Recommendations for small renewable energy and hybrid systems for rural electrification - Part 9-6: Integrated system - Selection of Photovoltaic Individual Electrification Systems (PV-IES)

IEC 62257-9-6:2008(E) proposes a simple selection procedure and cheap, comparative tests which can be performed in laboratories of developing countries, in order to identify the most suitable model of small Photovoltaic Individual Electrification Systems (PV- IES) up to 500 Wp for a particular rural electrification project from a number of products submitted for test. The tests provided in IEC 62257-9-6 allow assessment of the performance of a PV-IES according to the requirement of the general specification of the project (see IEC/TS 62257-2) and to verify their ability to provide the required service.

Priporočila za sisteme malih obnovljivih virov energije in hibridne sisteme za elektrifikacijo podeželja - 9-6. del: Integrirani sistem - Izbira sistema individualne fotonapetostne elektrifikacije (PV-IES)

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Start Date
19-Sep-2008

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SLOVENSKI STANDARD
SIST-TS IEC/TS 62257-9-6:2009
01-marec-2009
3ULSRURþLOD]DVLVWHPHPDOLKREQRYOMLYLKYLURYHQHUJLMHLQKLEULGQHVLVWHPH]D

HOHNWULILNDFLMRSRGHåHOMDGHO,QWHJULUDQLVLVWHP,]ELUDVLVWHPDLQGLYLGXDOQH

IRWRQDSHWRVWQHHOHNWULILNDFLMH 39,(6

Recommendations for small renewable energy and hybrid systems for rural electrification

- Part 9-6: Integrated system - Selection of Photovoltaic Individual Electrification Systems

(PV-IES)
Ta slovenski standard je istoveten z: IEC/TS 62257-9-6
ICS:
27.160 6RQþQDHQHUJLMD Solar energy engineering
27.190 Biološki viri in drugi Biological sources and
alternativni viri energije alternative sources of energy
SIST-TS IEC/TS 62257-9-6:2009 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS IEC/TS 62257-9-6:2009
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SIST-TS IEC/TS 62257-9-6:2009
IEC/TS 62257-9-6
Edition 1.0 2008-09
TECHNICAL
SPECIFICATION
Recommendations for small renewable energy and hybrid systems for rural
electrification –

Part 9-6: Integrated system – Selection of Photovoltaic Individual Electrification

Systems (PV-IES)
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
ICS 27.160; 27.180 ISBN 2-8318-9997-4
® Registered trademark of the International Electrotechnical Commission
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SIST-TS IEC/TS 62257-9-6:2009
– 2 – TS 62257-9-6 © IEC:2008(E)
CONTENTS

FOREWORD...........................................................................................................................4

INTRODUCTION.....................................................................................................................6

1 Scope...............................................................................................................................7

2 Normative references .......................................................................................................7

3 Terms, definitions and abbreviated terms .........................................................................8

3.1 Terms and definitions ..............................................................................................8

3.2 Abbreviated terms ...................................................................................................9

4 System boundaries...........................................................................................................9

5 System pre-selection ........................................................................................................9

5.1 Services to be provided by the system ....................................................................9

5.2 Specification of a model ..........................................................................................9

5.2.1 General operating conditions .......................................................................9

5.2.2 Design.......................................................................................................10

5.2.3 Components requirements.........................................................................10

5.2.4 Safety issues.............................................................................................10

5.2.5 Installation rules ........................................................................................10

5.2.6 Operation and maintenance rules ..............................................................10

5.2.7 Documentation and marking ......................................................................11

5.3 Pre-selection process............................................................................................11

5.3.1 Elements of the GS to be provided to potential suppliers ...........................11

5.3.2 Answers to be provided by potential suppliers ...........................................11

5.3.3 Pre-selection criteria .................................................................................11

6 Comparative tests ..........................................................................................................12

6.1 General .................................................................................................................12

6.2 Service requirements ............................................................................................12

6.3 Service quality index .............................................................................................12

6.4 Testing programme ...............................................................................................16

6.4.1 General .....................................................................................................16

6.4.2 Test 1: initial inspection and commissioning ..............................................17

6.4.3 Test 2: ability to provide the required service under daylight

favourable conditions.................................................................................18

6.4.4 Test 3: ability to provide the required service under daylight

unfavourable conditions.............................................................................20

6.4.5 Test 4: final inspection...............................................................................22

6.4.6 General conclusion....................................................................................23

Annex A (informative) Data record sheet for visual inspection..............................................25

Annex B (informative) Commissioning records sheet............................................................26

Annex C (informative) Examples of load profiles for comparative tests.................................28

Annex D (informative) Instruction and data record sheet models (according to a load

profile as proposed in Annex A) ............................................................................................30

Bibliography..........................................................................................................................36

Figure 1 – Test 2, Phase A: initial charge cycles...................................................................19

Figure 2 – Test 2, Phase B: operating cycles ........................................................................20

Figure 3 – Test 3, operating cycles .......................................................................................22

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TS 62257-9-6 © IEC:2008(E) – 3 –

Table 1 – Climatic conditions (example)................................................................................10

Table 2 – Suggested minimum values for IP and IK ..............................................................10

Table 3 – Lighting service indexes ........................................................................................13

Table 4 – Radio / TV service indexes....................................................................................14

Table 5 – Refrigeration service indexes ................................................................................14

Table 6 – Testing programme ...............................................................................................16

Table A.1 – Data record sheet for visual inspection (example) ..............................................25

Table B.1 – Commissioning records sheet (example)............................................................26

Table C.1 – Example of loads ...............................................................................................28

Table C.2 – Example of small PV-IES loads (~50 Wp) ..........................................................28

Table C.3 – Example of medium PV-IES loads (~200 Wp) ....................................................28

Table C.4 – Example of large PV-IES loads (~500 Wp).........................................................29

Table C.5 – Example of system load profile to perform test on PV-IES..................................29

Table D.1 – Overview instruction sheet for daily records (example) ......................................30

Table D.2 – Record sheet for lighting service (example) .......................................................31

Table D.3 – Record sheet for radio service (example)...........................................................32

Table D.4 – Record sheet for TV service (example) ..............................................................33

Table D.5 – Record sheet for refrigeration service (example)................................................34

Table D.6 – System daily quality index of service evaluation (example) ................................35

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SIST-TS IEC/TS 62257-9-6:2009
– 4 – TS 62257-9-6 © IEC:2008(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RECOMMENDATIONS FOR SMALL RENEWABLE ENERGY
AND HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –
Part 9-6: Integrated system –
Selection of Photovoltaic Individual
Electrification Systems (PV-IES)
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

The main task of IEC technical committees is to prepare International Standards. In

exceptional circumstances, a technical committee may propose the publication of a technical

specification when

• the required support cannot be obtained for the publication of an International Standard,

despite repeated efforts, or

• the subject is still under technical development or where, for any other reason, there is the

future but no immediate possibility of an agreement on an International Standard.

Technical specifications are subject to review within three years of publication to decide

whether they can be transformed into International Standards.

IEC 62257-9-6, which is a technical specification, has been prepared by IEC technical

committee 82: Solar photovoltaic energy systems.
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SIST-TS IEC/TS 62257-9-6:2009
TS 62257-9-6 © IEC:2008(E) – 5 –

This document is based on IEC/PAS 62111 (1999); it cancels and replaces the relevant parts

of IEC/PAS 62111.
This part of IEC 62257 is to be used in conjunction with the IEC 62257 series.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
82/510/DTS 82/532/RVC

Full information on the voting for the approval of this technical specification can be found in

the report on voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts of IEC 62257 series, under the general title: Recommendations for small

renewable energy and hybrid systems for rural electrification, can be found on the IEC

website.

The committee has decided that the contents of this publication will remain unchanged until

the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in

the data related to the specific publication. At this date, the publication will be

• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
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SIST-TS IEC/TS 62257-9-6:2009
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INTRODUCTION

The IEC 62257 series of documents intends to provide to different players involved in rural

electrification projects (such as project implementers, project contractors, project supervisors,

installers, etc.) documents for the setting up of renewable energy and hybrid systems with a.c.

voltage below 500 V, d.c. voltage below 750 V and power below 100 kVA.
These documents are recommendations:
• to choose the right system for the right place;
• to design the system;
• to operate and maintain the system.

These documents are focused only on rural electrification concentrating on but not specific to

developing countries. They must not be considered as all inclusive to rural electrification. The

documents try to promote the use of renewable energies in rural electrification; they do not

deal with clean mechanisms developments at this time (CO emission, carbon credit, etc.).

Further developments in this field could be introduced in future steps.

This consistent set of documents is best considered as a whole with different parts

corresponding to items for safety, sustainability of systems and at the lowest life cycle cost as

possible. One of the main objectives is to provide the minimum sufficient requirements,

relevant to the field of application that is: small renewable energy and hybrid off-grid systems.

This document and the others of the IEC 62257 series are only guidance and so cannot be

International Standards. Additionally their subject is still under technical development and so

they shall be published as Technical Specifications.
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TS 62257-9-6 © IEC:2008(E) – 7 –
RECOMMENDATIONS FOR SMALL RENEWABLE ENERGY
AND HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –
Part 9-6: Integrated system –
Selection of Photovoltaic Individual
Electrification Systems (PV-IES)
1 Scope

The purpose of this part of IEC 62257 is to propose simple selection procedure and cheap,

comparative tests which can be performed in laboratories of developing countries, in order to

identify the most suitable model of small Photovoltaic Individual Electrification Systems (PV-

IES) up to 500 Wp for a particular rural electrification project from a number of products

submitted for test.

It is different of the scope of IEC 62124, Photovoltaic (PV) stand alone systems – Design

verification, which provides guidance for verifying the design of stand-alone PV systems and

indoor and outdoor tests in order to evaluate the performance of PV systems including PV

generator, battery storage and loads such as lights, TV sets, and refrigerators.

The tests provided in IEC 62257-9-6 allow assessment of the performance of a PV-IES

according to the requirement of the General Specification (GS) of the project (see IEC/TS

62257-2) and to verify their ability to provide the required service. They should be performed

locally, as close as possible to the real site operating conditions.

This document is not a type approval standard. It is a technical specification to be used as

guidelines and does not replace any existing IEC standard on PV systems.
2 Normative references

The following referenced documents are indispensable for the application of this document.

For dated references, only the edition cited applies. For undated references, the latest edition

of the referenced document (including any amendments) applies.

IEC 61215, Crystalline silicon terrestrial photovoltaic (PV) modules – Design qualification and

type approval

IEC 61646, Thin-film terrestrial photovoltaic (PV) modules – Design qualification and type

approval

IEC 61730-1, Photovoltaic (PV) module safety qualification – Part 1: Requirements for

construction

IEC 61730-2, Photovoltaic (PV) module safety qualification – Part 2: Requirements for testing

IEC/TS 62257-2:2004, Recommendations for small renewable energy and hybrid systems for

rural electrification – Part 2: From requirements to a range of electrification systems

IEC/TS 62257-4, Recommendations for small renewable energy and hybrid systems for rural

electrification – Part 4: System selection and design
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SIST-TS IEC/TS 62257-9-6:2009
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IEC/TS 62257-5, Recommendations for small renewable energy and hybrid systems for rural

electrification – Part 5: Protection against electrical hazards

IEC/TS 62257-6, Recommendations for small renewable energy and hybrid systems for rural

electrification – Part 6: Acceptance, operation, maintenance and replacement

IEC/TS 62257-7-1, Recommendations for small renewable energy and hybrid systems for

rural electrification – Part 7-1: Generators – Photovoltaic arrays

IEC/TS 62257-8-1:2007, Recommendations for small renewable energy and hybrid systems

for rural electrification – Part 8-1: Selection of batteries and battery management systems for

stand-alone electrification systems – Specific case of automotive flooded lead-acid batteries

available in developing countries

IEC/TS 62257-9-3, Recommendations for small renewable energy and hybrid systems for

rural electrification – Part 9-3: Integrated system – User interface

IEC/TS 62257-9-4, Recommendations for small renewable energy and hybrid systems for

rural electrification – Part 9-4: Integrated system – User installation

IEC/TS 62257-12-1, Recommendations for small renewable energy and hybrid systems for

rural electrification – Part 12-1: Selection of self-ballasted lamps (CFL) for rural electrification

systems and recommendations for household lighting equipment
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
cycle

sequence of a discharge followed by a charge or a charge followed by a discharge of a

battery under specified conditions
3.1.2
duration of service
number of hours when a load is powered
3.1.3
fulfilment of service
ratio of a measured provided service to a required service
3.1.4
initial charge

commissioning charge given to a new battery to bring it to the fully charged state

3.1.5
period of service
part of the day when a load is powered
3.1.6
reference irradiation

value of irradiation taken in consideration for the design of the system, approved by the

project implementer and specified in the GS of the project
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TS 62257-9-6 © IEC:2008(E) – 9 –
3.1.7
service ratio
extent in which the service required by the GS is fulfilled by the system
3.2 Abbreviated terms
3.2.1
general specification for the project
3.2.2
quality of service index
3.2.3
TWQI
total weighted quality of service
3.2.4
DWQI
daily weighted quality of service
3.2.5
S , S and S
good bad d
S : service ratio under favourable conditions;
good
S : service ratio under unfavourable conditions;
bad
S : daily service ratio
4 System boundaries
A PV-IES comprises the following elements:
• a PV generator including PV modules and support structure;
• a charge controller;
• a storage system (including battery and associated casing);
• adequate wiring, switches and protective devices (see IEC/TS 62257-9-3 and
IEC/TS 62257-9-4);

• loads relevant for the required service (such as lamps, TV set, radio set, and refrigerators).

5 System pre-selection
5.1 Services to be provided by the system

The preliminary socio-economic studies shall provide the project developer with information

on the ability of the customers who will benefit from the project to pay for the service provided.

Then, the project developer shall define within the GS the range of services to be provided as

described in IEC/TS 62257-2 as well as the relative priority of the services to be provided (TV,

lighting, etc.)
5.2 Specification of a model
5.2.1 General operating conditions

The project implementer shall define the operating conditions to which the PV-IES can be

subjected. Examples of such conditions are given in Table 1.
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SIST-TS IEC/TS 62257-9-6:2009
– 10 – TS 62257-9-6 © IEC:2008(E)
Table 1 – Climatic conditions (example)
Nominal operating range Storage - Transport
Temperature
–10 °C to +50 °C –40 °C to +80 °C
Humidity at 28 °C 5 % to 95 %
Atmospheric pressure 860 hPa to 1 060 hPa
5.2.2 Design

For the part of the project which will be implemented through Individual Electrification

Systems, the project developer shall size a range of PV IES able to provide the required

service under the specified operating conditions (see IEC/TS 62257-2). The project

implementer could either:
• specify complete integrated systems, or

• specify the different components for PV-IES in order to realize the integration of these

components through its own system design.

In addition, the project developer shall set up the requirements for the loads relevant for the

service to be provided (such as lamps, TV set, radio set, and refrigerator).
5.2.3 Components requirements

The components of the PV-IES shall comply with the relevant IEC standards and/or the

relevant local regulations if any.

For the selection of batteries, tests recommended in IEC/TS 62257-8-1 shall apply and for the

selection of lamps, tests recommended in IEC/TS 62257-12-1 shall apply.
5.2.4 Safety issues

The project developer shall define the IP degree and IK code of the expected products.

Table 2 gives some values that could be considered as a minimum.
Table 2 – Suggested minimum values for IP and IK
Protection degree Minimum suggested value
IP 34
IK 8
Safety rules shall comply with IEC/TS 62257-5.
5.2.5 Installation rules

The complete installation shall comply with IEC/TS 62257-7-1 and IEC/TS 62257-9-4 and any

local wiring codes.
5.2.6 Operation and maintenance rules

The systems shall be designed in order that operation and maintenance may be performed in

accordance with the specifications given in IEC/TS 62257-6.
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SIST-TS IEC/TS 62257-9-6:2009
TS 62257-9-6 © IEC:2008(E) – 11 –
5.2.7 Documentation and marking

A manual shall also be provided including PV-IES installation and operating guidelines such

as:
• initial operations before first use;
• instructions to use the PV-IES properly;
• mounting the PV module;
• charging instructions;
• maintenance and troubleshooting instructions.
5.3 Pre-selection process
5.3.1 Elements of the GS to be provided to potential suppliers

The project implementer shall supply the annual locally available solar irradiation curve.

NOTE This information could be provided through available laboratory data or through local measurements

performed with a reference cell that will be used afterwards for the comparative tests.

This information as well as the requirements defined in 5.1 and 5.2 shall be provided to

potential suppliers in order to receive proposals for relevant products.
The project implementer could:

• provide load requirements and let the suppliers provide systems to supply the load, or

• provide a complete PV-IES system specification, in order to source complete integrated

PV-IES, or

• provide components requirements in order to source separately the different components

of a PV-IES and realize the integration of these components.
5.3.2 Answers to be provided by potential suppliers

The supplier of the PV-IES and/or of the components shall prove that the PV-IES and/or the

components comply with the relevant IEC standards and IEC 62257 technical specifications.

A technical sheet shall be provided by the supplier in order to demonstrate the ability of its

product to match the requirements defined in 5.1 and 5.2.
5.3.3 Pre-selection criteria

The performances claimed by the manufacturer shall be compared to the performances

required by the GS in order to make a pre-selection of available products.

The following general criteria can be used as an initial help for product pre-selection:

• services characteristics claimed by the manufacturer (duration of service and fulfillment of

service);

• conformity of the modules with the following IEC standards: IEC 61215, IEC 61646,

IEC 61730-1 and IEC 61730-2;

• conformity of the batteries, lamps, etc. with the relevant IEC standards and pre-selection

process of potential products as recommended in the IEC/TS 62257 series;
• battery casing characteristics.

A short list of products potentially able to match the requirements of the GS shall be set up by

the project implementer.
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SIST-TS IEC/TS 62257-9-6:2009
– 12 – TS 62257-9-6 © IEC:2008(E)
6 Comparative tests
6.1 General

After the pre-selection process, samples of products of the short list shall be processed

through comparative technical tests.

IMPORTANT: All the pre-selected systems shall be tested simultaneously in the same local

conditions in order to ensure that they are tested under the same environmental parameters

(irradiation, humidity, temperature, etc.).

Tests could be performed either in outdoor conditions, in local laboratories or in site

conditions (on future customer homes for instance). The systems installation rules provided in

the GS are also applicable to test installations.
6.2 Service requirements

Pre-selected models shall be examined to ensure that they will provide the required services

mentioned in the GS according to the load profile used for the design of the system.

A service is defined by:

• The types of appliances/loads powered by the system (such as lamps, TV set, etc.);

• For each type of appliance:
– the number of appliances that can be simultaneously powered;
– the daily duration of the power supply;
– the fulfilment of the provided service.
6.3 Service quality index
A Quality of service Index (QI) of a system is based on one of these two terms:

• d = duration index, d, is the ratio of the measured daily duration of service compared to

the required daily duration of service;

• f = fulfilment index, f, is the ratio of the measured performance (illuminance for lamps,

temperature for refrigerator, etc.) compared to a reference level required by the GS.

For the different considered services the QI takes into account either, d, or, f:

– for lighting: f;
– for radio: d;
– for TV: d;
– for refrigeration: f.

The systems shall be compared through a Total Weighted Quality of service Index (TWQI )

calculated on the basis of observations and measurements performed during, T, days of

comparative tests.
The TWQI and service ratio (S) are calculated as follows:

Step 1: for each service, calculation every day of either “duration” or “fulfilment”

indexes

The following tables illustrate the necessary index evaluation data and calculation rules.

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SIST-TS IEC/TS 62257-9-6:2009
TS 62257-9-6 © IEC:2008(E) – 13 –
Table 3 – Lighting service indexes
Service Lighting
Requirements Number of lamps N
Daily duration of service
...

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