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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
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
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
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
Questions?Fire consultancy & test: www.bre.co.uk/fire
BRE Renewables Consultancy:www.bre.co.uk/renewablesTel: +44 (0) 1923 664 000
Steve Pester: pesters@bre.co.uk
MCS Installers & Products:www.greenbooklive.com/microgenmicrogeninstallers@bre.co.ukmicrogenproducts@bre.co.ukTel: +44 (0) 845 6181514
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