Improving the long-term stability of perovskite solar cells is critical to the deployment of this technology. Despite the great emphasis laid on stability-related investigations, publications lack consistency in experimental procedures and parameters reported. It is therefore challenging to reproduce and compare results and thereby develop a deep understanding of degradation mechanisms. Here, we report a consensus between researchers in the field on procedures for testing perovskite solar cell stability, which are based on the International Summit on Organic Photovoltaic Stability (ISOS) protocols. We propose additional procedures to account for properties specific to PSCs such as ion redistribution under electric fields, reversible degradation and to distinguish ambient-induced degradation from other stress factors. These protocols are not intended as a replacement of the existing qualification standards, but rather they aim to unify the stability assessment and to understand failure modes. Finally, we identify key procedural information which we suggest reporting in publications to improve reproducibility and enable large data set analysis.

This paper describes the measurement of photovoltaic module performance over a range of temperatures and irradiances according to the international standard IEC 61853 Part 1. The purpose of this work is to assess the reproducibility of power matrix measurements obtained using two methods specified in the standard: under natural sunlight with a tracker, and with a solar simulator. A comparison of results using the third principal method (under natural sunlight without tracker) is also summarised for completeness. The same measurement techniques have been employed to measure four modules of different technologies, namely mono and poly crystalline Si, CdTe and CIS. The method used to vary the irradiance in the natural sunlight with tracker and solar simulator approaches is based on un-calibrated mesh filters. The uniformity and effect on spectrum of the mesh filters have been studied, and the impact of these on the measurements estimated. Measurements from all methods are compared over as much of the ranges as possible. The results show that for all modules, the reproducibility is within the estimated measurement uncertainty. The suitability of the different methods is discussed in light of the results and the limitations of the various methods as applied to different modules technologies. On the basis of the results, parts of IEC 61853 Part 1 will be introduced into the ISO 17025 laboratory accreditation at the European Solar Test Installation (ESTI).

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Performance measurements of photovoltaic devices, including metastable ones, should reflect as closely as possible the behaviour of these devices when deployed in the field, i.e. at constant illumination and fixed conditions. We review the wide-ranging behaviour observed in and previously proposed measurement solutions for perovskite solar cells (PSC) devices and further illustrate the variability during measurement with recent examples from our own experience. We propose a generic measurement protocol for PSC devices to ensure that electrical characterisation under simulated sunlight reflects real life conditions. The approach focusses on determining the steady-state maximum-power output under continuous illumination rather than relying on the I–V characteristics. Given the large variations in device behaviour, this protocol is particularly suitable in cases where a priori information about the devices under test is not available. We conclude that the approach to the electrical characterisation of PSC devices should shift from traditional I–V curves to the maximum-power output under steady-state conditions. The latter is the simplest and most reliable method to evaluate, assess and compare PSC technologies when power and efficiency reporting are required. This protocol also contributes to harmonising comparison between different calibration laboratories thus contributing to increased confidence in the results.

Accuratecharacterizationandreportingoforganicphotovoltaic(OPV)deviceperformanceremainsone\ud of theimportantchallengesinthe field. Thelargespreadamongtheefficiencies ofdeviceswiththesame\ud structure reportedbydifferentgroupsissignificantly causedbydifferentproceduresandequipment\ud used duringtesting.Thepresentedarticleaddressesthisissuebyofferinganewmethodofdevice\ud testing using “suitcase sample” approach combinedwithoutdoortestingthatlimitsthediversityofthe\ud equipment,andastrictmeasurementprotocol.Aroundrobinoutdoorcharacterizationofroll-to-roll\ud coated OPVcellsandmodulesconductedamong46laboratoriesworldwideispresented,wherethe\ud samples andthetestingequipmentwereintegratedinacompactsuitcasethatservedbothasasample\ud transportation toolandasaholderandtestequipmentduringtesting.Inaddition,aninternetbased\ud coordination wasusedviaplasticphotovoltaics.orgthatallowedfastandefficient communicationamong\ud participants andprovidedacontrolledreportingformatfortheresultsthateasedtheanalysisofthe\ud data. Thereporteddeviationsamongthelaboratorieswerelimitedto5%whencomparedtotheSi\ud referencedeviceintegratedinthesuitcaseandwereupto8%whencalculatedusingthelocalirradiance\ud data. Therefore,thismethodoffersafast,cheapandefficient toolforsamplesharingandtestingthat\ud allowsconductingoutdoormeasurementsofOPVdevicesinareproduciblemanner