IEC TS 62862-1-3:2017

Solar thermal electric plants - Part 1-3: General - Data format for meteorological data sets

IEC TS 62862-1-3:2017(E) defines a data format for meteorological data sets. The goal of this document is to reduce efforts for data exchange and to avoid errors caused by misunderstandings due to the application of various different and at times unclear formats.

General Information

• Status: Published
• Publication Date: 28-Nov-2017
• ICS: 27.160 - Solar energy engineering
• Technical Committee: TC 117 - Solar thermal electric plants
• Drafting Committee: PT 62862-1-2 - TC 117/PT 62862-1-2
• Current Stage: PPUB - Publication issued
• Start Date: 29-Nov-2017
• Completion Date: 21-Nov-2017

Overview

IEC TS 62862-1-3:2017 defines a standardized data format for meteorological data sets used in the context of solar thermal electric plants. Its primary goal is to reduce effort and errors in data exchange by prescribing a clear, platform‑independent file structure and metadata conventions that ease sharing measured, modeled, satellite-derived, synthetic and forecast meteorological data for solar energy applications.

Key topics and requirements

• ASCII-based file with structured header: Files begin with a version marker (e.g. #MET_IEC.v1.0) and include a fixed number of header lines before the data section. The header supplies metadata needed to interpret the data.
• Mandatory character set declaration: The second line must declare #characterset (examples include code pages or ISO/IEC-8859‑1) to ensure consistent text interpretation across systems.
• Delimiter and end‑of‑line options: The format supports common delimiters (space, ;, ,, tab) and newline conventions (\n or \r\n) for cross‑platform compatibility.
• Explicit data block markers: Data begins after the #begindata header field and ends with #enddata. Column order matches the channel descriptions defined in the header.
• Time-stamps and averaging: Time format follows ISO 8601 (YYYY‑MM‑DDTHH:MM:SS.ssss). Averaged values must be timestamped at the end of the integration period (meteorological convention); special rules apply for sun elevation/zenith angles to allow correct DNI calculations.
• Comprehensive metadata tables: The specification includes tables for general header fields, intellectual property, location, time, gap treatment, quality control, channel descriptions and variable definitions to standardize metadata and reduce ambiguity.
• Conversion-friendly: Designed to be human-readable ASCII that can be mapped to XML or other exchange formats for web services and simulation tools.

Applications and users

This technical specification is useful for:

• Solar thermal plant designers and engineers performing site assessment and performance modeling
• Meteorologists and data providers preparing meteorological time series for solar energy applications
• Researchers developing typical meteorological years (TMY), forecasted data sets, or synthetic datasets
• Software developers building simulation, resource assessment, or quality‑control tools for Concentrated Solar Power (CSP) and other solar systems
• Operators and analysts sharing data between organizations, vendors and modelling tools

Practical benefits include fewer exchange errors, faster integration into simulation workflows, and standardized metadata that supports automated quality control and reproducible analyses.

Related standards

• ISO 8601 (date/time representation)
• ANSI INCITS 4‑1986 (7‑bit ASCII character set)
• Other parts of the IEC 62862 series for solar thermal electric plants

Keywords: IEC TS 62862-1-3:2017, data format for meteorological data sets, solar thermal electric plants, meteorological file format, ISO 8601, ASCII, metadata, CSP, TMY.

Standards Content (Sample)

IEC TS 62862-1-3 ®
Edition 1.0 2017-11
TECHNICAL
SPECIFICATION
Solar thermal electric plants –
Part 1-3: General – Data format for meteorological data sets
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 20 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 65 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: [e-mail].
IEC TS 62862-1-3 ®
Edition 1.0 2017-11
TECHNICAL
SPECIFICATION
Solar thermal electric plants –

Part 1-3: General – Data format for meteorological data sets

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-4976-5

– 2 – IEC TS 62862-1-3:2017 © IEC 2017
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Format description . 5
5 General conventions . 6
5.1 Character set . 6
5.2 New line . 6
5.3 Time-stamps, integration and averaging . 6
6 Meteorology file format . 7
Bibliography . 19

Table 1 – General header fields . 7
Table 2 – IPR header fields. 9
Table 3 – Location fields . 9
Table 4 – Time fields . 10
Table 5 – Gap treatment . 11
Table 6 – Quality control . 12
Table 7 – Key words for the channel description . 13
Table 8 – Meteorological file format: variables . 15

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SOLAR THERMAL ELECTRIC PLANTS –

Part 1-3: General – Data format for meteorological data sets

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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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 TS 62862-1-3, which is a Technical Specification, has been prepared by IEC technical
committee 117: Solar thermal electric plants.

– 4 – IEC TS 62862-1-3:2017 © IEC 2017
The text of this Technical Specification is based on the following documents:
Draft TS Report on voting
117/68/DTS 117/78/RVDTS
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 document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62862 series, published under the general title Solar thermal
electric plants, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.

SOLAR THERMAL ELECTRIC PLANTS –

Part 1-3: General – Data format for meteorological data sets

1 Scope
The goal of this document on data format is to reduce efforts for data exchange and to avoid
errors caused by misunderstandings due to the application of various different and at times
unclear formats. To achieve this goal, the proposed format has the following properties:
• suitability for common operation systems;
• suitability for satellite/model‐derived data;
• suitability for measured data;
• suitability for combined data sets;
• suitability for typical meteorological years and forecasted data.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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.
ISO 8601, Data elements and interchange formats – Information interchange –
Representation of dates and times
ANSI INCITS 4-1986 (R2007), American National Standard for Information Systems – Coded
Character Sets – 7-Bit American National Standard Code for Information Interchange (7-Bit
ASCII)
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Format description
The data format has been inspired by the thesaurus on solar irradiance proposed at
EnvironInfo 2007.
After a header with information about the data, a data section follows with the meteorological
data. The data section starts after the "#begindata" header field (see Table 1), where the first
line contains the name or acronym of the parameters. The order of the columns is the same
as the order defined on the "channel" description (Table 7). After the data section, the last
line of the file contains "#enddata".

– 6 – IEC TS 62862-1-3:2017 © IEC 2017
The thesaurus is usually implemented in an XML-file format. Many applications in solar
energy tend to use a simpler ASCII data format with values separated by spaces or
semicolons ‘;’, each line standing for one point in time. The proposed data format tries to
combine both, as the data is stored in a simple ASCII format line by line. But it includes a
header which contains all information of the thesaurus. The data can be very easily converted
into an appropriate XML-file to be exchanged via standard web protocols.
Other sources which were used are the depri format which is used in some wind energy
environments (http://depri.org) and the climate and forecasting metadata conventions. For the
available options for delimiters, see Table 1, "#delimiter".
The fieldnames from Tables 1 to 8 are separated from the value of the parameter by a space.
5 General conventions
5.1 Character set
The format shall be based on the standard ASCII character set as defined in
ANSI INCITS 4-1986 (R2007). Using only the first 127 characters will ease exchange of data
between different operating systems. The field "#characterset" is mandatory as a second line
of the file to ease interpretation of the remaining text fields.
5.2 New line
New lines are set by ASCII character 10 (line feed as in UNIX ). Also acceptable is the
combination "Carriage return + line feed" with ASCII characters 13 and 10 (DOS/Windows
new line). When transferring data between DOS/Windows and UNIX type systems, care
should be taken of the different conventions for new lines on each of the systems.
For the available options, see Table 1, "#endofline".
5.3 Time-stamps, integration and averaging
Time stamps follow ISO 8601 YYYY-MM-DDTHH:MM:SS.ssss with leading zeros. Time
stamps for temporally averaged data shall refer to the end of the integration period, as it is
the convention in meteorology. Instantaneous values can also be described by the data
format (see parameter "#time.averaging" in Table 3).
Integration and averaging always refer to the complete time interval. This is especially
important at sunrise and sunset, and it should also include the time frame when the sun is still
or already below the horizon. Limiting such intervals only to the time when the sun is above
the horizon is not allowed.
The only exception is the sun elevation or sun zenith angle. During the sun rise or sunset,
these values should be calculated in a way that allows calculating the DNI from direct
horizontal irradiance using the averaged angles.

___________
UNIX is the trade name of a product supplied by The Open Group. This information is given for the convenience
of users of this document and does not constitute an endorsement by IEC of the product named. Equivalent
products may be used if they can be shown to lead to the same results.
DOS and Windows are the trade names of products supplied by Microsoft Corporation. This information is given
for the convenience of users of this document and does not constitute an endorsement by IEC of the products
named. Equivalent products may be used if they can be shown to lead to the same results.

6 Meteorology file format
Table 1 – General header fields
Field name Data type Unit Complexity mandatory/ Example(s) Description
level optional
#MET_IEC.v1.0 headerlines: String 1 m #MET_IEC.v1.0 headerlines:57 Indicates that this is a meteorological data
number_of_headerlines file of the IEC document. It gives the version
number. The last field is the number of
header lines in the field until the data begins
(line number of the line "#begindata").
Header name and number of header lines
have to be written in one line.
#characterset String 1 m #characterset 850 This is a mandatory second line of the file.
#characterset ISO/IEC-8859-1
Defines which extended character set has
been used for ASCII characters above 127. It
can be an MS-DOS or Windows code-page
indicated by a three- or four-digit number. Or
reference is made to
ISO/IEC 8859 (all parts). In this case, it
should read ISO/IEC-8859-1, for example
Latin-1, the western European version.
String 1 m #delimiter space tab Delimiter between different columns in the
data section. Options are "space", ";", ",", or
#delimiter
"tab". A combination of different delimiters is
not allowed.
String 1 m #endofline \n The ASCII character indicates that a new line
#endofline
starts. Options are "\n" or "\n\r".
#title String 1 o #title Plataforma Solar Title of the time series.
#history.timestamp String 1 o #history.2016-02-09T12:30 initial research
The #history field describes the evolution of
the data set, and by whom it has been
processed after the original creation.
"#history" fields should be numbered to
ensure that the order of processing can be
evaluated. Each processing step should be
documented by additional "#history" fields.
If a modification is described in several lines,
the order of the lines can be kept by
marginally increasing the timestamp.
#comment String 1 o #comment this is a general comment General comments

– 8 – IEC TS 62862-1-3:2017 © IEC 2017

Field name Data type Unit Complexity mandatory/ Example(s) Description
level optional
#datasource String 1 m #datasource measured Indicator of which type of data is in the file:
"measured", "modelled", "synthetic", "mixed",
"satellite", "NWP".
"measured" or "modelled" data refer to a real
time series. "synthetic" means an artificial
data set with no real time reference.
Examples are typical meteorological data
sets or data from algorithms that generate
data sets. "mixed" indicates that the file
contains data from several categories, for
example measured and modelled data.
"forecast" indicates that the data is
forecasted data.
#status_update String 1 o #status_update 2015-01-01T12:45 2015-03- Describes status updates within the data set,
begindateenddate text 02T09:00 Failure of sensor 1. for example sensor failures, cleaning events,
external influences, etc.
Timestamps follow ISO 8601.
#begindata String 1 m #begindata Beginning of the data section.
time "sign of second column" time ghi
...