Energy Yield Calculations Research Articles

Assessing the accuracy of two steady‐state temperature models for onboard passenger vehicle photovoltaics applications

AbstractWe assess the accuracy of two steady‐state temperature models, namely, Ross and Faiman, in the context of photovoltaics (PV) systems integrated in vehicles. Therefore, we present an analysis of irradiance and temperature data monitored on a PV system on top of a vehicle. Next, we have modeled PV cell temperatures in this PV system, representing onboard vehicle PV systems using the Ross and Faiman model. These models could predict temperatures with a coefficient of determination (R2) in the range of 0.61–0.88 for the Ross model and 0.63–0.93 for the Faiman model. It was observed that the Ross and Faiman model have high errors when instantaneous data are used but become more accurate when averaged to timesteps of greater than 1000–1500 s. The Faiman model's instantaneous response was independent of the variations in the weather conditions, especially wind speed, due to a lack of thermal capacitance term in the model. This study found that the power and energy yield calculations were minimally affected by the errors in temperature predictions. However, a transient model, which includes the thermal mass of the vehicle and PV modules, is necessary for an accurate instantaneous temperature prediction of PV modules in vehicle‐integrated (VIPV) applications.

Evaluating wind-farm power generation using a new direct integration of axisymmetric turbine wake

Engineering wake models enable fast calculation of wind-farm power generation including wake-turbine interactions, which is critical for annual energy yield calculations and for farm optimisation either at the design phase or during operation. The operating point of a turbine is determined based on its rotor-averaged wind speed, which is impacted by upstream wakes. The rotor-averaged deficit is typically calculated numerically by using a set of averaging points across the rotor disk, for which a Gaussian shape function is commonly evaluated. This numerical approach can have uncertainty based on the distribution of the averaging points. Also, a large number of averaging points can increase computational cost, which is detrimental for studies that rely on many individual calculations of farm power generation, e.g. layout optimisation. To avoid these drawbacks, we present a novel analytical solution to the circular-disk integration of a two-dimensional axisymmetric Gaussian function depicting upstream wakes for an arbitrary lateral offset between the rotor and the wake source. The analytical expression is compared against numerical averaging of an upstream wake, and is applied to the Horns Rev 1 wind farm showing excellent accuracy. Wind-farm layout optimisation models, especially methods based on gradient-descent optimisation, can benefit from the presented expression significantly, as this provides an analytically differentiable formulation for the rotor-averaged wind speed.

Machine learning for predicting offshore vertical wind profiles

The accurate characterization of the vertical wind profile over the sea that covers the rotor swept area of modern wind turbines is a key challenge for wind energy yield calculations. Since offshore wind measurements are scarce, early-phase projects tend to use numerical model outputs before planning a dedicated measurement campaign. This study aims to develop and validate a machine-learning model that can assimilate wind parameters measured at the first level of the meteorological masts as input and provide a wind speed profile covering the rotor swept area of modern turbines that is more accurate than numerical weather prediction models. The methodology is based on a random forest model implemented in the python package Scikit-Learn. Three offshore sites in the North Sea have been selected for this study, namely FINO3, IJmuiden and Nordsee Ost’s (NSO) met mast, which are 100 to 350 km apart. Each site has an instrumented 100-m meteorological mast along with a Doppler wind lidar measuring up to 300 m. The baseline selected for comparison was the Weather Research and Forecast (WRF) model. To assess the accuracy of the random forest model two models were trained at IJmuiden and FINO3 and tested at all three locations. Hence, we examine the model performance at the site of training, the so-called same site approach, as well as new sites, the so-called round robin approach. The same site approach quantifies the model consistency, while the round robin shows the degree of spatial robustness. The results show that the model is consistent, where the model trained and tested at FINO3 showed a mean absolute error (MAE) reduction of 68% compared to WRF. This model is also robust, when applied at IJmuiden, 350 km away with a MAE of 1.2 m/s, 8% improved compared to WRF outputs. This study therefore shows the potential to implement machine-learning methods in the prediction of vertical wind speed profiles over the sea. One potential application for the presented methodology is the extension of wind profiles measured by floating lidar systems to higher heights, where current wind lidar products have low availability and higher associated uncertainties, when measuring at a higher height.

Assessment of Wind Speed Statistics in Samaria Region and Potential Energy Production

Statistical characteristics of the wind speed in the Samaria region of Israel have been analyzed by processing 11 years of wind data provided by the Israeli Meteorological Service, recorded at a 10 m height above the ground. The cumulative mean wind speed at a measurement height was shown to be 4.53 m/s with a standard deviation of 2.32 m/s. The prevailing wind direction was shown to be characterized by a cumulative mean azimuth of 226° with a standard deviation of 79.76°. The results were extrapolated to a 70 m height in order to estimate wind characteristics at the hub height of a medium-scale wind turbine. Moreover, Weibull distribution parameters were calculated annually, monthly, and seasonally, demonstrating a good match with histogram-based statistical representations. The shape parameter of the Weibull distribution was shown to reside within a narrow range of 1.93 to 2.15, allowing us to assume a Rayleigh distribution, thus simplifying wind turbine energy yield calculations. The novelty of the current paper is related to gathering wind statistics for a certain area (Samaria), and we are not aware of any published statistics regarding wind velocity and direction in this area. These data may be interesting for potential regional wind energy development in which the obtained Weibull distribution could be used in calculations for the expected power generation of particular turbines with a known power dependence on velocity. We have given an example of these calculations for three different types of turbines and obtained their yield in terms of electric power and economic value. We also point out that the fact that realistic wind velocity statistics can be described well by an analytic formula (Weibull distribution) is not trivial, and in fact, the fit may have been poor.

DBD를 이용한 미세플라스틱 분해 시 처리시간에 따른 방전특성 변화 연구

Today, as plastic production has increased worldwide, the problem of microplastics exposed to the natural environment has emerged. Dielectric barrier discharge(DBD) is emerging as a new way to solve the microplastic problem. However, the majority of research is focused on removal efficiency and chemical changes on the surface, with a little study on electrical discharge characteristics. Therefore, in this study, the change in discharge characteristics according to the treatment time during microplastic treatment using DBD was analyzed through the Lissajous curve. As a result of the experiment, as the treatment time increased, the power consumption decreased by 25.59% when treatment for 120 minutes due to changes in charge amount, discharge initiation voltage, and capacitance. The results of this study will provide useful data for future microplastic degradation studies and energy yield calculations using DBD.

Developing an energy rating for bifacial photovoltaic modules

AbstractThe photovoltaic (PV) module energy rating standard series IEC 61853 does not cover bifacial PV modules. However, the market share of bifacial PV modules has dramatically increased in recent years and is projected to grow. This work demonstrates how Parts 3 and 4 of the IEC 61853 standard could be extended to bifacial modules. First, we develop an irradiance model that uses the data already given in the standard IEC 61853‐4 to calculate the irradiance on the rear side of the module. Second, we propose a way to extend the energy yield calculation algorithm IEC 61853‐3 to include bifacial modules and make it available to the PV community. This rear irradiance and bifacial energy yield calculation procedure is tested using real outdoor measurements for a nine‐month period with a root mean square difference between measured and simulated energy yield of 4.65%. To conclude, we investigate the impact of different climates and normalization on the bifacial module energy rating results.

Degradation of diclofenac and 4-chlorobenzoic acid in aqueous solution by cold atmospheric plasma source

In this study, cold atmospheric plasma (CAP) was explored as a novel advanced oxidation process (AOP) for water decontamination. Samples with high concentration aqueous solutions of Diclofenac sodium (DCF) and 4-Chlorobenzoic acid (pCBA) were treated by plasma systems. Atmospheric pressure plasma jets (APPJs) with a 1 pin-electrode and multi-needle electrodes (3 pins) configurations were used. The plasma generated using argon as working gas was touching a stationary liquid surface in the case of pin electrode-APPJ while for multi-needle electrodes-APPJ the liquid sample was flowing during treatment. In both configurations, a commercial RF power supply was used for plasma ignition. Measurement of electrical signals enabled precise determination of power delivered from the plasma to the sample. The optical emission spectroscopy (OES) of plasma confirmed the appearance of excited reactive species in the plasma, such as hydroxyl radicals and atomic oxygen which are considered to be key reactive species in AOPs for the degradation of organic pollutants. Treatments were conducted with two different volumes (5 mL and 250 mL) of contaminated water samples. The data acquired allowed calculation of degradation efficiency and energy yield for both plasma sources. When treated with pin-APPJ, almost complete degradation of 5 mL DCF occurred in 1 min with the initial concentration of 25 mg/L and 50 mg/L, whereas 5 mL pCBA almost degraded in 10 min at the initial concentration of 25 mg/L and 40 mg/L. The treatment results with multi-needle electrodes system confirmed that DCF almost completely degraded in 30 min and pCBA degraded about 24 % in 50 min. The maximum calculated energy yield for 50 % removal was 6465 mg/kWh after treatment of 250 mL of DCF aqueous solution utilizing the plasma recirculation technique. The measurements also provided an insight to the kinetics of DCF and pCBA degradation. Degradation products and pathways for DCF were determined using LC-MS measurements.

Low‐cost outdoor spectral irradiances determination and its application on Concentrator Photovoltaic module power rating and energy yield calculation

AbstractIn this work, a method to calculate the aerosol content in the atmosphere and the prevailing spectral irradiance of the sunlight is introduced. This method does not aim for low measurement uncertainty but for cost effectiveness and does not require sophisticated equipment. The bases of the method are the clear sky direct normal irradiance (DNI) and a look‐up table calculated with the software tool SMARTS2. The ratio of clear sky DNI to the prevailing DNI in combination with the look‐up table allows the determination of aerosol optical depth (AOD), spectral matching ratios (SMR), and spectral irradiances. Besides the prevailing DNI, the following ambient condition parameters are required: Air pressure, relative humidity, and ambient temperature. This means a weather station and a pyrheliometer are sufficient for the determination of the prevailing spectral irradiance. Obviously, this method cannot guarantee the same accuracy as conventional spectral irradiance measurement methods (e.g., using a spectroradiometer). However, in this work, we demonstrate the potential of this new method as a fall‐back strategy for missing spectral irradiance data. This method is worth using when (C)PV module power output data needs to be evaluated in dependence of the composition of the spectral irradiance, but no regular spectral irradiance data are available. In this paper, the AOD and SMR values determined with the introduced method are compared to measurement data with common measurement devices demonstrating a satisfying agreement. The spectral irradiances calculated with this method are successfully tested for using as the basis for energy yield calculations and for the determination of the CPV module power output at Concentrator Standard Conditions according to IEC 62670‐1.

Revealing the output power potential of bifacial monolithic all-perovskite tandem solar cells

Bifacial monolithic all-perovskite tandem solar cells have the promise of delivering higher output power density by inheriting the advantages of both tandem and bifacial architectures simultaneously. Herein, we demonstrate, for the first time, the bifacial monolithic all-perovskite tandem solar cells and reveal their output power potential. The bifacial tandems are realized by replacing the rear metal electrodes of monofacial tandems with transparent conduction oxide electrodes. Bandgap engineering is deployed to achieve current matching under various rear illumination conditions. The bifacial tandems show a high output power density of 28.51 mW cm−2 under a realistic rear illumination (30 mW cm− 2). Further energy yield calculation shows substantial energy yield gain for bifacial tandems compared with the monofacial tandems under various ground albedo for different climatic conditions. This work provides a new device architecture for higher output power for all-perovskite tandem solar cells under real-world conditions.

Microsecond Discharge Produced in Aqueous Solution for Pollutant Cr(VI) Reduction

This paper presents a detailed analysis of underwater electrical discharge parameters in the treatment of chromium (VI) used as a model pollutant to analyze the reduction process by plasma liquid interaction (PLI). Pin-to-pin microsecond discharges were performed in an aqueous Cr(VI) solution and the processes were characterized using electrical measurements, optical imaging and UV-Vis absorption measurements for [Cr(VI)] estimation. For the first time, the total reduction of Cr(VI) was successfully achieved by PLI process and a maximum energy yield of 4.7 × 10−4 g/kJ was obtained. Parametric studies on electrode geometry, applied voltage, electrodes gap and pulse duration are presented in detail. Finally, an analysis of the process is proposed by comparing our results of the energy yield calculation based on the injected energy with those of the literature and by providing an estimation of the global energy efficiency of the process.

Towards market commercialization: Lifecycle economic and environmental evaluation of scalable perovskite solar cells

AbstractMany economic and environmental studies on novel perovskite solar cells (PSCs), published ex post the development stage to investigate the market competitiveness, have focused on laboratory‐scale PSC architectures that are not amenable for upscaling. In this paper, we evaluate the market potential and environmental sustainability of a scalable carbon‐electrode‐based PSC by benchmarking it to the market dominating c‐Si photovoltaics and CIGS thin film photovoltaics. The analysis covers the PSCs full lifecycle, at the module and system levels (residential and utility scale), and is based on realistic annual energy output data derived from energy yield calculations. We find that this PSC can produce electricity at low cost (3–6 €cents/kWh), with lowest energy payback (0.6–0.8 years) and greenhouse gas emissions (15–25g CO2 eq./kWh) compared with grid‐connected PV market alternatives, assuming 25years of lifetime, expected PV system cost reductions, and PSC module recycling and refurbishment.

Model‐Chain Validation for Estimating the Energy Yield of Bifacial Perovskite/Silicon Tandem Solar Cells

The power conversion efficiency of conventional silicon solar cells approaches its theoretical limit. Bifacial operation and the perovskite/silicon tandem device architecture are promising approaches for increasing the energy yield of photovoltaic modules. Here, an energy yield calculation tool for (bifacial) perovskite/silicon tandem solar cells is presented. It uses a chain of models for irradiance, optical absorption, and temperature‐dependent electrical performance. Each step is validated with irradiance and performance data from a rooftop installation with mono‐ and bifacial silicon solar cells in Jerusalem, Israel. Selecting the data for two days (one in summer, one in winter) and considering the high‐reflective ground of this particular installation (albedo 60%) a 20% increased energy yield for a bifacial module with respect to a monofacial module is modeled. This result matches well with experimental data. When “upgrading” the silicon solar cell to a perovskite/silicon tandem solar cell, the case study predicts up to 40% additional energy yield. Combining the concepts of bifacial solar operation and perovskite/silicon tandem solar cells results in up to 60% increased energy with a high albedo ground, and is therefore a promising approach to further decrease the levelized cost of electricity for photovoltaic electricity generation.

LES verification of HAWC2Farm aeroelastic wind farm simulations with wake steering and load analysis

Wind farm simulation tools are used for a multitude of purposes, including energy yield calculations, wind farm control optimization, layout optimization, structural load analysis, and many more. However, the vast majority of farm software either fails to capture the dynamic nature of both the flow and the turbine structural response or demands a high computational cost such as large-eddy simulations (LES). In this study, we present a new mid-fidelity aeroelastic wind farm simulation software, HAWC2Farm, which can perform dynamic wind farm computations at the same temporal and spatial resolution as LES using a fraction of the computational resources. Wind farm simulations are performed with wake steering, and statistics are verified with results from LES performed using Ellipsys3D.

A Comparative Study of Wind Characteristics Between South-Western and South-Eastern Thailand Using Different Wind Turbine Models

Globally, wind energy has proven to be one of the most sustainable sources of energy. Wind energy assessment plays a critical role on determining installation of wind turbines worldwide. This work presents the technical evaluation of wind energy potential using three available wind turbine models for prospective onshore wind farm in the southern Thailand at Krabi and Songkhla sites. Ten-minute interval wind data over a period of 3 to 4 years obtained from Weather Observing Station is utilized to observe the diurnal and monthly wind speed, as well as frequency distribution. WAsP program is applied for energy yield calculations and wind resource maps. Our results reveal that Krabi and Songkhla has the highest mean wind speed of 4.39 m/s in December and 3.91 m/s in February, respectively. The prevailing wind direction in Krabi and Songkhla are north-east and south-east, respectively. WAsP analyses show that the total net AEP for Krabi is 7163.782 MWh, 7762 MWh and 12731 MWh using 275 kW, 300 kW and 500 kW wind turbine models, respectively. Similarly, the total net AEP for Songkhla is 7116.63 MWh, 7775.245 MWh and 12390 MWh using 275 kW, 300 kW and 500 kW wind turbine models, respectively. The total capacity factor for Songkhla and Krabi is 29.1% and 28.3%, respectively. Our results indicate that Enercon E-40/5.40 500 kW wind turbine model produces the highest total gross AEP and total net AEP for Krabi and Songkhla sites. Besides, the Vergnet GEV MP-C 275 kW turbine model shows slightly higher capacity factor in case of both sites. The findings of this study reflect that small to medium size wind turbines can be utilized to generate electricity at the sites.

Energy yield of perovskite solar cells: Influence of location, orientation, and external light management

Accurate forecasting of yearly energy yield of photovoltaic devices under realistic operating conditions is key for numerous practical applications related to further evolution of photovoltaics. In this work we present development and validation of an energy yield model applied to planar perovskite solar cells. The model is based on the combination of advanced optical modelling and extensive opto-electrical characterization and takes the geographical location and the orientation of the device into account. Using the model, we first perform a detailed sensitivity analysis and indicate the key parameters and their interdependencies that most significantly affect the calculated energy yield values. We show that the results are dominated (within 4% of the final value) by the solar irradiance dependency of the short-circuit current density, and further by the temperature dependency of the open-circuit voltage and the fill factor, whereas the irradiance dependency of the open-circuit voltage and the fill factor are mutually compensated. In the second part of the paper, we investigate how the energy yield of the device is affected by the application of external light management foils. Different texture morphologies, geographical locations, and device orientations are included in the investigation. The results show that even under realistic operating conditions, the overall trends of the light management efficiency of textured foils are not that different from those observed under standard test conditions; the highest energy yield gains in the order of 7–11% are obtained by the tetrahedral texture which is indicated as optimal in all studied cases. • EY forecasting crucial for LCOE estimation, degradation monitoring, and device optimization. • J SC under realistic conditions can be simulatend using advanced optical modelling. • V OC and FF under realistic conditions can be obtained through extensive electrical characterization. • External light management foils provide significant EY boosts under realistic outdoor conditions; tetrahedral micro texture indicated as the optimal in all studied cases. • Similar trends observed as under STC conditions, with similar achievable relative gains.

Amorphous CdO‐In2O3 Electrode for Perovskite‐Based Bifacial and Tandem Photovoltaic Technologies with High Energy Production

Energy production of perovskite‐based photovoltaic (PV) technology can be increased not only by improving device efficiency of perovskite solar cells (PVSCs) but also by innovative concepts such as bifacial and tandem configurations which require low‐damage and highly transparent top electrodes. Herein, an amorphous CdO‐In2O3 alloy film with high transparency and low resistivity and its application in a bifacial PVSC and a perovskite/Si 4T tandem solar cell are reported. Due to the high optical transmittance, the CdO‐In2O3‐based PVSC shows a high bifaciality factor of 84.0%, and the CdO‐In2O3‐based perovskite/Si 4T tandem solar cell achieves a champion power conversion efficiency of 25.12%, much higher than the indium tin oxide based tandem cell. Finally, a yearly energy yield calculation and levelized cost of energy (LCOE) analysis for these PV technologies (together with Si single‐junction solar cells as a reference) in Singapore, Australia, and Germany are conducted. The results demonstrate the potential of CdO‐In2O3‐based perovskite PV technologies, yet more efforts are still required to further reduce the manufacturing cost to achieve competitive LCOE values in countries with relatively low PV installation cost.

Improving the accuracy of energy yield calculations of tandem solar cell‐based CPV‐modules

AbstractEnergy yield calculations for CPV modules that use tandem solar cell technology have been performed and analysed in this work. Two BSQ D280 CPV modules were used as specimen: one located in Freiburg, Germany, and one in Greater Noida, India. The current–voltage curves of both modules were measured for several months together with the prevailing ambient conditions. The energy yield in the respective measurement periods were calculated using the software PVsyst. It has been found that the energy yield modelled with PVsyst has a good agreement with the one measured in Freiburg, but deviates by 10% from the one measured in Greater Noida. The reason is most likely the high aerosol content in Greater Noida and thus the non‐appropriate consideration of spectral irradiance impact by PVsyst, which uses air mass and DNI as the only atmospherical parameters. The accuracy of the PVsyst calculation has been strongly improved in this work by using SMR corrected DNI values as input for the PVsyst calculation. In this manner, the impact of spectral irradiance variation on (C)PV module power output can be considered in energy yield calculations by PVsyst. The deviation of the calculated and measured energy yield could be reduced to below 1%.

Perovskite/Silicon Tandem Solar Cells: Effect of Luminescent Coupling and Bifaciality

The power conversion efficiency of the market‐dominating silicon photovoltaics approaches its theoretical limit. Bifacial solar operation with harvesting additional light impinging on the module back and the perovskite/silicon tandem device architecture are among the most promising approaches for further increasing the energy yield from a limited area. Herein, the energy output of perovskite/silicon tandem solar cells in monofacial and bifacial operation is calculated, for the first time considering luminescent coupling (LC) between two sub‐cells. For energy yield calculations, idealized solar cells are studied at both standard testing as well as realistic weather conditions in combination with a detailed illumination model for periodic solar panel arrays. Typical experimental photoluminescent quantum yield values reveal that more than 50% of excess electron–hole pairs in the perovskite top cell can be utilized by the silicon bottom cell by means of LC. As a result, LC strongly relaxes the constraints on the top‐cell bandgap in monolithic tandem devices. In combination with bifacial operation, the optimum perovskite bandgap shifts from 1.71 eV to the range 1.60–1.65 eV, where already high‐quality perovskite materials exist. The results are very important for developing optimal perovskite materials for tandem solar cells.

Efficient bifacial monolithic perovskite/silicon tandem solar cells via bandgap engineering

Bifacial monolithic perovskite/silicon tandem solar cells exploit albedo—the diffuse reflected light from the environment—to increase their performance above that of monofacial perovskite/silicon tandems. Here we report bifacial tandems with certified power conversion efficiencies >25% under monofacial AM1.5G 1 sun illumination that reach power-generation densities as high as ~26 mW cm–2 under outdoor testing. We investigated the perovskite bandgap required to attain optimized current matching under a variety of realistic illumination and albedo conditions. We then compared the properties of these bifacial tandems exposed to different albedos and provide energy yield calculations for two locations with different environmental conditions. Finally, we present a comparison of outdoor test fields of monofacial and bifacial perovskite/silicon tandems to demonstrate the added value of tandem bifaciality for locations with albedos of practical relevance. Bifacial solar cells can outperform monofacial cells by exploiting sunlight reflected off the ground surface. De Bastiani et al. show that bifacial perovskite/silicon tandem with an optimized bandgap can deliver a power density of 26 mW cm–2 and compare its performance to monofacial cells under outdoor conditions.

Degradation of aqueous atrazine using persulfate activated by electrochemical plasma coupling with microbubbles: removal mechanisms and potential applications

Persulfate (PS) activated by dielectric barrier discharge (DBD) integrated with microbubbles (MBs) was designed to decompose atrazine (ATZ) from aqueous solutions. The degradation efficiency reached 89% at a discharge power of 85W, a PS concentration of 1mM, and a air flow rate of 30mL/min after 75min treatment. Heat caused by DBD favoured ATZ removal. Besides, the effect of PS dosage, discharge power and initial pH values on ATZ removal was evaluated. The calculated energy yield revealed that it was economical and promising to treat 1L of ATZ-wastewaters. The existence of SO42−, Cl−, CO32− and HCO3− lead to negative effects, while positive effect was observed when the presence of MBs and humic acid. The identification results of radicals and degradation intermediates suggested that multiple synergistic effects (such as heat, eaq− and H•) activated PS, and 1O2/reactive nitrogen species, •OH and SO4−• with contributions of 18%, 26%, and 29%, were main species attacking ATZ. ATZ degradation pathways including olefination, alkylic-oxidation, dealkylation, and dechlorination were proposed. An environment-friendly and a novel method for enhancing the PS-activation and ATZ-decomposition was provided, which fully utilised the electric-chemical conversion of DBD and high mass transfer efficiency of MBs.