BSI PD IEC/TS 62548:2013:2014 Edition
$198.66
Photovoltaic (PV) arrays. Design requirements
| Published By | Publication Date | Number of Pages |
| BSI | 2014 | 64 |
This Technical Specification sets out design requirements for photovoltaic (PV) arrays including d.c. array wiring, electrical protection devices, switching and earthing provisions. The scope includes all parts of the PV array up to but not including energy storage devices, power conversion equipment or loads.
The object of this Technical Specification is to address the design safety requirements arising from the particular characteristics of photovoltaic systems. Direct current systems, and PV arrays in particular, pose some hazards in addition to those derived from conventional a.c. power systems, including the ability to produce and sustain electrical arcs with currents that are not greater than normal operating currents.
In grid connected systems the safety requirements of this Technical Specification are however critically dependent on the inverters associated with PV arrays complying with the requirements of IEC 62109‑1 and IEC 62109‑2 .
Installation requirements are also critically dependent on compliance with IEC 60364 series (see Clause 4).
PV arrays of less than 100 W and less than 35 V d.c. open circuit voltage at STC are not covered by this Technical Specification.
Attention is drawn to Annex D describing arc fault detection and interruption in PV arrays. It is expected that requirements for the use of this type of equipment will be included in this Technical Specification when reliable commercial equipment for detection of arcs in PV systems is available.
This Technical Specification covers the protection requirements of PV arrays which develop as a result of the use of batteries in PV systems.
Additional requirements may be needed for more specialized installations e.g. concentrating systems, tracking systems or building integrated PV.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 4 | CONTENTS |
| 7 | FOREWORD |
| 9 | 1 Scope and object 2 Normative references |
| 11 | 3 Terms and definitions, symbols and abbreviations 3.1 Terms, definitions and symbols |
| 17 | 3.2 Abbreviations 4 Compliance with IEC 60364 |
| 18 | 5 PV array system configuration 5.1 General 5.1.1 Functional configuration of a PV system 5.1.2 PV system architectures 5.1.3 Array electrical diagrams Figures Figure 1 – General functional configuration of a PV powered system |
| 19 | Figure 2 – PV array diagram – single string case |
| 20 | Figure 3 – PV array diagram – multiple parallel string case |
| 21 | Figure 4 – PV array diagram – multiple parallel string casewith array divided into sub-arrays |
| 22 | Figure 5 – PV array using a PCE with multiple MPPT d.c. inputs |
| 23 | 5.1.4 Use of PCE with multiple d.c. inputs Figure 6 – PV array using a PCE with multiple d.c.inputs internally connected to a common d.c. bus |
| 24 | 5.1.5 Series-parallel configuration 5.1.6 Batteries in systems 5.1.7 Considerations due to prospective fault conditions within a PV array |
| 25 | 5.1.8 Considerations due to operating temperature 5.1.9 Performance issues |
| 26 | 5.2 Mechanical design 5.2.1 General 5.2.2 Thermal aspects 5.2.3 Mechanical loads on PV structures 5.2.4 Wind 5.2.5 Material accumulation on PV array 5.2.6 Corrosion |
| 27 | 6 Safety issues 6.1 General 6.2 Protection against electric shock 6.3 Protection against overcurrent 6.3.1 General 6.3.2 Requirement for overcurrent protection 6.3.3 Overcurrent protection in PV systems connected to batteries |
| 28 | 6.3.4 Requirement for string overcurrent protection 6.3.5 Requirement for sub-array overcurrent protection 6.3.6 Overcurrent protection sizing |
| 29 | Figure 7 – Example of a PV array diagram where strings are grouped under one overcurrent protection device per group |
| 30 | 6.3.7 Overcurrent protection location Tables Table 1 – Nominal overcurrent rating of functional earth fault interrupter |
| 31 | 6.4 Requirements for PV arrays operating at DVC-B and DVC-C voltages 6.4.1 Detection and alarm requirements Table 2 – Requirements for different system types based on PCE isolation and PV array functional earthing |
| 32 | Table 3 – Minimum insulation resistance thresholdsfor detection of failure of insulation to earth |
| 33 | 6.4.2 Earth fault alarm Table 4 – Response time limits for sudden changes in residual current |
| 34 | 6.5 Protection against effects of lightning and overvoltage 6.5.1 General 6.5.2 Protection against overvoltage 7 Selection and erection of electrical equipment 7.1 General |
| 35 | 7.2 PV array maximum voltage 7.3 Component requirements 7.3.1 General Table 5 – Voltage correction factors for crystalline and multi-crystalline silicon PV modules |
| 36 | 7.3.2 PV modules 7.3.3 PV array and PV string combiner boxes 7.3.4 Circuit breakers |
| 37 | 7.3.5 Disconnectors and switch-disconnectors 7.3.6 Cables |
| 38 | Table 6 – Minimum current rating of circuits |
| 40 | 7.3.7 Segregation of a.c. and d.c. circuits 7.3.8 Plugs, sockets and connectors Figure 8 – Reinforced protection of wiring |
| 41 | 7.3.9 Wiring in combiner boxes 7.3.10 Fuses 7.3.11 Bypass diodes 7.3.12 Blocking diodes |
| 42 | 7.4 Location and installation requirements 7.4.1 Disconnecting means |
| 43 | Table 7 – Disconnection device requirements in PV array installations |
| 44 | 7.4.2 Earthing and bonding arrangements |
| 45 | Figure 9 – PV array exposed conductive parts functional earthing/bonding decision tree |
| 46 | Figure 10 – Exposed conductive parts earthing in a PV array |
| 48 | 7.4.3 Wiring system Figure 11 – PV string wiring with minimum loop area |
| 49 | 8 Acceptance 9 Operation/maintenance |
| 50 | 10 Marking and documentation 10.1 Equipment marking 10.2 Requirements for signs 10.3 Identification of a PV installation 10.4 Labelling of PV array and PV string combiner boxes 10.5 Labelling of disconnection devices 10.5.1 General 10.5.2 PV array disconnecting device |
| 51 | 10.6 Documentation |
| 52 | Annex A (informative) Examples of signs Figure A.2 – Example of switchboard sign for identification of PV on a building |
| 53 | Annex B (informative) Examples of system functional earthing configurations in PV arrays Figure B.1 – System functional earthing/grounding |
| 54 | Figure B.2 – Examples different PV configurations in common use |
| 55 | Annex C (informative) Blocking diode |
| 56 | Figure C.1 – Effect of blocking diode at short circuit in PV string Figure C.2 – Effect of blocking diode where there isan earth fault on a system with earthing on the minus side |
| 57 | Figure C.3 – Effect of blocking diode where there isan earth fault on a system with positive side earthing |
| 59 | Annex D (informative) Arc fault detection and interruption in PV arrays Figure D.1 – Examples of types of arcs in PV arrays |
| 61 | Annex E (informative) DVC limits Table E.1 – Summary of the limits of the decisive voltage classes |
| 62 | Bibliography |
