IEC 60904-10-2020 pdf free download – Photovoltaic devices – Part 10: Methods of linear dependence and linearity measurements.
This part of IEC 60904 describes the procedures used to measure the dependence of anyelectrical parameter (Y) of a photovoltaic (PV) device with respect to a test parameter(X) andto determine the degree at which this dependence is close to an ideal linear (straight-line)function. lt also gives guidance on how to consider deviations from the ideal lineardependence and in general on how to deal with non-linearities of PV device electricalparameters. Typical device parameters are the short-circuit current Isc，the open-circuitvoltage Voc and the maximum power Pmax.Typical test parameters are the temperature Tandthe irradiance G.However，the same principles described in this document can be applied toany other test parameter with proper adjustment of the procedure used to vary the parameter itself.
Performance evaluations of PV modules and systems，as well as performance translationsfrom one set of temperature and irradiance to another，frequently rely on the use of linearequations (see for example IEC 60891, IEC 61853-1,IEC 61829 and lEC 61724-1). Thisdocument lays down the requirements for linear dependence test methods, data analysis and acceptance limits of results to ensure that these linear equations will give satisfactory results.Such requirements prescribe also the range of the temperature and irradiance over which the linear equations may be used. This document gives also a procedure on how to correct fordeviations of the short-circuit currentsc from the ideal linear dependence on irradiance(linearity) for PV devices，regardless ofwhether they are classified linear or non-linearaccording to the limits set in 9.7. The impact of spectral irradiance distribution and spectralmismatch is considered for measurements using solar simulators as well as under naturalsunlight.
The measurement methods described herein apply to all PV devices,with some caution to beused for multi-junction PV devices, and are intended to be carried out on a device, or in some cases on an equivalent device of identical technology,that is stable according to the criteriaset in the relevant part of IEC 61215. These measurements are meant to be performed priorto all measurements and correction procedures that require a linear device or that prescriberestrictions for non-linear devices.
The main methodology used in this document is based on a fitting procedure in which a linear (straight-line) function is fitted to a set of measured data points {X y }. The linear functionuses a least-squares “fit calculation routine,which in the most advanced analysis alsoaccounts for the expanded combined uncertainty(k=2) of the measurements. The linearfunction crosses the origin in the case of short-circuit current data versus irradiance. Thedeviation of the measured data from the ideal linear function is also calculated and limits areprescribed for the permissible percentage deviation.
Procedures to determine the deviation of the Y(X) dependence from the linear (straight-line)function are described in Clause 6 (measurements’under natural sunlight and with solarsimulator)， Clause 7 (differential spectral responsivitymeasurements) and Clause 8(measurements via two-lamp and N-lamp method). Data analyses to determine the deviations from the linear function are given in Clause 9.
A device is considered linear for the specific measured dependence Y(X)， when it meets therequirements of 9.7.
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 60904-10 pdf download.