Fire Risks and Safety Standards

Transcription

1 Fire Risks and Safety Standards Florian Reil TÜV Rheinland Group Renewable Energies Cologne, Germany Phone: Florian.Reil@de.tuv.com Workshop BIPV The Increasing Role of Photovoltaics in the Building Sector 27th of May 2009, Milano, Italy 1 05/27/2009

2 Contents Safety Standards for PV Modules International Standards for Building Products Fire Resistance for PV Modules as Roof Covering Material Summary Test Procedures for BIPV PV Module as a Source of Fire Fire Hazard due to Arcing Assessments of Fire Risks Methods for Risk Minimization 2 05/27/2009

3 Distribution of BIPV Systems EU market situation of on-grid PV systems Source: BSW/EPIA /27/2009

4 Safety Standards for PV Modules Safety qualification ing acc. to IEC Preconditioning IEC Ed. 2, IEC Fire Glass breakage High voltage Component s Ground continuity Accessibility Temperature Reverse current overload backsheet Partial discharge junction box Preconditioning IEC Ed. 2, IEC Conduit bending Cut Accessibility Impulse voltage Visual inspection Knock out Tests with relevance for building construction 4 05/27/2009 4

5 Safety Standards for PV Modules Safety qualification ing IEC was published in October 2005: IEC : Photovoltaic (PV) module safety qualification Requirements for construction IEC : Photovoltaic (PV) module safety qualification Requirements for ing IEC combines European Safety Class II requirements and safety requirements from UL /27/2009 5

6 Safety Standards for PV Modules Safety qualification ing acc. to EN Preconditioning IEC Ed. 2, IEC Fire is Fire under consideration Glass breakage High voltage Component s No fire available Ground continuity Accessibility Temperature Reverse current overload backsheet Partial discharge junction box Preconditioning IEC Ed. 2, IEC Conduit bending Cut Accessibility Impulse voltage Visual inspection Knock out Tests with relevance for building construction 6 05/27/2009 6

7 International Standards for Building Products Requirements from the Construction Products Directive Low Voltage Directive (LVD) (systems >75 VDC), EN is sufficient. Construction Products Directive (CPD) shall apply to construction products & the following requirements: Mechanical resistance and stability Safety in case of fire Hygiene, health and environment Safety in use Protection against noise Energy economy and heat retention 7 05/27/2009 7

8 International Standards for Building Products Fire s for construction products Related standards to fire s: ISO 834-1:1999 ISO 834-8:2002 DIN EN ISO UL 790:1997 UL 1703:2002 ENV 1187 EN EN ISO 1182:2002 EN ISO 1716:2002 EN ISO 13823:2002 DIN EN ,-4:2007 NVN 7250:2003 DIN ISO ISO :2003 ISO :2005 ISO ,-2:2002 ISO ,-2:2002 DIN EN ISO 1182:2002 DIN EN ISO 1716:2002 EN 1366:1999 NEN /27/2009 8

9 International Standards for Building Products European procedures for fire behaviour EN ISO :2005 Fire classification of construction products and building elements - Part 5: Classification using data from external fire exposure to roofs s Non-combustibility Ignitability of building products Fire resistance against a single flame and a single burning item Limitation of fire propagation Limitation of fire spread. ENV : Test methods for roof coverings under the influence of a thermal attack of burning brands and radiant heat 9 05/27/2009 9

10 International Standards for Building Products Burning brands used at ENV 1187 Different brands and different radiant sources. Additionally, wind conditions are simulated. Burning brands: T1 (Used in Germany) T2 (Used in Sweden) T3 (Used in France) 10 05/27/

11 Test Procedures for PV Building Products Fire s E.g.: Fire method acc. to ENV Burning brand: wired basket filled with wood wool Source: MPA Stuttgart (Material Testing Institute) 11 05/27/

12 Fire Hazards due to Arcing Experiments and risk estimation Arcing as a source of fire. Media reported on one case in TÜV Rheinland conducted several experiments in order to achieve information on: General appearance of electric arcs Behaviour of arcs in the interconnection circuit of PV modules Electrical arc over an open gas range (air) with copper electrodes (3.5mm Ø)

13 Fire Hazards due to Arcing Potential locations in PV arrays for occurance of electrical arcs In PV systems three different arcs can occur Electrical arcs depend on a gas discharge. High ignition voltage but a low burning voltage. The ignition relies on the distance between the electrodes, combination of voltage and current values, dimensions and temperature of the electrodes

14 Fire Hazards due to Arcing Ignition limit of electric arcs Example of ignition limit conducted with copper electrodes in air. Decreasing of electrodes (copper 3.5mm Ø) until arc ignited.

15 Fire Hazards due to Arcing Potential origin for the ignition of electrical arcs Arcs can be caused by connection failures on module and on system level E.g. defective connections resolved from corrosion or faulty soldering joints. The electrical resistance and temperatures at the faulty junctions rise.

16 Arcing Experiments at PV Modules Electrical arcs at PV module components Connectors were cut at four spots at an electrode distance < 0.05mm Arcing experiments at: Cell-cell connector String connector String terminal inside j-box Cable connector inside j-box

17 Arcing Experiments at PV Modules Observations for risk estimation Connection Cell-Cell Damage is high since long burning electric arcs could occur. Also short flashes. Probability is very low hence both bus bars need to be interrupted, bypass diodes need to be defected. String connector Damage is high since long burning arcs could occur. Two or three connections exist between cell and string connector. Fault soldering (e.g. cold junction) is possible, systematic failure.

18 Arcing Experiments at PV Modules Observations for risk estimation String terminal inside junction box Damage: minor. Electric arc extinguishes very fast depending on construction. Probability is moderate due to very thin connection line. Can break easily. Clamp connection line in junction box Damage is high. Potting material can catch fire and long burning arcs can occur. Moderate probability because of possible corrosion or loose connection. Only one connection.

19 Assessment of Arcing Risks Different interconnects of PV modules Interconnect Probability X Damage = Risk Cell cell Cell string connector String connector - clamp Clamp cable Summary of electrical arc risks of different interconnects: assessment: 1 = very low; 2 = moderate; 3 = high /27/2009

20 Risk Assessment Measures Principle analysis Arc ignition depends on different requirements such as voltage/currentcombination, distance and dimensions of electrodes, temperature etc. High ignition voltage is necessary but low burning voltage. Analysis of the impacts on PV modules Ignition or combustion of materials Ignition or combustion of surrounding materials Dripping of hot or burning material Sparks Displacement of glowing or hot parts

21 System Product Risk minimisation measures 1. As applicable constructive modifications, introduction of new constructive requirements (design, material flammability etc.). 2. Quality assurance measures during production (production line ). 3. Development and introduction of new qualification s (electrical arc s, material flammability). 4. Regular system inspections (check of cable connectivity or usage infrared thermography) 5. Electronical arc detection. 6. As applicable restrictive installation specifications for BIPV applications and/or fire-safe sub-construction.

22 Thank You for Your Attention! 22 05/27/2009