IEC 60904-1:2020 pdf download

IEC 60904-1:2020 pdf download.Photovoltaic devices – Part 1: Measurement of photovoltaic current-voltage characteristics
1 Scope
This part of IEC 60904 describes procedures for the measurement of current-voltage characteristics ( I-V curves) of photovoltaic (PV) devices in natural or simulated sunlight. These procedures are applicable to a single PV solar cell, a sub-assembly of PV solar cells, or a PV module. They are applicable to single-junction mono-facial PV devices. For other device types, reference is made to the respective documents, in particular for multi-junction devices to IEC 60904-1-1 and for bifacial devices to IEC TS 60904-1-2. Additionally informative annexes are provided concerning area measurement of PV devices (Annex A), PV devices with capacitance (Annex B), measurement of dark current-voltage characteristics (dark I-V curves) (Annex C) and effects of spatial non-uniformity of irradiance (Annex D). NOTE The methods provided in this document can also be used as guidance for taking I-V curves of PV arrays. For on-site measurement refer to IEC 61829. This document is applicable to non-concentrating PV devices for use in terrestrial environments, with reference to (usually but not exclusively) the global reference spectral irradiance AM1.5 defined in IEC 60904-3. It may also be applicable to PV devices for use under concentrated irradiation if the application uses direct sunlight and reference is instead made to the direct reference spectral irradiance AM1.5d in IEC 60904-3.The purposes of this document are to lay down basic requirements for the measurement of I-V curves of PV devices, to define procedures for different measuring techniques in use and to show practices for minimising measurement uncertainty. It is applicable to the measurement of I-V curves in general. I-V measurements can have various purposes, such as calibration (i.e. traceable measurement with stated uncertainty, usually performed at standard test conditions) of a PV device under test against a reference device, performance measurement under various conditions (e.g. for device temperature and irradiance) such as those required by IEC 60891 (for determination of temperature coefficients or internal series resistance), by IEC 61853-1 (power rating of PV devices) or by IEC 60904-10 (for determination of output’s linear dependence and linearity with respect to a particular test parameter). I-V measurements are also important in industrial environments such as PV module production facilities, and for testing in the field. Further guidance on I-V measurements in production facilities is provided in IEC TR 60904-14. The actual requirements (e.g. for the class of solar simulator) depend on the end-use. Other standards referring to IEC 60904-1 can stipulate specific requirements. Where those requirements are in conflict with this document, the specific requirements take precedence.
4 General requirements
4.1 General For illustration purposes a schematic current-voltage characteristic (I-V curve) is shown in Figure 1 and the corresponding power-voltage characteristic ( P-V curve) in Figure 2.4.2 Measurements a) When the measurements are intended to be reported at standard test conditions (see 4.5) the in-plane average irradiance during measurement shall be between 800 W∙m −2 and 1 200 W∙m −2 to minimise errors arising from large corrections. b) Temperature sensors should be located so as to detect as closely as possible the temperature of the respective device cell junction. If a temperature gradient between the sensor and the cell junction is suspected, an appropriate contribution to the measurement uncertainty should be included. Consideration should also be given to any possible non- uniformity of temperature across either device, particularly for PV modules, where the temperature of individual cells can vary due to their electrical characteristics, particularly when the module is illuminated under short-circuit conditions. The Equivalent Cell Temperature (ECT) method specified in IEC 60904-5 can be useful in dealing with either a temperature gradient or temperature non-uniformity. The cooling effect from airflow (for example due to wind during outdoor measurement or due to air conditioning of the room for indoor measurements) on the temperature sensors should be considered in the uncertainty of the temperature measurement. c) The active surface of the device under test shall be coplanar within ±2° with the active surface of the reference device. d) Voltages and currents shall be measured using independent leads from the terminals of the device under test and keeping them as short as possible. If the device under test is a module, a subassembly or an encapsulated solar cell, the 4-wire connection should start at the terminals or connectors. If the device under test is a bare PV cell, the 4-wire connection should start at the cell bus bars. The connection method for bare cells (i.e. provided without connectors) should be carefully evaluated.