and/or local registration by installers
Procurement pointers for designers
Modules
– MCS 005 – build quality & performance
– CE mark – basic electrical safety
– IEC 61730 - Photovoltaic (PV) module safety qualification
– Manufactured in ISO9001 certified facility – consistent products– Also wise to check for the ‘double insulation’ (class II) mark
Inverters (central and string types)
Currently only mandatory standards are:– CE marking
– EMC Directive– Low Voltage Directive
– Connection guidelines & type testing– G83 type testing (small systems)– G59 installation or type tested products
– MCS Installation standard requires:– Matching of input voltage & power ratings
Some other devices may help to reduce risks
– Micro-inverters and DC optimisers
– Local & remote ‘Fire-fighter's’ switches
– Arc fault detection – few products available yet
Inspection, Testing & Documentation
International standard, to be called up in MCS:
– IEC 62446: 2009 Grid connected PV systems –minimum requirements for system documentation, commissioning tests, and inspection
Amongst other things:
– Inspection schedule
– Insulation resistance of the d.c. circuits
– Continuity test of protective earthing
Maintenance
– Low maintenance - no moving parts
– Compliant designs are very safe
– Annual cleaning, electrical test & inspection typical
– Expect at least 30 years service from well designed and installed systems
Getting it into perspective
– UK Stats:
– 300 people per year die in fires (lots of minor injuries)
– 3000 die in trips and falls
– 5000 die from hospital-related infections
– To date, no known deaths caused by PV.
Summary 1
– Any innovation may introduce new risks which need to be managed
– Many of the new eco-technologies have risks to be managed
– Any energy-handling device needs special precautions
– Certification of products and installers contributes to safety
– Some of the concerns may be unfounded; others may need a response – work continues.
Summary 2 - Guidance
– For designers, there are some simple pointers for safe procurement decisions & installation practices
– There is now good technical design and installation guidance for systems <50kW. Following this is the best way to manage the risks
– Code of practice required for larger systems– No formal fire fighters’ guidance in UK yet…
– BRE can help via consultancy, training, testing & certification
If designed & installed correctly, PV is not a big fire risk…
Questions?Fire consultancy & test: www.bre.co.uk/fire
BRE Renewables Consultancy:www.bre.co.uk/renewablesTel: +44 (0) 1923 664 000
Steve Pester: [email protected]
MCS Installers & Products:www.greenbooklive.com/[email protected]@bre.co.ukTel: +44 (0) 845 6181514
