IEC 60904-4-2019 pdf download.Photovoltaic devices – Part 4: Reference solar devices – Procedures for establishing calibration traceability (IEC 60904-4:2019).
This part of IEC 60904 sets the requirements for calibration procedures intended to establish the traceability of photovoltaic (PV) reference devices to SI units as required by IEC 60904-2.
This document applies to PV reference devices that are used to measure the irradiance of natural or simulated sunlight for the purpose of quantifying the performance of PV devices.
The use of a PV reference device is required in many standards concerning PV (e.g. IEC 60904-1 and IEC 60904-3).
This document has been written with single-junction PV reference devices in mind, in particular crystalline silicon, but it is sufficiently general to include other single-junction technologies.
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.
IEC 60904-1 , Photovoltaic devices – Part 1: Measurement of photovoltaic current-voltage characteristics
IEC 60904-2, Photovoltaic devices – Part 2: Requirements for photovoltaic reference devices
IEC 60904-3, Photovoltaic devices – Part 3: Measurement principles for terrestrial photovoltaic (PV) solar devices with reference spectral irradiance data
IEC TS 61 836, Solar photovoltaic energy systems – Terms, definitions and symbols
ISO/IEC Guide 98-3: 2008, Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement (GUM: 1995)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC TS 61 836 and the following apply.
NOTE The different reference instruments for the traceability chain of solar irradiance are defined in this clause.
Typical examples for each category are listed in Table 1 , which also refers to relevant standards (where available).
Figure 1 then shows schematically the most common traceability chains linking these instruments and the relevant standards (where available). Methods for the implementation of this document are described in Annex A.
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
3.1 primary standard
standard that is designated or widely acknowledged as having the highest metrological qualities and whose value is accepted without reference to other standards of the same quantity
Note 1 to entry: The concept of a primary standard is equally valid for base quantities and derived quantities.
Note 2 to entry: A primary standard is never used directly for measurement other than for comparison with other primary standards or secondary standards.
Note 3 to entry: Primary standards are usually maintained by national metrology institutes (NMIs) or similar organizations entrusted with maintenance of standards for physical quantities. Often referred to also just as the «primary», the physical implementation is selected such that long-term stability, accuracy and repeatability of measurement of the quantity it represents are guaranteed to the maximum extent possible by current technology.
Note 4 to entry: The World Radiometric Reference (WRR) as realized by the World Standard Group (WSG) of cavity radiometers is the accepted primary standard for the measurement of solar irradiance.
3.2 secondary standard
device which, by periodical comparison with a primary standard, serves to maintain conformity to SI units at other places than that of the primary standard
Note 1 to entry: A secondary standard does not necessarily use the same technical principles as the primary standard, but strives to achieve similar long-term stability, accuracy and repeatability.
Note 2 to entry: Typical secondary standards for solar irradiance are cavity radiometers which participate periodically (normally every 5 years) in the International Pyrheliometer Comparison (IPC) with the WSG, thereby giving traceability to WRR. Direct traceability to SI radiometric scale can also be available for these instruments.IEC 60904-4 pdf download.