Perovskite mini-modules with two ETL compositions—thick ETL1 (LiF/C 60 /BCP) and thin ETL2 (LiF/C 60 /LiF)—were measured outdoors for over three years to assess long-term performance.

Perovskite mini-modules with two ETL compositions—thick ETL1 (LiF/C 60 /BCP) and thin ETL2 (LiF/C 60 /LiF)—were measured outdoors for over three years to assess long-term performance.

Evolution of Hysteresis Index Based on 2-year Outdoor TestingElias Peraticos a, Vasiliki Paraskeva a, Matthew Norton a, Aranzazu Aguirre b, c, d, Anurag Krishna b, c, d, Tom Aernouts b, c, d, Maria Hadjipanayi aa FOSS Research Centre for Sustainable Energy, Department of Electrical and Computer Engineering, University of Cyprus, 75 Kallipoleos Str., Nicosia, 1678, Cyprusb Hasselt University, imo-imomec, Martelarenlaan 42, 3500 Hasselt, Belgiumc Imec, imo-imomec, Thin Film PV Technology, Thor Park 8320, 3600 Genk, Belgiumd EnergyVille, imo-imomec, Thor Park 8320, 3600 Genk, BelgiumInternational Conference on Hybrid and Organic PhotovoltaicsProceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV24)València, Spain, 2024 May 12th - 15thOrganizer: Bruno EhrlerOral, Elias Peraticos, presentation 019DOI: https://doi.org/10.29363/nanoge.hopv.2024.019Publication date: 6th February 2024Over the last two decades the efficiency of perovskite cells has almost doubled, reaching current values of 26.1 %. However, since the emergence of this technology the phenomenon of hysteresis, that is the difference in the current-voltage (J-V) scans noticed, was observed. This was initially overlooked by the scientific community, thus focussing on the scan with the more favourable efficiency results [1]. Overtime it was realised that the changes taking place within the system, causing the hysteretic effect could not be ignored, as they led to confusion on the performance of the perovskite device. This led to new measurement techniques to combat the phenomenon, by using slower rates of J-V scan during the studies, as well as by measuring the stabilized or steady-state photocurrent at the maximum power point (MPP) voltage. The hysteretic behaviour is still a controversial topic with respect to its origin, however it is important to continue studying it in order to unlock key information about this phenomenon. During this study the perovskite mini-modules used were of the p-i-n architecture. The evolution of the hysteresis index was studied over a period of 2 years. Initially, it was noticed that the hysteresis index, increases with increasing temperature within a fixed irradiance range of 950-1050 W/m2. Similarly, the hysteresis index also seems to increase with irradiance. However, it was noticed that the hysteresis index was larger in the morning than in in the afternoon for the same irradiance values. This is thought to be due to enhanced performance during the morning hours, due to overnight recovery. Furthermore, the diurnal degradation of the hysteresis index is being studied as well as its effect with temperature. References:[1] S. N. Habisreutinger, N. K. Noel, H. J. Snaith, ACS Energy Lett. 2018, 3, 2472−2476.Acknowledgements:This work has been financed by the European Union through the TESTARE project (Grant ID: 101079488) and by the European Regional Development Fund and the Republic of Cyprus through the Cyprus Research and Innovation Foundation and the DegradationLab project (Grant ID: INFRASTRUCTURES/1216/0043). © FUNDACIO DE LA COMUNITAT VALENCIANA SCITOnanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.MATSUSPreviously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.International Conference on Hybrid and Organic PhotovoltaicsInternational Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and OptoelectronicsThe main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and OptoelectronicsThe International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

A holistic approach was utilized in this work to characterize perovskite mini-modules. Outdoor testing in combination with advanced optoelectronic techniques (spatially resolved Electroluminescence/Photoluminescence) were applied for the testing of the devices. In this way, investigation of the power output evolution of the devices in the field as well as study of their defects and shunts evolution will be performed. A considerable reduction of the power output was obtained from the devices exposed outdoors from the first days of testing. Moreover, reference modules of the same structure were kept indoors in dark storage and measured regularly with means of IV and spatially-resolved EL/PL for the study of their performance degradation under dark and controlled conditions indoors.

Several perovskite mini-modules have been installed and tested outdoors for a duration of up to two years. Diurnal performance recovery overnight and diurnal performance degradation of several perovskite samples were calculated for each day in the field demonstrating diurnal values for degradation and recovery up to 30%. Outdoor testing for several months in the field demonstrated the impact of temperature on the major electrical parameters of the devices. Interplay of metastability and temperature effects was detected in the output power temperature coefficient results while agreement was found between indoor and outdoor tests for voltage temperature coefficient results. Finally, perovskite power output time series forecast was implemented for the samples tested for over one year in the field by utilizing different statistical and machine learning methods and gave evidence of good agreement between the actual and predicted power.

Perovskite solar cell devices – although thought to be possible candidates for substituting conventional silicon photovoltaics – display inherent instabilities that complicate the application of traditional characterisation approaches. Hence, conducting measurements for different technologies under varying conditions can help in characterising them as well as contributing to the advancement of their stability needed for commercial success. This work aims to contribute to the growing body of indoor tests aimed at enhancing the understanding and characterisation of this novel technology. Four different types of perovskite technology mini-modules have been tested with different sweep rates to study its impact on the hysteresis effect noticed during full scan current-voltage (I-V) traces. Measurements revealed that the MAPbI 3 perovskite-based devices are more sensitive to sweep rate than the CsFAPbIBr perovskites. The changes noticed in the I-V traces at different sweep rates is thought to be due to different ion migration effects in the perovskite, so finding the appropriate sweep rate for each technology will lead to a better characterisation of these samples.

For the commercialization of perovskite solar cells (PSCs), detection of associated degradation mechanisms and mitigation of their effect is of paramount importance. The former requires outdoor and indoor stability tests to detect these mechanisms under real operation conditions and to accelerate them under controlled environments. Herein, the thermomechanical stability of encapsulated PSCs in outdoor tests at three locations coupled with indoor thermal cycling tests is investigated. Results show that encapsulant-induced partial delamination can occur in outdoor and indoor tests, leading to disruption in device integrity and substantial loss in the cell active area and short-circuit current. The findings suggest that delamination involves C60 and SnO2 layers as the mechanically weakest point in the device stack. To the best of our knowledge, this work is the first demonstration of delamination in encapsulated PSCs under real operation conditions. While partial delamination emerged on some of the cells exposed in Israel and Cyprus in just a few weeks, it did not occur in Germany over 2.5 years of outdoor exposure. This highlights the importance of multiclimate outdoor testing to validate the significance of failure modes observed through accelerated indoor testing. Investigation of encapsulated perovskite solar cells (PSCs) in indoor and outdoor tests reveals thermomechanical stability concerns. Partial delamination particularly affects C60 and SnO2 layers and disrupts device integrity, leading to losses in cell active area and current. Variability in delamination occurrence across outdoor testing locations highlights the necessity of multiclimate outdoor testing.image (c) 2024 WILEY-VCH GmbH

Long-term stability is the primary challenge for the commercialization of perovskite photovoltaics, exacerbated by limited outdoor data and unclear correlations between indoor and outdoor tests. In this study, we report on the outdoor stability testing of perovskite mini-modules conducted over a two-year period. We conducted a detailed analysis of the changes in performance across the day, quantifying both the diurnal degradation and the overnight recovery. Additionally, we employed the XGBoost regression model to forecast the power output. Our statistical analysis of extensive aging data showed that all perovskite configurations tested exhibited diurnal degradation and recovery, maintaining a linear relationship between these phases across all environmental conditions. Our predictive model, focusing on essential environmental parameters, accurately forecasted the power output of mini-modules with a 6.76% nRMSE, indicating its potential to predict the lifetime of perovskite-based devices.

Ensuring optimal performance of solar photovoltaic (PV) systems requires the extensive assessment and un-derstanding of losses of different origin that affect these installations. Soiling is a key loss factor influencing the performance of PV systems, particularly in arid and dry climatic regions, and its thorough knowledge and modelling aspects including the seasonal evolution is challenging for the early stages of energy prospecting for PV power plants. The purpose of this study is to address this fundamental challenge by evaluating the loss of soiling and the performance of six soiling models based on both physical and machine learning (ML) approaches. Specifically, the case study is a soiling test-bench experimental apparatus installed at the outdoor test facility of the University of Cyprus in Nicosia, Cyprus. The climatic conditions of the site represent a dry climate with high PV potential due to high irradiation levels. The obtained results reported soiling rates ranging from 0.039%/day to 0.535%/day depending on the season and the presence of dust episodes. The average yield daily and monthly soiling losses were 1.9% and 2.4% over a 2-year period, respectively. Furthermore, the comparative analysis of the different soiling models illustrated that the physical models achieved slightly better performance than the ML models with root mean square error (RMSE) of 1.16% and 0.83% for daily and monthly losses, respectively. Finally, the findings provide evidence and useful information on the performance and limitations of the different soiling models for fielded PV systems located in arid and dry climatic zones.

The outdoor performance monitoring of perovskite modules over 16 weeks is reported. Two different types of active perovskite layers were studied: one type contained formamidinium chloride (FACl) halide additives and the other contained no additives with the main purpose to investigate performance trends during the outdoor exposure of those type of devices. Long-term side-by-side outdoor testing of devices with and without halide additives was not implemented in the past and merits investigation in order to determine the impact of additives on perovskite performance and stability. Although the two types of modules displayed similar initial outdoor performance characteristics, their outdoor performance evolution differed. Different degradation rates between the modules with and without additives were obtained just after field installation. In particular, the modules with additives exhibited higher performance degradation under open-circuit loading conditions between current-voltage (IV) scans. Long-term monitoring of both modules recorded a reduction of the efficiency over the course of the day with subsequent recovery overnight and in many cases during the day. The relative values of performance degradation and overnight recovery were calculated over the timespan of outdoor testing and indicated dominant normalized diurnal performance degradation in one type of modules (without FACl additives) in the range between 15–20% and in the other type of modules (with additives) 5–10%. The dominant normalized performance recovery values found were 25–30% and 5–10%, respectively. Finally, dark lock-in thermography (DLIT) and Raman studies were performed on the exposed devices and revealed differences in hotspot evolution and vibrational modes between the different types of module.

A long-term outdoor study of photovoltaic mini-modules with different perovskite compositions was undertaken to detect differences in their long-term performance that could be attributed to their composition. Diurnal efficiency degradation and overnight recovery was observed over the outdoor testing period. In addition, the performance recovery of the mini-modules was investigated after their removal from the field to detect differences in the reversible process mechanisms between the different module compositions. Light current-voltage (IV) scans, Resonance Raman spectroscopy techniques and spatially-resolved Electroluminescence (EL) measurements were utilized for this purpose.

The diurnal efficiency degradation and subsequent recovery of several identical perovskite mini-modules has been investigated during outdoor testing over different seasons. Seasonal dependence of recovery and diurnal efficiency degradation in perovskite devices has been demonstrated. The higher irradiation and ambient temperatures during summer months were found to enhance the diurnal efficiency degradation-to-recovery ratio over the first days of testing, leading to significant accelerated performance degradation in the perovskite modules tested in those conditions. Diurnal efficiency degradation and performance recovery were found to be higher at early degradation stages, where higher absolute efficiency values are present.

In photovoltaic power ratings, a single solar spectrum, AM1.5, is the de facto standard for record laboratory efficiencies, commercial module specifications, and performance ratios of solar power plants. More detailed energy analysis that accounts for local spectral irradiance, along with temperature and broadband irradiance, reduces forecast errors to expand the grid utility of solar energy. Here, ground-level measurements of spectral irradiance collected worldwide have been pooled to provide a sampling of geographic, seasonal, and diurnal variation. Applied to nine solar cell types, the resulting divergence in solar cell efficiencies illustrates that a single spectrum is insufficient for comparisons of cells with different spectral responses. Cells with two or more junctions tend to have efficiencies below that under the standard spectrum. Silicon exhibits the least spectral sensitivity: relative weekly site variation ranges from 1% in Lima, Peru to 14% in Edmonton, Canada.

As the SOPHIA round robin aims for comparing different power rating methods, all partners agreed to use the same measurement guideline. This guideline considers the module alignment, the data requirement and the duration of data collection. Three methods to calculate the rated power from measurement data based on regression, averaging or translation are already evaluated using data of the first four partners. Initial results show maximum deviations in the rated power output between the test labs of less than about four per cent for the investigated rating methods.

As the SOPHIA round robin aims for comparing different power rating methods, all partners agreed to use the same measurement guideline. This guideline considers the module alignment, the data requirement and the duration of data collection. Three methods to calculate the rated power from measurement data based on regression, averaging or translation are already evaluated using data of the first four partners. Initial results show maximum deviations in the rated power output between the test labs of less than about four per cent for the investigated rating methods.

The results of three CPV module round robins are presented. Ten test labs around the world participated to the round robins in total. Each round robin used a different CPV module technology (Daido Steel, Soitec, Suncore). The data gathered at the test labs was used to test CSOC power rating procedures as basis for the IEC draft standard 62670-3. The deviation between the minimum and the maximum power output rated at the test labs was in average 4.4 % with a standard deviation of 1.8 %(abs). This underlines that power ratings or CPV modules are reliable and reproducible.

In recent years, satellite-based solar radiation data resolved in spectral bands have become available. This has for the first time made it possible to produce maps of the geographical variation in the solar spectrum. It also makes it possible to estimate the influence of these variations on the performance of photovoltaic (PV) modules. Here, we present a study showing the magnitude of the spectral influence on PV performance over Europe and Africa. The method has been validated using measurements of a CdTe module in Ispra, Italy, showing that the method predicts the spectral influence to within ±2% on a monthly basis and 0.1% over a 19-month period. Application of the method to measured spectral responses of crystalline silicon, CdTe and single-junction amorphous silicon (a-Si) modules shows that the spectral effect is smallest over desert areas for all module types, higher in temperate Europe and highest in tropical Africa, where CdTe modules would be expected to yield +6% and single- junction a-Si modules up to +10% more energy due to spectral effects. In contrast, the effect for crystalline silicon modules is less than ±1% in nearly all of Africa and Southern Europe, rising to +1% or +2% in Northern Europe.

The operating efficiencies of multijunction photovoltaic (PV) cells are sensitive to changes in the spectral distribution of solar irradiance. Previous studies suggest that optimizing a cell's spectral response can improve energy yields. To examine how this affects their performance in the field, two sets of triple-junction photovoltaic cells with different spectral responses are being characterized side-by-side outdoors in Nicosia, Cyprus. High-resolution measurements of the solar spectrum are also being recorded at this location, allowing a detailed examination of the cell performances under varying spectral conditions. Using spectral matching ratios to analyze the data has indicated that daily changes in the fill factors of the cells can be attributed to their spectral responses. However, average performance ratios over the period of testing are similar for the two cell types. An in-depth analysis reveals that this is due to a combination of both the spectral responses and the spectral resource at the test site, where both cells operate close to their optimum. This indicates that customizing the spectral response of a cell may only be advantageous for applications under an extreme spectral resource distribution.