IEC 60904-10:2020 pdf free download – Photovoltaic devices
1 Scope
This part of lEC 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 T andthe 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 parameteritself.
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 andacceptance 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 thelinear equations may be used. This document gives also a procedure on how to correct fordeviations of the short-circuit current Isc from the ideal linear dependence on irradiance(linearity) for PV devices,regardless of whether 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 somecases on an equivalent device of identical technology, that is stable according to the criteriaset in the relevant part of lEC 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 responsivity measurements) and Clause 8(measurements via two-lamp and N-lamp method).Data analyses to determine the deviationsfrom 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.
5.1General requirements common to all procedures
The following requirements and recommendations are valid for all linear dependences and forall measurement procedures,unless explicitly specified differently. Requirements andrecommendations that are specific to the apparatuses used for each type of measurement aregiven in the following subclauses.
Light sources characterised by intense peaks over a broad continuum, like for example Xenonsources or some lamps based on light emitting diodes (LEDs), should be carefully evaluatedbefore use. Indeed， for some PV devices and/or technologies the spectral responsivity canvary with temperature as well as with irradiance level.Therefore, it can pass through variousemission lines in the lamp spectrum as temperature or irradiance varies. When this occurs,itcan cause shifts in performance that are related mainly to a change in the interaction betweenthe band gap region of the spectral responsivity and the actual spectral irradiance in the samewavelength range. lf this possibility is not properly assessed in each specific case, such shiftscould be misinterpreted as deviations from the linear dependence while they are not.However, based on the measured DUT spectral responsivity as a function of temperature or ofirradiance (depending on what applies) and on the measured spectral irradiance,themagnitude of this effect can be calculated by performing a SMM calculation according toIEC 60904-7 as a function of temperature or of irradiance (depending on what applies).Someguidance on how to do this is reported in the Bibliography.The SMM calculation can then beapplied as SMM correction to every single measurement at all temperatures different from25 C or irradiance levels other than 1 0oo W/m2 (depending on what applies). lf the changein SMM is not larger than 1 % over the entire range of temperatures or than +0,5 % forirradiances,it may alternatively be included as component of the SMM uncertainty in themeasurement uncertainty calculation.