SRI LANKA STANDARD CODE OF PRACTICE FOR GRID CONNECTED PHOTOVOLTAIC POWER SYSTEMS

SLS 1522:2016

BYH S W Karunaratne

Assistant Director - EngineeringSri Lanka Standards Institution.

1

DEFINITIONS

• Ac module: PV module with an integrated inverter in which the electrical

terminals are AC only

• module inverter: inverter that is integrated to the output of a single PV

module (A module inverter is usually attached to the rear of a module).

• micro inverter: small inverter designed to be connected directly to one or

two PV modules.

NOTE: A micro inverter will normally connect directly to the factory fitted module leads and

be fixed to the module frame or mounted immediately adjacent to the module. Source: IEC

62446-1:2016

• grid-interactive inverter: an inverter or inverter function intended to

export power to the grid

NOTE: Also commonly referred to as “grid-connected”, “grid-tied”, “utility-interactive”.

Power exported may or may not be in excess of the local load. IEC 62109-2 :2011

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OBJECTIVES• To Improve the safety, performance and reliability of solar

photovoltaic power systems installed in the field.

• To Encourage industry Best Practice for all design andinstallation work involving solar photovoltaic power systems.

• To Provide a network of competent solar photovoltaic powersystem designers and installers.

• To Increase the uptake of solar photovoltaic power systems, bygiving customers increased confidence in the design andinstallation work.

• To performance of a reliable installation that fulfils customerexpectations requires both careful design and correctinstallation practice. Compliance with relevant state health andsafety regulations is also necessary and any other regulatoryrequirement imposed by other relevant bodies.

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SCOPEThis Sri Lanka Standard defines the minimal informationand documentation required to be handed over to acustomer following the installation of a grid connected PVsystem. This standard also describes the installation,testing & commissioning procedure and documentationexpected to verify the safe installation and correctoperation of the system. This document can also be usedfor periodic retesting.

This standard is written for grid connected net energymetered solar PV systems only and not for AC modulesystems or systems that utilize energy storage (e.g.batteries) or hybrid systems.

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SCOPE con.

• This standard is for use by system designers and installersof grid connected net energy metered solar PV systems as atemplate to provide effective documentation to a customer.By detailing the expected installation, testing &commissioning procedure, it is also intended to assist inthe verification / inspection of a grid connected PV systemafter installation and for subsequent re-inspection,maintenance or modifications.

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SYSTEM DOCUMENTATION

• System Data

– Basic system information

– System designer information

– System installer information

• Wiring diagram

– Array - general specifications

– PV string information

– Array electrical details

– Earthing and overvoltage protection

– AC system

• Datasheets

– PV Module

– Inverter

• Mechanical design information

• Operation and maintenance information

• Test results and commissioning data

This information will ensure key system data is readily available to acustomer, inspector or maintenance engineer.

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PV ARRAY INSTALLATION

• Roof mounting Structure

– Ensure that the suitability of the roof support structure can withstand additional loads (array frames structure, PV modules and wind load)

– Sufficient space below the array ( minimum 50 mm)

• Earthing of array

– All exposed parts of module frame and mounting frame shall be earthed.

• Wiring of array

• PV array cable between array and inverter

• String or array protection

– Due to short circuit in module, junction boxes, combiner boxes, module wiring or earth fault

• PV array isolator at array

– Switch-disconnector shall be installed adjacent to the PV array

– Switch-disconnector shall be installed adjacent to the inverter, if distance between inverter and array more than 3m.

PV array maximum voltages shall not greater than 1 000 V d.c.. The Modules thatare electrically in the same string shall be all in the same orientation andminimum tilt angle is 10°

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INVERTER INSTALLATION

• PV array Isolator near inverter

– Inverters with an integrated switch-disconnector, a separate switch-disconnector is not required if the switch-disconnector is mechanically interlocked.

• AC Isolator near inverter

– Inverter is not adjacent to the a.c. isolator with overcurrent protection, it shall be provided at the inverter. It shall be under manual control only.

• AC cable selection

– Shall comply with the wiring requirement of BS 7671 requirements

• Shutdown procedure

• Protection against lightning and overvoltage

The inverter shall be installed as to the manufacturer’s instructions.

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SUPPORTING PRODUCT STANDARDS

SLS 1542:2016 Electric cables for photovoltaic systems

SLS 1543 Safety of power converters for use in photovoltaic power systems –

Part 1:2016 General requirements

Part 2:2016 Particular requirements for inverters

SLS 1544 Terrestrial photovoltaic (PV) modules – Design qualification and type

approval –

Part 1:2016 Test requirements

Part 1-1:2016 Special requirements for testing of crystalline silicon photovoltaic

(PV) Modules

Part 2:2016 Test procedures

SLS 1545 Photovoltaic (PV) module performance testing and energy rating –

Part 1:2016 Irradiance and temperature performance measurements and power

rating

Part 2: 2017 Spectral responsivity, incidence angle and module operating

temperature measurements

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SUPPORTING PRODUCT STANDARDS

SLS 1546:2016 Photovoltaic systems – Power conditioners – Procedure for measuring

efficiency

SLS 1547:2016 photovoltaic (PV) Systems – Characteristics of the utility interface.

SLS 1553 Photovoltaic (PV) module safety qualification –

Part 1: 2017 Requirements for construction

Part 2: 2017 Requirements for testing

SLS 1554 - Low-voltage switchgear and controlgear –

Part 1: 2017 General rules

Part 2: 2017 Circuit-breakers

Part 3: 2017 Switches, disconnectors, switch-disconnectors and fuse-combination

units.

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SLS 1542:2016 - (EN 50618:2014)

ELECTRIC CABLES FOR PHOTOVOLTAIC

SYSTEMS

SCOPE: This standard applies to low smoke halogen

free, flexible, single core power cables with cross link

insulation and sheath. In particular for use at the direct

current (d.c.) side of photovoltaic system, with a nominal

d.c. voltage of 1.5kV between conductors and between

conductor and earth.

The cables are suitable to be used with Class II

equipment.

The cable are design to operate at a nominal maximum

conductor temperature of 90 °C, but for a maximum of 20

000 hours a max. conductor temperature of 120 °C at a

max. ambient temperature of 90 °C is permitted.11

SLS 1543 - (IEC 62109-1:2010)

SAFETY OF POWER CONVERTERS FOR USE

IN PHOTOVOLTAIC POWER SYSTEMS

• Part 1:2016 General requirements

• Part 2:2016 Particular requirements for inverters

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• SCOPE: This part of IEC 62109 applies to the power

conversion equipment (PCE) for use in Photovoltaic

(PV) systems where a uniform technical level with

respect to safety is necessary. This standard defines the

minimum requirements for the design and manufacture

of PCE for protection against electric shock, energy, fire,

mechanical and other hazards.

This standard provides general requirements applicable

to all types of PV PCE. There are additional parts of this

standard that provide specific requirements for the

different types of power converters, such as Part 2 -

inverters. Additional parts may be published as new

products and technologies are commercialised.

Part 1:2016 General requirements

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• EQUIPMENT INCLUDED IN SCOPE: This standard

covers PCE connected to systems not exceeding

maximum PV source circuit voltage of 1 500 V d.c. The

equipment may also be connected to systems not

exceeding 1 000 V a.c. at the a.c. mains circuits, non-

mains a.c. load circuits, and to other DC source or load

circuits such as batteries. This standard may be used for

accessories for use with PCE,

except where more appropriate standards exist.

Evaluation of PCE to this standard includes evaluation

of all features and functions incorporated in or available

for the PCE, or referred to in the documentation

provided with the PCE, if such features or functions can

affect compliance with the requirements of this standard.

Part 1:2016 General requirements

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• EQUIPMENT FOR WHICH OTHER

REQUIREMENTS MAY APPLY:

This standard has not been written to address

characteristics of power sources other than photovoltaic

systems, such as wind turbines, fuel cells, rotating

machine sources, etc.

Additional or other requirements are necessary for

equipment intended for use in explosive atmospheres

(see IEC 60079), aircraft, marine installations,

electromedical applications (see IEC 60601) or at

elevations above 2 000 m.

Part 1:2016 General requirements

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SLS 1544 - (IEC 61215:2016) TERRESTRIAL

PHOTOVOLTAIC (PV) MODULES – DESIGN

QUALIFICATION AND TYPE APPROVAL

• Part 1:2016 Test requirements

• Part 1-1:2016 Special requirements for testing of

crystalline silicon photovoltaic (PV) Modules

• Part 2:2016 Test procedures

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• SCOPE: This part of IEC 61215 lays down IEC requirements for the design

qualification and type approval of terrestrial photovoltaic (PV) modules suitable for

long-term operation in general open-air climates, as defined in IEC 60721-2-1. This

standard is intended to apply to all terrestrial flat plate module materials such as

crystalline silicon module types as well as thinfilm modules.

This standard does not apply to modules used with concentrated sunlight although it

may be utilized for low concentrator modules (1 to 3 suns). For low concentration

modules, all tests are performed using the current, voltage and power levels expected

at the design concentration.

This standard does not address the particularities of PV modules with integrated

electronics, nit may however be used as a basis for testing such PV modules.

The objective of this test sequence is to determine the electrical and thermal

characteristics of the module and to show, as far as possible within reasonable

constraints of cost and time, that the module is capable of withstanding prolonged

exposure in climates described in the scope. The actual lifetime expectancy of

modules so qualified will depend on their design, their environment and the

conditions under which they are operated.

Part 1:2016 Test requirements

17

• SCOPE: This part of IEC 61215 lays down IEC requirements for the design

qualification and type approval of terrestrial photovoltaic modules suitable for long-

term operation in general open air climates, as defined in IEC 60721-2-1. This

standard is intended to apply to all crystalline silicon terrestrial flat plate modules.

This standard does not apply to modules used with concentrated sunlight although it

may be utilized for low concentrator modules (1 to 3 suns). For low concentration

modules, all tests are performed using the current, voltage and power levels expected

at the design concentration.

The object of this test sequence is to determine the electrical and thermal

characteristics of the module and to show, as far as possible within reasonable

constraints of cost and time, that the module is capable of withstanding prolonged

exposure in climates described in the scope. The actual lifetime expectancy of

modules so qualified will depend on their design, their environment and the

conditions under which they are operated.

This standard defines PV technology dependent modifications to the testing

procedures and requirements per IEC 61215-1:2016 and IEC 61215-2:2016.

Part 1-1:2016 Special requirements for testing of

crystalline silicon photovoltaic (PV) Modules

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• SCOPE: This International Standard series lays down IEC requirements

for the design qualification and type approval of terrestrial photovoltaic

modules suitable for long-term operation in general open-air climates, as

defined in IEC 60721-2-1. This part of IEC 61215 is intended to apply to all

terrestrial flat plate module materials such as crystalline silicon module

types as well as thin-film modules.

• This standard does not apply to modules used with concentrated sunlight

although it may be utilized for low concentrator modules (1 to 3 suns). For

low concentration modules, all tests are performed using the current,

voltage and power levels expected at the design concentration.

• The objective of this test sequence is to determine the electrical and thermal

characteristics of the module and to show, as far as possible within

reasonable constraints of cost and time, that the module is capable of

withstanding prolonged exposure in general open-air climates. The actual

lifetime expectancy of modules so qualified will depend on their design,

their environment and the conditions under which they are operated.

Part 2:2016 Test procedures

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SLS 1545 PHOTOVOLTAIC (PV) MODULE

PERFORMANCE TESTING AND ENERGY

RATING

• Part 1:2016 (IEC 61853-1:2011) Irradiance and

temperature performance measurements and

power rating

• Part 2: 2017 (IEC 61853-2:2016) Spectral

responsivity, incidence angle and module

operating temperature measurements

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• SCOPE: This part of IEC 61853 describes requirements for evaluating PV

module performance in terms of power (watts) rating over a range of

irradiances and temperatures. IEC 61853-2 describes test procedures for

measuring the performance effect of angle of incidence; the estimation of

module temperature from irradiance, ambient temperature and wind speed;

and impact of spectral response on energy production. IEC 61853-3

describes the calculations of PV module energy (watt-hours) ratings. IEC

61853-4 describes the standard time periods and weather conditions that

can be utilized for calculating standardized energy ratings.

• The object of this part of IEC 61853 is to define a testing and rating system,

which provides the PV module power (watts) at maximum power operation

for a set of defined conditions. A second purpose is to provide a full set of

characterization parameters for the module under various values of

irradiance and temperature. This set of measurements is required in order to

perform the module energy rating described in IEC 61853-3.

Part 1:2016 (IEC 61853-1:2011)

Irradiance and temperature performance

measurements and power rating

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Part 2: 2017 (IEC 61853-2:2016)

Spectral responsivity, incidence angle and module

operating temperature measurem

• SCOPE: The IEC 61853 series establishes IEC requirements for

evaluating PV module performance based on power (watts), energy (watt-

hours) and performance ratio (PR). It is written to be applicable to all PV

technologies, but may not work well for any technology where the module

performance changes with time (e.g. modules change their behaviour with

light or thermal exposure), or which experience significant non-linearities

in any of their characteristics used for the modelling.

• The purpose of this part of IEC 61853 is to define measurement procedures

for measuring the effects of angle of incidence of the irradiance on the

output power of the device, to determine the operating temperature of a

module for a given set of ambient and mounting conditions and measure

spectral responsivity of the module. A second purpose is to provide a

characteristic set of parameters which will be useful for detailed energy

predictions. The described measurements are required as inputs into the

module energy rating procedure described in IEC 61853-3.

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SLS 1546:2016 - (IEC 61683:1999) PHOTOVOLTAIC

SYSTEMS – POWER CONDITIONERS – PROCEDURE

FOR MEASURING EFFICIENCY

• SCOPE: This standard describes guidelines for measuring the

efficiency of power conditioners used in stand-alone and utility-

interactive photovoltaic systems, where the output of the power

conditioner is a stable a.c. voltage of constant frequency or a stable

d.c. voltage. The efficiency is calculated from a direct measurement

of input and output power in the factory. An isolation transformer is

included where it is applicable.

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SLS 1547:2016 (IEC 61727:2004)

PHOTOVOLTAIC (PV) SYSTEMS –

CHARACTERISTICS OF THE UTILITY

INTERFACE.

• SCOPE: This International Standard applies to utility-interconnected

photovoltaic (PV) power systems operating in parallel with the utility and

utilizing static (solid-state) non-islanding inverters for the conversion of DC

to AC. This document describes specific recommendations for systems

rated at 10 kVA or less, such as may be utilized on individual residences

single or three phase. This standard applies to interconnection with the low-

voltage utility distribution system.

• The object of this standard is to lay down requirements for interconnection

of PV systems to the utility distribution system.

NOTE 1: An inverter with type certification meeting the standards as detailed in this

standard should be deemed acceptable for installation without any further testing.

• This standard does not deal with EMC or protection mechanisms against

islanding.

NOTE 2: Interface requirements may vary when storage systems are incorporated or

when control signals for PV system operation are supplied by the utility.

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Harmonics and waveform distortion

• Table 1 – Current distortion limits

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Odd harmonics Distortion limit

3rd through 9th Less than 4

11th through 15th Less than 2

17th through 21st Less than 1

23rd through 33rd Less than 0

Even harmonics Distortion limit

2nd through 8th Less than 1

10th through 32nd Less than 0

Table 2 – Response to abnormal voltages

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Voltage (at point of utility

connection)

Maximum trip time*

V < 0.5 x V nominal 0.1 s

50 % V < 85 % 2.0 s

85 % V 110 % Continuous operation

110 % < V < 135 % 2.0 s

135 % V 0.05 s

Trip time refers to the time between the abnormal condition occurring and

the inverter ceasing to energize the utility line. The PV system control

circuits shall actually remain connected to the utility to allow sensing of

utility electrical conditions for use by the “reconnect” feature.

Table 2. of guide line and procedures document

Utility grid parameters

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Parameter Value

Maximum output voltage of the

inverter

230Vrms (±6% of the nominal grid

voltage)

Flicker IEC61000-3-3 (less than 16A per

phase), IEC61000-3-5 (greater than

75A)

DC injection1% of the rated inverter output

current (IEC 61727)

Frequency range 50±1%Hz

Total harmonic distortion < 5%

Power factor Lagging power factor greater than

0.90 at the 50% of rated inverter

output power

Islanding protection De-energized within 2 S

SLS 1553 PHOTOVOLTAIC (PV) MODULE

SAFETY QUALIFICATION

• Part 1: 2017 (IEC 61730-1:2016)

Requirements for construction

• Part 2: 2017 (IEC 61730-2:2016)

Requirements for testing

28

• SCOPE: This part of IEC 61730 specifies and describes the fundamental

construction requirements for photovoltaic (PV) modules in order to

provide safe electrical and mechanical operation. Specific topics are

provided to assess the prevention of electrical shock, fire hazards, and

personal injury due to mechanical and environmental stresses. This part of

IEC 61730 pertains to the particular requirements of construction. IEC

61730-2 defines the requirements for testing.

• This International Standard series lays down IEC requirements of terrestrial

photovoltaic modules suitable for long-term operation in open-air climates.

This standard is intended to apply to all terrestrial flat plate module

materials such as crystalline silicon module types as well as thin-film

modules.

• PV modules covered by this standard are limited to a maximum DC system

voltage of 1 500 V.

Part 1: 2017 (IEC 61730-1:2016)

Requirements for construction

29

• SCOPE: The scope of IEC 61730-1 is also applicable to this part of IEC 61730.

While IEC 61730-1 outlines the requirements of construction, this part of the

standard lists the tests a PV module is required to fulfill for safety qualification. IEC

61730-2 is applied for safety qualification only in conjunction with IEC 61730-1.

• The sequence of tests required in this standard may not test for all possible safety

aspects associated with the use of PV modules in all possible applications. This

standard utilizes the best sequence of tests available at the time of its writing. There

are some issues – such as the potential danger of electric shock posed by a broken

PV module in a high voltage system – that should be addressed by the system design,

location, restrictions on access and maintenance procedures.

• The objective of this standard is to provide the testing sequence intended to verify

the safety of PV modules whose construction has been assessed by IEC 61730-1. The

test sequence and pass criteria are designed to detect the potential breakdown of

internal and external components of PV modules that would result in fire, electric

shock, and/or personal injury. The standard defines the basic safety test requirements

and additional tests that are a function of the PV module end-use applications. Test

categories include general inspection, electrical shock hazard, fire hazard,

mechanical stress, and environmental stress.

Part 2: 2017 (IEC 61730-2:2016)

Requirements for testing

30

SLS 1554 - LOW-VOLTAGE

SWITCHGEAR AND CONTROLGEAR

• Part 1: 2017 (IEC 60947-1:2014) General rules

• Part 2: 2017 (IEC 60947-2:2016) Circuit-

breakers

• Part 3: 2017 (IEC 60947-3:2015) Switches,

disconnectors, switch-disconnectors and fuse-

combination units

31

• SCOPE: The purpose of this standard is to harmonize as far as

practicable all rules and requirements of a general nature applicable

to low-voltage switchgear and controlgear in order to obtain

uniformity of requirements and tests throughout the corresponding

range of equipment and to avoid the need for testing to different

standards.

• All those parts of the various equipment standards which can be

considered as general have therefore been gathered in this standard

together with specific subjects of wide interest and application, e.g.

temperature-rise, dielectric properties, etc.

• For each type of low-voltage switchgear and controlgear, only two

main documents are necessary to determine all requirements and

tests:

Part 1: 2017 (IEC 60947-1:2014)

General rules

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• SCOPE: This part of IEC 60947 series applies to circuit-breakers,

the main contacts of which are intended to be connected to circuits,

the rated voltage of which does not exceed 1 000 V a.c. or 1 500 V

d.c.; it also contains additional requirements for integrally fused

circuit-breakers.

• Circuit-breakers rated above 1 000 V a.c. but not exceeding 1 500 V

a.c. may also be tested to this standard.

• It applies whatever the rated currents, the method of construction or

the proposed applications of the circuit-breakers may be.

Part 2: 2017 (IEC 60947-2:2016)

Circuit-breakers

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• SCOPE: This part of IEC 60947 applies to switches, disconnectors,

switch-disconnectors and fuse combination units to be used in

distribution circuits and motor circuits of which the rated voltage

does not exceed 1 000 V a.c. or 1 500 V d.c.

• The manufacturer shall specify the type, ratings and characteristics

according to the relevant standard of any incorporated fuses.

• This part does not apply to equipment coming within the scope of

IEC 60947-2, IEC 60947-4-1 and IEC 60947-5-1; however, when

switches and fuse-combination units coming into the scope of this

part are normally used to start, accelerate and/or stop an individual

motor they shall also comply with the additional requirements given

in Annex A.

Part 3: 2017 (IEC 60947-3:2015)

Switches, disconnectors, switch-

disconnectors and fuse-combination units

34

PV array diagram – multiple parallel string case with array divided in to sub-arrays

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