E1_Local+code+of+practice+on+photovoltatic+installation

LOCAL CODE OF PRACTICE ON PHOTOVOLTAIC

INSTALLATIONSingapore Standard SS CP 5:

1998Amendment No. 1

LOCAL CODE OF PRACTICE ON PHOTOVOLTAIC INSTALLATION

• HANDBOOK FOR PHOTOVOLTAIC (PV) SYSTEMS- SEPT 2007, EMA (available from EMA’s web)

• GREEN handbook-photovoltaic (PV) systems in buildings-1H 2008, BCA (available from BCA’s web)

• CODE OF PRACTICE FOR ELECTRICAL INSTALLATIONS(Singapore Standard SS CP 5: 1998 Amendment No. 1)Add new Section 612 under Part 6 – Special installation or locations :Section 612 Solar photovoltaic (PV) power supply systems --- under Public Comments till 9 Oct 2008

HANDBOOK FOR PHOTOVOLTAIC (PV) SYSTEMS- SEPT 2007, EMA (available from EMA’s web)

• GRID –TIE SYSTEM : BOTH GRID POWER SUPPLY AND PV POWER SUPPLY CONNECT IN PARALLEL TO THE LOAD

• PV systems may be connected to the electrical installation within your (residential or non-residential) premises to generate electricity for your own use. Any excess power may be sold into the wholesale electricity market through the power grid owned bySP PowerAssets (“SPPA”).

• This Handbook gives an overview of the current licensing,marketand technical requirements to ensure safety, reliability and power quality of your electrical installation and of the power grid.


2 Electricity Licensing Requirements

• 2.1 If you generate electricity by means of a PV system with less than 1W generation capacity:

• (a) You are not required to hold a Generation Licence to be authorised to generate electricity from the PV system; and

• (b) It is optional for you to register with the wholesale electricity market, which is called the NEMS (National Electricity Market ofSingapore). You need to register with the NEMS only if you wish to sell and get paid for the electricity you inject into the power grid. However if you are a residential electricity consumer, please refer to section 7.


4 Electrical Safety Requirements

4.1 An electrical installation refers to any electrical wiring, fitting or apparatus used for the conveyance and control of electricity in anypremises. Any PV system connected to the electrical installation isconsidered part of the installation.

4.2 Electrical installations are licensed by EMA to ensure they areoperated and maintained by licensed electrical workers (LEWs), andare safe to use.



Engaging a LEW4.3 You are required to engage a LEW to carry out any electrical work onyour electrical installation. Your appointed LEW will be responsiblefor the design, installation, testing, commissioning and maintenanceof your electrical installation. This includes installing and connectingany PV system to the electrical installation within your premises.

4.4 There are 3 classes of LEWs: Licensed Electrician, LicensedElectrical Technician, and Licensed Electrical Engineer. The variousclasses of LEWs are authorised to design, install, repair, maintain,operate, inspect and test electrical installations according to theconditions stated below:



Engaging a LEW4.3 You are required to engage a LEW to carry out any electrical work

onyour electrical installation. Your appointed LEW will be responsiblefor the design, installation, testing, commissioning and maintenanceof your electrical installation. This includes installing and connectingany PV system to the electrical installation within your premises.



Engaging a LEW

4.4 There are 3 classes of LEWs: Licensed Electrician, LicensedElectrical Technician, and Licensed Electrical Engineer. The variousclasses of LEWs are authorised to design, install, repair, maintain,operate, inspect and test electrical installations according to theconditions stated below:• Electrician Not exceeding 45 kVA 1000V & below• Electrical Technician Not exceeding 150 Kva (Design); not

exceeding500 kVA (Operation) 1000V & below• Electrical Engineer No limit Subject to licence conditions



Engaging a LEW

4.5 The Singapore standard for electrical safety applicable to PVsystems is set out in the Code of Practice for Electrical Installations(Singapore Standard CP5:1998), which is published by SPRINGSingapore. A summary of the relevant electrical safety standards andrequirements are set out in Appendix 2. The LEW whom you appointto install and connect your PV system will be responsible forcompliance with the relevant safety standards and requirements.


5 Connecting to the Power Grid

5.1 If you intend to connect and operate your PV system in parallel to thepower grid, your appointed LEW will have to consult SPPA’s agent,SP PowerGrid (“SPPG”) on the connection scheme and the technicalrequirements.5.2 A summary of the consultation process to connect your PV system tothe power grid, is given in Appendix 3. The following documents setout the detailed consultation process and technical requirements:(a) the Transmission Code and the Metering Code, which arepublished at the following EMA websites:http://www.ema.gov.sg/doc/transmission_code.pdfhttp://www.ema.gov.sg/doc/metering_code.pdf(b) SPPG’s handbook entitled “How to Apply for ElectricityConnection”, which is published at the following SPPA website:http://www.sppowerassets.com.sg/PDF/howtoapply.pdf


6 Buildings & Construction Safety6.1 There may be safety standards and

requirements for buildings andconstruction applicable to the

implementation of your PV system.


7 Further Information for Residential PV Systems

7.1 For electrical safety reasons, a residential electricity consumer is required to have his PV system installed and connected to his electrical installation by an LEW (see section 4.6 on search for LEWs). However, the residential consumer is not required to hold an Electrical Installation Licence to use or operate his electrical installation with the PV system connected.


7 Further Information for Residential PV Systems7.2 The residential consumer will have to apply to SP Services (“SPS”)by following the application procedure set out in Appendix 3. If theresidential consumer will export electricity into the power grid andwants to get compensated for the electricity exported, SPS will makearrangements for the compensation by way of a credit adjustment inthe monthly electricity bill to the residential consumer. The creditadjustment will effectively compensate the residential consumer forthe amount of electricity he exports into the power grid during thatmonth based on the prevailing low-tension electricity tariff rate lessthe grid charge. (Note: This scheme to compensate residentialelectricity consumers for the electricity they export into the power gridis not applicable to those residential consumers whose electricityconsumption is metered under the master-sub metering scheme.)* *


Appendix 2: Electrical Safety Standards and RequirementsApplicable to PV Systems

1 A solar photovoltaic power supply system (“PV system”) installedwithin a premises forms part of the consumer’s electrical installation andshall comply with the requirements stipulated in the Electricity Act (cap.89A), the Electricity (Electrical Installations) Regulations, and theSingapore Standard Code of Practice CP5: 1998 for Electrical Installations.

2 Reference shall also be made to IEC 60364-7-712 or BS 7671 forthe technical terms and additional guides for PV systems. These shall beread in conjunction with the following parts of CP5:Part 3: Assessment of general characteristicsPart 4: Protection for safetyPart 5: Selection and erection of equipment


Appendix 2: Electrical Safety Standards and RequirementsApplicable to PV Systems3 Special attention shall be paid to the following:2(a) The protective measures for automatic disconnection ofsupply as stipulated in Part 4 shall be complied with. Theprotective measures of non-conducting location (clause 413-04) and earth-free local equipment bonding (clause 413-05)are not permitted on the d.c. side of the PV system;(b) PV modules shall comply with the requirements of therelevant equipment standards, for example IEC 61215 forcrystalline PV modules. Other accessories such as PV arrayjunction box, PV generator junction box and switchgearassemblies shall comply with the requirements of IEC60439-1;(c) Protection by use of Class II or equivalent insulation shallpreferably be adopted on the d.c. side of the PV system;


Appendix 2: Electrical Safety Standards and RequirementsApplicable to PV Systems3 Special attention shall be paid to the following:(d) The PV equipment shall be arranged so as to facilitate itsoperation, inspection and maintenance and access to eachconnection (clause 513-01-01L). The provisions made bythe manufacturer of the PV equipment for safe maintenanceand service work shall not to be affected;(e) Single-core sheathed cables shall be used for d.c. wiring tominimize the risk of earth faults and short circuits;(f) Means of isolation for the PV system shall comply withclause 537-02. To allow maintenance of the PV inverter,means of isolating the PV inverter from the d.c. side and thea.c. side shall be provided;(g) All junction boxes shall carry a warning label indicating thatthe parts inside the boxes may still be live after isolationfrom the PV inverter (see IEC 712.537.2.5.1);


Appendix 2: Electrical Safety Standards and RequirementsApplicable to PV Systems3 Special attention shall be paid to the following:(h) For a PV system operating in parallel with the power grid,the power grid supply shall be considered the source, andthe electrical installation with the PV system connected shallbe considered the load. The PV inverters shall beconfigured to:• protect the a.c. side of the PV inverter from beingconnected out-of-synchronism with the power gridsupply; and• automatically disconnect the PV supply upon loss ofsupply from the power grid;• automatically disconnect the PV supply when thedirect current injection into the power grid by the PVsystem exceeds 20 mA. An isolating transformer ispreferably installed on the a.c. side of the PV inverterto eliminate the possibility of PV system injectingdirect current into the power grid;


Appendix 2: Electrical Safety Standards and RequirementsApplicable to PV Systems3 Special attention shall be paid to the following:(i) Appropriate protection facilities shall be provided in the PVsystem to:• disconnect the PV system from power grid supply inthe event of fault occurring in the PV system;• avoid danger to the PV system caused by transientabnormalities of the power grid supply such as voltageand frequency fluctuation, voltage dip, etc;


Appendix 2: Electrical Safety Standards and Requirements

Applicable to PV Systems3 Special attention shall be paid to the following:(j) The PV system supply cable on the a.c. side shall beprotected against short-circuit current by an overcurrentprotective device installed at the connection to the a.c.supply (see diagram below); and(k) It is the responsibility of the consumers to have their PVsystems maintained regularly to ensure the safe operationof their PV systems and electrical installations.


Appendix 3: Consultation Process to Install and Connect PV Systems to the Power Grid

PV system owner to engage a Licensed Electrical Worker (LEW) totake charge of installing and connecting the PV system to the grid

Appointed LEW to submit Application Form to SP Services (SPS)

SP PowerGrid (SPPG) to evaluate and discuss withLEW on the technical requirements, and on the technicalspecifications of the PV system to be submitted

Comply with technicalrequirements?

SPPG to advise connection scheme

LEW to install, test and commission PV system andinform both SPPG and SPS

GREEN handbook-photovoltaic (PV) systems in buildings-1H 2008, BCA (available from BCA’s web)

With the formation of the Clean Energy Programme Office, a whole of governmenteffort to develop capability in clean energy, the Building and Construction Authority(BCA) took the initiative to prepare this document as a handbook to complementEMA’s Handbook for Photovoltaic Systems. As this is a relatively new area in Singapore,the document will be updated as and when there is new development.

The aim of this guide is to share and provide the industry and homeowners theprocedures and the good practices in the design, planning and implementation of aphotovoltaic system in a building development.

This guide also provides examples of how photovoltaic (PV) are successfully integratedinto buildings overseas, illustrating how BIPV can both be an energy generator aswell as a versatile building material for the envelope.


1 Introduction1.1 Photovoltaic (PV in short) is a form of clean renewable energy. Most PV

modules use crystalline silicon solar cells, made of semiconductor materials similar to those used in computer chips. Thin film modules use other types of semiconductor materials to generate electricity. When sunlight is absorbed by these materials, the semi-conductor material in the PV cells is stimulated by the photons of the sunlight to generate direct electrical current (DC). They will work as long as they are exposed to daylight. The electricity generated is either used immediately or is stored (eg. in batteries) for future use. Solar modules themselves do not store electricity.

1.2 The objective of this handbook is to provide developers, architects, other professionals as well as interested homeowners with some basic information on how to approach, plan and implement a photovoltaic system to generate electric power in a building development.


2 Design and Installation2.1 Types of Photovoltaic SystemPhotovoltaic systems can be classified based on the end-use

application of the technology. There are two main types of PV systems; grid-tie system and off-grid system.

Grid-Tie System2.1.1 In a grid-tie system (Figure 1), the output of the PV systems is

connected in parallel with the utility power grid. In this way, the power supply drawn from the utility grid will be correspondinglyreduced by the amount of power generated by the PV system. On the other hand when there is little or no output from the PV system due to cloudy weather or at night, the electricity drawn from the utility grid will be correspondingly increased. Hence there is no need to have storage batteries.


2 Design and Installation2.1 Types of Photovoltaic SystemOff-Grid System

2.1.2 In an off-grid system (Figure 2), batteries for energy storage are required to provide electricity under conditions when there is little or no output from the PV system. Currently, such PV systems are already competitive in isolated sites where the electricity grid is far away. Off-grid systems usually power DC loads, such as telecoms systems, rural lighting systems, parking sign lights, lightings in parks etc.

If required, off-grid systems can also include an inverter to drive AC loads.


2 Design and Installation

2.2 EMA’s requirements

Being electrical power systems, PV installations must meet EMA’s requirements. The Energy MarketAuthority(EMA) has published on its website, a Handbook for PV Systems to cover the electrical aspects of PV systems. The Handbook provides information on the licensing, market and technical requirements to ensure safety, reliability and power quality of consumers’electrical installations and of the power grid.


2 Design and Installation

2.3 Where PVs can be installed in a building

There are many ways to install PV systems in a building. For existing buildings, the most commonmanner without drastically affecting its appearance is to mount the PV modules on a frame onthe roof top. Typically, they are mounted above and parallel to the roof surface with a standoff ofseveral centimetres (recommended 10 cm) to reduce module temperature through air circulation.Ideally, they should also be installed facing north-south orientation to maximise the amount of solarenergy received. Singapore’s proximity to the Equator means the module’s compass orientation isnot critical. Laying the modules flat will maximise exposure to the sun. As flat-mounted modules mayget dirty from trapped rain water and dust, it is better to mount the modules at an angle (10-15 forframed modules, or as little as 3-5º for unframed modules) to allow rain water to run off properly. The PV modules should be free of shade. Shading of any cell of a module may reduce the output of the entire module drastically. Therefore,shadows cast by tall trees and neighbouring buildings (including those to be built in future) should be avoided.


In a new development, besides mounting on the roof top, the PV modules or panels could in a creative,aesthetically-pleasing manner be integrated into the building facade (this form of PV is commonly knownas Building Integrated Photovoltaic or BIPV in short). This could be on any part of the roof or external wallsthat is well-exposed to sunlight e.g. skylights, claddings, windows, external shading devices. It could alsobe integrated into external structures such as canopies, car park shelters and railings.


2.4 URA’s requirements on development planning control

At present, there are no specifi c requirements or controls by URA (Urban Redevelopment Authority)on the use of materials such as PVs. However, conservation projects or projects within the CentralArea are subject to URA’s Urban Design evaluation process.Guidelines on Conservation and Development Control

2.4.1 Architects are advised to refer to URA’s guidelines on conservation, urban design and developmentcontrol. The guidelines are available at the URA website.


2.5 BCA’s requirements on structural safety and lightning protectionStructural Safety2.5.1 For new building developments, the design for the structure must take into consideration the loading of the PV installations, just like any other equipment mounted on the building structure.2.5.2 For existing buildings, the service of a professional structural engineer may be required to carry out an inspection of the roof structure and do a calculation on the structural loading. This could be through the PV contractor (System integrator or SI in short) or directly by the building owner. If the roofis unable to withstand the loading of the PV system, there will be a need for structural plans to be submitted to BCA for approval. The application guideline is available at the following BCA website:http://www.bca.gov.sg/StructuralPlan/structural_plan_application.html


2.5 BCA’s requirements on structural safety and lightning protection

Structural Safety

2.5.3 If BIPV glass is used as a glazing material and not as an add-on to existing facade, it will be treated like any other glazing material. No special approval for the use of BIPV will be needed. If BIPV is installed on an existing facade as an add-on, the design for the mounting system must comply with building and structural design code.

The structural loading requirement is as follows:(a) For non-accessible roof, the loading must be below 0.5 kN/m2.(b) For accessible roof, the loading must be below 1.25 kN/m2.


2.5 BCA’s requirements on structural safety and lightning protection

Lightning Protection

2.5.4 Given its location, PV systems are likely to be hit when lightning strikes in the vicinity. As lightning surges in the PVsystem can cause damages to the PV modules and inverters, care must be taken to ensure that proper lightning protection is provided for the system and entire structure. The inverters should be protected by appropriately rated surge arrestors on the DC side. Structures and module frames must be properly grounded.


2.6 Guide For Owners - Installation Of Solar Panels or Photovoltaic (PV)

Owner can check with URA directly whether PV can beinstalled on the building’s facade/roof or Owner can alsoapproach a System Integrator (SI)* for such advice

Owner to appoint SI to take full responsibility of the work.SI to engage professional engineer to assess the condition of building structure and loading of PV.

Owner/SI to appoint a Licensed Electrical Worker (LEW)to be responsible for the electrical works associatedwith the PV system



Appointed LEW to submit Application Form to SP Services(SPS)

SP PowerGrid (SPPG) to evaluate and discuss with LEW onthe technical requirements, and on the technical specifications of the PV system to be submitted

SPPG to advise connection scheme

LEW to carry out or supervise the electrical works associatedwith the PV System (including connection to the powergrid and/or electrical installation), and inform bothSPPG and SPS when completed.



SI:i) should provide an operation and maintenance manualincluding any authority approval (if applicable)handover to homeownerii) should provide a warranty of 12 months of defects liability period

System Integrator (SI) in PV industry refers to a person or company that provides design, supply, delivery,installation, commissioning and maintenance of a photovoltaic power system.


2.7 Design and Installation Checklists

1 Select a location, check with URA whether PV can be installed inbuilding’s facade/roof and set your budget2 Determine energy requirement and estimate of system size3 Site survey for space needed and access for maintenance



4 Engage a licensed electrical worker(LEW) if your proposed PV system:i) is to be connected to the electrical installation within your premises; and/orii) is to be connected and operated in parallel to the power gridThe appointed LEW will be responsible for the design and implementation of the connection of your PV system to the electrical installation and/or power grid5 Selection of module, type and mounting method


2.7 Design and Installation Checklists6 Inverter selection to match PV array• No. of inverters needed• Select inverter type• Location of inverters (accessible for inspection and maintenance)7 Finalise the mounting system8 Ensure there are fi xing and mounting points available



9 Ensure the structure for mounting is safe• Additional loading by PV system is considered• Wind loading is considered• Waterproofi ng is not compromised during installation10 Solar access• Ensure location mounted will get maximum sunlight• Choose a location that is unshaded



11 Modules are installed at optimum orientation (North-south)12 Modules are mounted at a tilt angle (10 to 15 degrees for framedmodules, oras low as 3-5ºfor unframed laminates) for self-cleaning13 Suffi cient ventilation space behind array for cooling purposes



14 Cables used must meet sufficient current-carrying capacity and are suitably rated for the environment usage. DC cables must be single-core, double-insulated. Cable insulation on outdoor cables must withstand high temperatures and UV exposure for 20+ years. PVC and XLPE cables are inadequate and must not be exposed to the elements. (Cable design must comply with CP5)15 Determine if lightning Protection System is needed (Design must comply with CP16 and CP33)16 Ensure that the PV module frame is earthed



17 Finalising the Inverter and AC wiring system18 During installation•PV system should be installed by qualifi ed/experienced system installers•safety rules must be observed, installer must wear PPE•only proper certifi ed safety equipment can be used e.g. scaffolding, stepladders etc.19 Cables must be properly connected, secured and routed



20 Ensure continuity and insulation tests are done21 Completion of testing & system commissioning22 System, documentation/manual handover to owners


3 Operation & Maintenance

3.1 As there are usually no moving parts in PV installations, minimal maintenance is needed. However,routine maintenance is required to ensure that the system is performing properly. It is a goodpractice for PV contractor (or System Integrator) to provide an Operation & Maintenance manualto the owner. The manual should include basic system data, test & commissioning data, O&M dataand warranty information.3.2 The PV modules require routine visual inspection for signs of damage, dirt build-up or shadeencroachment. Although it is usually designed and installed to be self-cleaning through rainwater,the modules should be hosed down if there is a build-up of dust. It is not uncommon for PVperformance to improve slightly the next day after rain.3.3 Periodically, system fixtures must be checked for corrosion. This is



3.1 As there are usually no moving parts in PV installations, minimal maintenance is needed. However, routine maintenance is required to ensure that the system is performing properly. It is a good practice for PV contractor (or System Integrator) to provide an Operation & aintenance manual to the owner. The manual should include basic system data, test & commissioning data, O&M data and warranty information.3.2 The PV modules require routine visual inspection for signs of damage, dirt build-up or shade encroachment. Although it is usually designed and installed to be self-cleaning through rainwater,the modules should be hosed down if there is a build-up of dust. It is not uncommon for PV performance to improve slightly the next day after rain.



3.3 Periodically, system fixtures must be checked for corrosion. This is to ensure the PV system is safely secured.3.4 Any PV system connected to the electrical installation of a building, is considered part of the electrical installation. The licensed electrical worker (LEW) appointed by the building owner is responsible for maintaining the electrical installation to ensure electrical safety.

Recommended Preventive Maintenance Works for Photovoltaic System3.5 Preventive maintenance works should be carried out every six (6) months.3.6 The following table indicates the components/equipments and the corresponding remedial actions to be carried out during the preventive maintenance works.


Recommended Preventive Maintenance Works for Photovoltaic System

1.PhotovoltaicModules

1. Dust/debris on surface.2. Ensure no physical damage on surface.3. Check for loose wire connection.4. Check for wiring conditions.Remedy/Action1. Wipe clean. Do not use any solvents other than water!2. Recommend replacement.3. Retighten connection.4. Replace wiring when necessary.



2. Inverter

1. Check functionality.2. Check for loose wiring connection.3. Check for abnormal operating temperature.

Remedy/Action

1. Recommend replacement.2. Retighten connection.3. Recommended replacement.



3. Lightning / Surge Voltage Protection

1. Check for loose wiring connection.2. Check for all wiring conditions.3. Check fuses, blocking diodes, circuit breakers, surge arrestors.4. Check functionality.

Remedy/Action

1. Retighten connection.2. Replace wiring when necessary.3. Replace when necessary. Ensure to use dc-rated components on the dc side!4. Replace when necessary.


Recommended Preventive Maintenance Works for Photovoltaic SystemRemedy/Action4. Cabling / Junction Box

1. Visually check for wear and tear.2. Check for loose connections.

Remedy/Action1. Replace when necessary.2. Retighten connection.

LOCAL CODE OF PRACTICE ON PHOTOVOLTAIC

INSTALLATIONSingapore Standard SS CP 5:

1998Amendment No. 1

CODE OF PRACTICE FOR ELECTRICAL INSTALLATIONS

Singapore Standard SS CP 5: 1998

Amendment No. 1

, Contents

a) Add new Section 612 under Part 6 –Special installation or locations Section 612 Solar photovoltaic (PV) power supply systems

b) Add new Appendix 7 Harmonized cable core colours under Appendices.

, Part 2 Definitions

a) Amend the introduction of Definitions as follows:

For the purpose of this part of section, the following definitions shall apply. As far as practicable the definitions align with the International Electrotechnical Vocabulary IEC 60050(826) and BS 4727 – ‘Glossary of electrotechnical, power, telecommunication, electronics, lighting and colour terms’.


b) Amend definition of “Neutral conductor”(page 19) as follows:Neutral conductor. A conductor connected to the neutral point of a system and contributing to the transmission of electrical energy. The term also means the equivalent conductor of a d.c. system unless otherwise specified in the Code and also identifies either the mid-wire of a three-wire d.c. circuit or the earthed conductor of a two-wire earthed d.c. circuit.


c) Add the following definitionsPV cellBasic PV device which can generate electricity when exposed to light such as solar radiation

PV moduleSmallest completely environmentally protected assembly of interconnected PV cells


PV stringCircuit in which PV modules are connected in series, in order for a PV array to generate the required output voltage

PV arrayMechanically and electrically integrated assembly of PV modules, and other necessary components, to form a DC power supply unit


PV array junction boxEnclosure where all PV strings of any PV array are electrically connected and where devices can be located

PV generatorAssembly of PV arrays


PV generator junction boxEnclosure where all PV arrays are electrically connected and where devices can be located if necessary

PV string cableCable connecting PV modules to form a PV string


PV array cableOutput cable of a PV array

PV d.c. main cableCable connecting the PV generator junction box to the d.c. terminals of the PV invertor


PV invertorDevice which converts d.c. voltage and d.c. current into a.c. voltage and a.c. current

PV supply cableCable connecting the a.c. terminals of the PV invertor to a distribution circuit of the electrical installation


PV a.c. moduleIntegrated module / invertor assembly where the electrical interface terminals are a.c. only. No access is provided to the d.c. side

PV installationErected equipment of a PV power supply system


Standard test conditions (STC)Test conditions specified in IEC 60904-3 for PV cells and PV modules

Open-circuit voltage under standard test conditions UOC STCVoltage under standard test conditions across an unloaded (open) generator or on the d.c. side of the invertor


Short-circuit current under standard test conditions lSC STCShort-circuit current of a PV module, PV string, PV array or PV generator under standard test conditions

d.c. sidePart of a PV installation from a PV cell to the d.c terminals of the PV invertor


a.c. sidePart of a PV installation from the a.c. terminals of the PV invertor to the point of connection of the PV supply cable to the electrical installation

Simple separationSeparation between circuits or between a circuit and earth by means of basic insulation

SECTION 612(L)SOLAR PHOTOVOLTAIC (PV) POWER

SUPPLY SYSTEMS612.1 Scope

The particular requirements of this section apply to the electrical installations of PV power supply systems including systems with a.c. modules. NOTE 1 – Requirements for PV power supply systems which are intended for stand-alone operation are under consideration.NOTE 2 – (See also Figures 612.1 and 612.2).

612.3 Assessment of generalcharacteristics

612.31 Purpose, supplies and structure


SUPPLY SYSTEMS612.312 Types of distribution systems612.312.2 Types of system earthing

Earthing of one of the live conductors of the d.c side is permitted, if there is at least simple separation between the a.c side and the d.c side.NOTE – Any connections with earth on the d.c. side should be electrically connected so as to avoid corrosion.

612.4 Protection for safety612.41 Protection against electric shock


SUPPLY SYSTEMS612.410.3 General requirements

PV equipment on the d.c side shall be considered to be energized, even when the system is disconnected from the a.c side.

612.410.3.6 The protective measures of non-conduction locations (Clause 413-04) and earth-free local equipotentialbonding (Clause 413-05) are not permitted on the d.cside.


SUPPLY SYSTEMS612.411 Protection measure:

Automatic disconnection of supplyNOTE – Protection by automatic disconnection of supply on the d.c. side requires special measures which are under consideration.

612.411.3.2.1.1On the a.c side, the PV supply cable shall be connected to the supply side of the protective device for automatic disconnection of circuits supplying current-using equipment.


SUPPLY SYSTEMS612.411.3.2.1.2

Where an electrical installation includes a PV power supply system without at least simple separation between the a.c side and the d.c side, an RCD installed to provide fault protection by automatic disconnection of supply shall be type B according to IEC 60755, amendment 2.

Where the PV invertor by construction is not able to feed d.c fault currents into the electrical installation, an RCD of type B according to IEC 60755 amendment 2 is not required.


SUPPLY SYSTEMS612.412 Protection measure: Double or

reinforced insulationProtection of class II or equivalent insulation shall preferably be adopted on the d.c. side.

612.414 Protection Measure: Extra-low voltage provided SELV or PELV

612.414.1 General 612.414.1.1

For SELV and PELV systems, Uoc STC replaces Uoand shall not exceed 120 V d.c


SUPPLY SYSTEMS612.433 Protection against overload on the

d.c side 612.433.1

Overload protection may be omitted to PV string and PV array cables when the continuous current-carrying capacity of the cable is equal to or greater than 1,25 times ISC STC at any location.


SUPPLY SYSTEMS612.433.2

Overload protection may be omitted to the PV main cable if the continuous current carrying capacity is equal to or greater than 1,25 times ISC STC of the PV generator.

NOTE – The requirements of 612.433.1 and 612.433.2 are only relevant for protection of the cables. See as well the manufacturer's instructions for protection of PV modules.


SUPPLY SYSTEMS612.434 Protection against fault currents612.434.1

The PV supply cable on the a.c side shall be protected against fault current by an overcurrent protective device installed at the connection to the a.c mains.

612.444 Protection against electromagnetic interference (EMI) in buildings

612.444.4.4To minimize voltages induced by lightning, the area of all wiring loops shall be as small as possible.


SUPPLY SYSTEMS612.5 Selection and erection of electrical

equipment612.51 Common rules612.511 Compliance with standards



PV modules shall comply with the requirements of the relevant equipment standard, e.g. IEC 61215 for crystalline PV modules. PV modules of class II construction or with equivalent insulation are recommended if UOC STC of the PV strings exceeds 120 V d.c.

The PV array junction box, PV generator junction box and switchgear assemblies shall be in compliance with IEC 60439-1.


SUPPLY SYSTEMS612.512 Operational conditions and external

influences612.512.1.1

Electrical equipment on the d.c side shall be suitable for direct voltage and direct current.

PV modules may be connected in series up to the maximum allowed operating voltage of the PV modules and (UOC STC of the PV strings) and the PV invertor, whichever is lower. Specifications for this equipment shall be obtained from the equipment manufacturer.


SUPPLY SYSTEMS612.512.1.1 (con’td)

If blocking diodes are used, their reverse voltage shall be rated for 2 x UOC STC of the PV string. The blocking diodes shall be connected in series with the PV strings.

612.512.2.1As specified by the manufacturer, the PV modules shall be installed in such a way that there is adequate heat dissipation under conditions of maximum solar radiation for the site.


SUPPLY SYSTEMS612.513 Accessibility612.513.1

The selection and erection of equipment shall facilitate safe maintenance and shall not adversely affect provisions made by the manufacturer of the PV equipment to enable maintenance or service work to be carried out safely.

612.52 Selection and erection of wiring systems

612.522 Selection and erection in relation to external influences


SUPPLY SYSTEMS612.522.8.1

PV string cables, PV array cables and PV DC main cables shall be selected and erected so as to minimize the risk of earth faults and short-circuits.NOTE – This may be achieved for example by reinforcing the protection of the wiring against external influences by the use of single-core sheathed cables.

612.522.8.3Wiring systems shall withstand the expected external influences such as wind, ice formation, temperature and solar radiation.


SUPPLY SYSTEMS612.53 Isolation, switching and control 612.537 Isolation and switching612.537.2 Isolation612.537.2.1.1

To allow maintenance of the PV invertor, means of isolating the PV invertor from the DC side and the AC side shall be provided.NOTE – Further requirements with regard to the isolation of a PV installation operating in parallel with the public supply system are given in Clause 612.55


SUPPLY SYSTEMS612.537.2.2 Devices for isolation612.537.2.2.1

In the selection and erection of devices for isolation and switching to be installed between the PV installation and the public supply, the public supply shall be considered the source and the PV installation shall be considered the load.

612.537.2.2.5A switch disconnector shall be provided on the DC side of the PV invertor.


SUPPLY SYSTEMS612.537.2.2.5.1

All junction boxes (PV generator and PV array boxes) shall carry a warning label indicating that active parts inside the boxes may still be live after isolation from the PV invertor.

612.54 Earthing arrangements, protective conductors and protective bonding conductors

Where protective equipotential bonding conductors are installed, they shall be parallel to and in close contact as possible with DC cables and AC cables and accessories.


SUPPLY SYSTEMS612.55 Additional requirements for PV

installations operating in parallel with public supply system

612.55.1Care shall be taken to avoid adverse effects to the public supply system and to other installations in respect of power factor, voltage changes, harmonic distortion, unbalance, starting, synchronizing or voltage fluctuation effects. The owner of public supply system shall be consulted in respect of particular requirements.



Protection shall be provided to automatically disconnect the PV power supply system from the public supply system in the event of loss of that supply or deviation of the voltage or frequency at the supply terminals from values declared for normal supply.

612.55.3Means shall be provided to prevent the connection of a PV power supply system to the public supply system if the voltage and frequency of the public supply system are outside the limits of operation of the protection required by Clause 612.55.2.



Means shall be provided to enable the PV power supply system to be isolated from the public supply system. Warning notices for dual supply source shall be affixed at the following locations in the installation i) At the origin of the installation;ii) At the meter position, if remote from the origin;iii) At the consumer unit or distribution board to which

the PV power supply system is connectediv) At all points of isolation of both sources of supply


SUPPLY SYSTEMSThe warning notice shall have the following wording:

WARNING – DUAL SUPPLY

Isolate both mains and on-site PV power supply system before carrying out work.

Isolate the mains supply at ….…………………………………

Isolate the PV power supply system at ………………………


SUPPLY SYSTEMS


SUPPLY SYSTEMSPage 179, Appendix 1(L)

Amend the relevant references in Appendix 1(L) as follows:a) Delete the follow standards:

BS 1710 : 1984 (1991)

Specification for identification of pipelines and services.

514-02-01

IEC 73: 1991 Coding of indicating devices and actuators by colours and supplementary means.



b) Amend the following references:

BS 3858 : 1992 Specification for binding and identification sleeves for use on electric cables and wires

514-03-02



c) Add the following references:

IEC 60050(826) : 1982

International ElectrotechnicalVocabulary (IEV) –Chapter 826 : Electrical installations of buildings

Part 2 Definitions

IEC 60439-1 : 2004 Low-voltage switchgear and controlgearassemblies – Part 1: Type-tested and partially type-tested assemblies

612.511.1




lEC/TR 60755 General requirements for residual current operated protective devices Amendment 2 (1992)

612.411.3.2.1.2

IEC 60904-3: 1989 Photovoltaic devices –Part 3 : Measurement principles for terrestrial photovoltaic (PV) solar devices with reference spectral irradiance data

Part 2 Definitions




IEC 61215: 2005 Crystalline silicon terrestrial photovoltaic (PV) modules – Design qualification and type approval

612.511.1

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