Power Degradation Rate Research Articles

An optimal control method considering degradation and economy based on mutual learn salp swarm algorithm of an islanded zero‐carbon DC microgrid

AbstractDue to the energy storage lifetime effects of the power allocation, there is a large space to improve the economy of the electric‐hydrogen hybrid DC microgrid. This paper provides an optimal control method based on the mutual learn salp swarm algorithm (MLSSA) in real‐time, which aims to enhance the economy and extend the system's service life. In order to realize the economic operation, operation cost and degradation cost of battery and hydrogen system are considered as the objective function first. Then, salp swarm algorithm based on mutual learn strategy is introduced to obtain optimal economy power allocation results in real‐time with higher convergence speed and increased accuracy. In addition, the proposed method also maintains the battery state of charge (SOC) and state of hydrogen charge (SOHC) within a proper range to guarantee the stable operation of the system. Finally, the results including power results, cost analysis and degradation rate analysis of the MATLAB/Simulink show that the proposed method is more economically beneficial than the non‐considering degradation cost strategy.

Synthesis, characterization and performance evaluation of a novel flower-like Zn[sbnd]Zr MOF/FeWO4/BiOBr/Ti photoanode with type II heterojunction and visible light response

The performance of a photocatalytic fuel cell (PFC) depends on its photoelectrode. In this work, a novel three-dimensional flower-like hierarchical photoanode ZnZr MOF/FeWO4/BiOBr/Ti was synthesized, characterized and applied in PFC to degrade rhodamine B and generate electricity simultaneously. The characterization results of XRD, SEM, EDS, FI-IR, DRS, and XPS show that the photoanode was successfully prepared. The loading of FeWO4 and ZnZr MOF widened the nanosheet spacing of BiOBr, which enhanced the light absorption intensity, broadened the light absorption band edge from 467.6 nm to 490.2 nm, and increased the photocurrent density from 0.0149 mA/cm2 to 0.156 mA/cm2. The maximum photocurrent density, maximum power density, degradation rate, and FF of the PFC with the prepared photoanode were respectively 0.256 mA·cm−2, 22.65 μW·cm−290.48 % (1 h), and 0.216, which were far higher than those of PFCs with mono and binary photoanodes. The strong photocatalytic performance of the photoanode is attributed to the type II heterojunction formed between BiOBr and FeWO4, which helps to separate electron-hole pairs. The main reactive materials responsible for degrading rhodamine B are h+ and ·O2-. This research provides a new idea for developing an efficient visible light response photoanode.

Analysis of Microwave Effects on the MnO2-Catalyzed Toluene Oxidation Pathway

Microwave radiation has become an effective catalytic combustion method, especially in the degradation of volatile organic compounds (VOCs) such as toluene using catalysts like MnO2. In this study, a spine waveguide microwave reactor was designed to investigate the influence of different microwave processing conditions on the degradation of toluene catalyzed by MnO2. An experimental system for microwave-assisted catalytic degradation of toluene was established to explore the relationship between microwave power, catalyst conductivity, and toluene degradation rate. The results showed that the efficiency of MnO2 catalyzing toluene degradation had a nonlinear relationship with microwave power, first increasing to a peak and then decreasing. Additionally, the experiment found that the degradation rate of toluene was positively correlated with the conductivity of MnO2. Subsequent characterization analyses using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) further verified the changes in the microstructure and properties of MnO2 under microwave heating. The characterization results showed that with the increase in microwave power, the relative content of Mn3+ on the surface of MnO2 increased, and the relative content of adsorbed oxygen also increased accordingly. At a microwave power of 100 W, the treated MnO2 displayed the optimal ratio of manganese oxidation state and oxide, both close to 1:1, which was more conducive to the degradation of toluene. Based on these findings, this study hypothesized that the microwave-enhanced catalytic degradation of toluene by MnO2 may be attributed to changes in the surface electron transfer kinetics of MnO2, providing new insights into the field of microwave-enhanced catalysis.

Predictive analysis of power degradation rate in solar PV systems emphasizing hot spots and visual effects-based failure modes

A definite and exclusive long-term PV degradation projection is required to reduce financial vulnerability in the solar photovoltaic plant-based energy transition markets. So, in this paper beside a traditional linear rate approach, a non-linear design tool for quantifying long-term failure mode-based power degradation rate (Rd), is proposed. An on-field experimental investigation incorporating visual effects-based Solar I–V characterization and thermal imaging for a duration of 1 year (February 2022 to January 2023) is carried out on a realistic solar PV system exposed to field conditions for 5–6 years. The experimentally evaluated Rd is 7.7 %/year. Two non-linear failure mode-based Rd models employing machine learning approaches, with differences in inputs are developed and are proven economically useable against the reported assessment techniques. The root mean square error (RMSE) for model 1 and model 2 during testing is 0.0019 and 0.0020 respectively (LSTM based approach) whereas testing error for model 1 and model 2 using back propagation based approach is 0.00182 and 0.00132 respectively. The proposed tool is also validated for a realistic PV plant in Telangana. A closeness of prediction against the actual of 9.0 % is observed for model 1 during validation, whereas the same for model 2 is 9.6 %.

Influence of Passivation and Solar Cell Configuration on the Electrical Parameter Degradation of Photovoltaic Modules

This article analyses and compares the influence of p-type Cz-Si solar cells produced with and without Al-BSF and silicon oxide passivation on the degradation of the electrical parameters of PV modules, after 77 months under operating conditions in a PV system. Solar cells were manufactured at a pilot plant-scale facility, and 32 PV modules with silicon oxide passivated emitter and Al-BSF solar cells were assembled. The other group was composed of 28 PV modules produced with n+pn+ solar cells. The I–V curves of the PV modules were measured under standard test conditions before and after 77 months of exposure. In both groups, the short-circuit current presented higher degradation, and the open-circuit voltage showed low reduction. However, the degradation of these electrical parameters was lower in PV modules assembled with a passivated emitter and Al-BSF solar cells. Consequently, the power degradation rate of PV modules with passivated emitter n+pp+ and n+pn+ solar cells was 0.29% and 0.66% per year, respectively. The milky pattern was observed at the edge of all solar cells and was related to titanium dioxide antireflective coating modification and laser isolation processing.

Performance degradation and reliability evaluation of crystalline silicon photovoltaic modules without and with considering measurement reproducibility: A case study in desert area

In this paper, performance degradation and reliability evaluation of crystalline silicon photovoltaic modules deployed in desert climate was investigated based on the more than 7-year tracking test. It is found that peak power standard deviation first increased with time, reaching the peak when modules operated for 3 years, and then continuously decreased. Then, relationship among power warranty, power degradation rate and tolerance on maximum power is revealed for the first time. If 1% of module failures during warranty period is allowable, the 30-year warranty can be realized when degradation rate is 0.4–0.6 %/year with tolerance 0 ∼ +5% and 0 ∼ +3%, or degradation rate is 0.5 %/year with tolerance ±5% and ±3%, or degradation rate is 0.4 %/year with tolerance ±10%, ±5% and ±3%. Finally, reproducibility of power measurement is introduced for more accurately evaluating module performance degradation and reliability. Meanwhile, determination procedure of reproducibility for module electrical performance is systematically set forth. It is found that power warranty period can be prolonged if reproducibility is considered. The results obtained in this paper can provide new insights into performance degradation, reliability assessment and power warranty for fielded crystalline silicon solar modules.

Temperature profiles of field-aged photovoltaic modules affected by optical degradation

Moisture ingress into PV module in the presence of ultraviolet radiation, high temperature, and other environmental stressors can affect the optical integrity of the PV module. Optical degradation can take the form of delamination, discolouration of encapsulant, metal grids corrosion, and trapped moisture or chemical species. This can influence the photon absorption and current transport properties in the PV module bulk, which can affect the module operating temperature. In the present work, the relationship between optical degradation and temperature sensitivity of 20-year-old multicrystalline silicon field-aged PV modules have been investigated. The selected PV modules were characterized using visual inspection, current-voltage (I–V) characterization, temperature coefficients profiling, current resistivity profiling, infrared (IR) thermal, ultraviolet fluorescence (UV–F), and electroluminescence (EL) imaging. PV modules affected by optical degradation show weak fluorescence and luminescence signal intensities. The average difference in cell temperature (ΔT) between the warmest and coldest cell for the PV modules investigated was found to be around 10 ± 2 °C and the average power degradation rate was approximately 0.8% per year. The underlying factor for the observed degradation is attributed to the degradation in the temperature coefficients of open circuit voltage (βVoc) and maximum power point voltage (βVmpp). The average temperature coefficient of efficiency (βηm) of the modules was found to be around −0.5%/°C. Finally, a temperature dependent resistivity method for extracting temperature coefficients from IR thermal data of PV modules has been proposed.

Operating strategy optimization by response surface analysis for durable operation of a heavy-duty fuel cell truck

A proton exchange membrane fuel cell (PEMFC) of heavy-duty truck is operated in very harsh conditions, but it requires more longevity than a passenger vehicle. Currently, the durability strategy of vehicular fuel cell is set up for passenger vehicles. This study is designed to establish durability strategy of heavy-duty fuel cell trucks by model based on response surface analysis. A physics-based model is developed to predict degradation of a PEMFC under truck operation mode. The model is then validated with 2000 h of 20-cell PEMFC stack experimental data operated under the truck operation mode, such as world harmonized vehicle cycle (WHVC) mode. Since the various operating variables are presented, a response surface method (RSM) selects the power output and degradation rate as object functions. Results show that operating temperature is the most significant variable, followed by inlet temperature of gases. As the operating temperature increases, the power output increases, but the degradation is accelerated. By contrast, increasing gas inlet temperature decreases power output and degradation rate. When the fuel cell truck is operated at high humidity, moderate cell temperatures, and moderate gas inlet temperatures, the power output is maximized with minimum voltage degradation. As determined by this study, the optimal operating conditions are anode and cathode relative humidity of 100%, a fuel cell temperature of 61 °C, and a gas inlet temperature of 57 °C.

Degradation analysis of polycrystalline silicon modules from different manufacturers under the same climatic conditions

Different kinds of photovoltaic modules from various manufacturers have entered the PV market. However, the long-term performance of these modules under outdoor conditions is uncertain. This study evaluated the degradation of polycrystalline silicon modules from 11 different manufacturers installed under the same climatic conditions in Kumasi, Ghana with the aim of predicting the long-term performance of the modules. Specifically, this study sought to: (i) analyse the power degradation rates of the modules and determine the correlation between the degradation and the age of the modules, (ii) determine the correlation between the power degradation and other electrical performance parameters of the modules, (iii) identify the modules with visual defects and compare their degradation rates with the modules without any visual defects, (iv) compare the degradations of PV modules from the same manufacturer installed under the same climatic conditions for the same number of years and (v) assess the installation and maintenance practices that could negatively affect the degradation of the modules. Forty-eight PV modules from 11 different manufacturers were sampled from 12 PV systems installed between 5 and 9 years. The methods used were visual inspection, observation, interviews, and current–voltage (I-V) tracings. The results revealed the mean power degradation rates of the modules between 0.79 and 1.67%/year, contingent on the manufacturer. The power degradation rate had no correlation with the age of the modules but the power degradation of all modules was mainly due to the degradation of short circuit current (Isc) of the modules. Light encapsulant discoloration, dark encapsulant discoloration, minor frames corrosion, and minor metallization discoloration were found on modules from four different manufacturers. However, the degradation of electrical performance parameters could not be solely attributed to these visual defects. Slight variations in degradations were observed for PV modules from the same manufacturer installed under the same climatic conditions for the same number of years. The installation and maintenance practices of the system owners were similar and unlikely to impact differently on the degradation of the modules from different manufacturers.

Evaluation of degradation energy productivity of photovoltaic installations in long-term case study

In the last twenty years, photovoltaic installations have become a popular form of renewable energy sources, both in Europe and around the world. One of the European pioneers in this field was Germany. Photovoltaic installations are inevitably associated with a decrease in productivity during operation years based on power degradation of photovoltaic cells. This article analyzes the decrease in energy productivity of installations over 16 years using the example of two rooftop photovoltaic installations and proposes a modified methodology for calculating the decreasing effect. The tested installations are located in the south-west of Germany, in the town of Sinsheim. The first installation, I-1, has a capacity of 37.8 kWp (Suntech panels, 150 Wp), and the second one, I-2, has a capacity of 18.48 kWp (Suntech panels, 165 Wp). In the first two years, the actual productivity calculated from the theoretical productivity estimated for the installation (modified Performance Ratio value) was 95.8% for I-1 and 96.8% for I-2. However, in the years 2020–2021 (the last two years of the installation's operation), the actual productivity calculated from the theoretical productivity estimated for the installation was 93.9% for I-1 and 93.8% for I-2. The reported yearly power degradation rate in the analyzed installations was 0.11%/year for I-1 and 0.2%/year for I-2, which is lower than in the literature examples.

Multi‐pronged degradation analysis of a photovoltaic power plant after 9.5 years of operation under hot desert climatic conditions

AbstractLong‐term reliability assessment of photovoltaic (PV) modules is key to ensuring the economic viability of PV systems. This paper presents a multi‐pronged performance degradation analysis of a 62.1 kWp solar PV power plant after 9.5 years of operation. For this purpose, various diagnosis techniques, namely, visual inspection, infrared thermography (IR), ultraviolet fluorescence (UVFL) and current‐voltage (I‐V) characterization, have been performed to evaluate the performance and degradation of the solar PV power plant. The visual characterization results show that the PV strings are affected by different mechanisms with different degrees of occurrences. The degradation mechanisms observed and the level of occurrence among the modules were found to be, encapsulant discolouration (100%), degraded frame adhesive (57%), degraded junction box adhesive (39%), snail trails (30%), burn marks (3%), cell cracks (2%) and delamination (0.4%). Although discolouration of the encapsulant was the most common possible degradation mechanism observed, the main causes of the power loss were snail trails and cracks in the PV cells. Furthermore, the IR thermography and UVFL analysis provided better understanding on snail trails phenomenon and crack mechanism on the affected PV modules. Besides imaging techniques, to assess the electrical performance of the system, we performed current‐voltage (I‐V) and power‐voltage (P‐V) characterization of the entire PV plant from which the degradation rates of the electrical parameters were determined. Our results show that the degradation rates for the maximum power and the fill factor are 0.84%/year and 0.66%/year, respectively, over the operating period of the installation. The estimated maximum power degradation rate for this installation could be considered as a realistic degradation rate for PV modules installed in harsh and hot desert climatic conditions. Additionally, our work has raised doubts about the validity of the warranties proposed by the manufacturers.

Aeolian dust distribution, elemental concentration, characteristics and its effects on the conversion efficiency of crystalline silicon solar cells

Exposure of PV modules to ambient environmental conditions like dust deposits, has some deleterious effects on peak power (Pmax) and overall conversion efficiency (η). This study investigates the effect of module height, tilt, and orientation on the rate of dust deposition on the surfaces of PV modules. Consequently, the effect of different dust categories on Pmax and η are investigated. North facing module surfaces are observed to exhibit higher deposition rates in southerly winds. A significant decrease in conversion efficiency of 1.30%, 1.74%, 4.05%, 2.74% and 1.38% after a fortnight are observed in modules installed in five randomly selected study sites. A higher decrease in efficiency on average after a fortnight is observed in sites having traces of anthropogenic particles on dust samples collected from the PV surfaces with minimal effects observed in sites having biogenic and geogenic particles. Abundance of anthropogenic dust particles coupled with mild tilt and leeward orientation led to a higher maximum power and efficiency degradation rate.

Degradation of Monocrystalline Silicon Photovoltaic Modules From a 10-Year-Old Rooftop System in Florida

A system of 180 monocrystalline aluminum back-surface field modules were installed in Cocoa, Florida, for 10 years. In total, 156 modules are characterized and compared to 3 controls. Power degradation rates vary between <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 0.14% to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 3.22% per year, with median and average rates of −0.92% and −1.05% per year, respectively. The losses are primarily resistive with minor optical and recombination loss contributions. Electroluminescence imaging shows a characteristic pattern, which is shown to be resistive in nature when compared to photoluminescence. Resistive losses are due to corrosion of the rear contact Ag/solder interface and, to a much lesser degree, gridline Ag oxidation. Moisture ingress through the backsheet is likely responsible for mediating corrosion. Optical losses are due mostly to a combination of antireflection coating degradation, minor encapsulant browning, and delamination. Minor front contact corrosion may contribute to recombination. This study expands upon previous work on this vintage of the module by examining a large sample set, comprehensive characterization including techniques not previously used on these modules, and a comparison between two other systems of different climates.

Correlating dust deposits with wind speeds and relative humidity to overall performance of crystalline silicon solar cells: An experimental study of Machakos County, Kenya

Solar Photovoltaics is one of the budding technologies widely acknowledged as a solution to energy poverty. This is due to its high reliability, long life and automatic operation at low maintenance requirements even though handicapped by its low conversion efficiency and high capital costs. This study investigates the influence of wind profiles, relative humidity and module siting on dust deposition on the surfaces of photovoltaic modules hence its overall performance in an outdoor setup. A significant decrease in short circuit current density (JSC), maximum current density (JMPP), and voltage at maximum power point (VMPP) due to dust deposits on the surface of the PV module are observed. The modules peak power (Pmax) degradation rate after a fortnight is observed to be higher (4.4 %) for sites experiencing a higher temperature coefficient (Tc) for VMPP as a consequence of temperature effects of soiling, lower wind speeds and a higher relative humidity. A lower deposition rate is observed in sites experiencing higher wind speeds and a higher module’s tilt angle thus experiencing a lower effect on the reduction of current and voltage parameters. Similarly, the site-specific average wind speeds were inadequate for complete particulate resuspension of small sized particles (less than 500μm) adhering to PV module surface. Therefore, dust accumulations on the surface of PV modules have significant deleterious effects on the current and voltage parameters.

Efficiency-Focused Maintenance Model to Recover the Performance of a Gas Turbine with Inlet Air Cooling and Affected by Fouling

Efficiency-Centered Maintenance (ECM) models are vital in the industry since they increase the overall efficiency of the system and the availability of assets, considerably reducing polluting emissions and operating costs. Because of this, it has been tried to quantify the potential of ECM models in improving power generation systems. This paper presents an ECM model to recover the performance of a gas turbine that has suffered performance degradation due to exposure to fouling and variations in the compressor inlet air temperature. A strategy has been designed and implemented in order to define and schedule activities that, economically and energetically justified, have restored the performance of a simple Brayton cycle power generation facility. The net power output and the Heat Rate have been the performance indicators selected for monitoring the energetic condition of the gas turbine. Similarly, the availability and the mean time between interventions have been maintenance indicators. The results indicate that net power and availability have increased by 5%, the Heat Rate has decreased by 2%, and the mean time between interventions has increased by 5.7 times. The power degradation rate has been reduced from 9% to 1%, ending with an annual degradation of 7.4%. With the results obtained, it has been confirmed that the ECM applied to power cycles increases the system's operational efficiency, reducing costs and polluting emissions.

Mid-life degradation evaluation of polycrystalline Si solar photovoltaic modules in a 100 kWp grid-tied system in east-central India

This study presents the mid-life degradation evaluation of a 100 kWp grid-tied solar photovoltaic (PV) power plant which is in the eleventh year of its operation. The field evaluation includes the visual inspections to identify the extent of degradation present in the PV modules, and the measurement of field current-voltage (I–V) data for maximum power deviation of the operational PV modules. Significant visual degradations were observed in many PV modules like encapsulant discoloration, snail tracks and cell cracks, burn marks on the surface of the PV module, shattering of front PV glass due to lightning strike, discoloration on metallization, corroded metal frame and hot spots. The PV module having heavy snail tracks, visible cracks and burn marks on the surface showed the highest power reduction of 95.9 W with respect to the reference module. The power degradation rate of the reference PV modules, which had no apparent visible degradation, over a period of ten years, was found to be varying between 0.16%/year to 1.72%/year. This study would be helpful in better understanding of the various types of degradations affecting the PV modules operating in the composite climate regions of east-central India.

Impact of the desert climate on the degradation of photovoltaic modules characteristics: a case study

ABSTRACT In this paper, an investigation study has been carried out to evaluate the photovoltaic module degradation, in a desert area of Algeria. In this view, a set of PV modules have been put into tests and assessment for more than 11 years. These modules were assembled into three PV generators composed of monocrystalline (mc-Si) and polycrystalline (pc-Si) PV modules. The I–V curve tracer, calibrated reference m-Si solar cell and Pt1000 temperature sensor tools were used to collect the data. Three degradation modes were examined namely: (i) the visual inspection characterized mainly by a discoloration of PV modules, (ii) I–V degradation characterized by an increase in the series resistance which corresponds to electrical losses in conductors and (iii) the degradation rate (DR) assessment. The main parameters affecting on PV system performance are the high temperatures and sandstorms that characterize desert regions. The results indicated that for monocrystalline and polycrystalline PV modules, the power degradation rates were 1.53% and 0.37% per year, respectively. This degradation rate was found to be 2.36% per year for modules with broken back-sheet and corroded junction box. The production situation of examined PV systems shown a decrease of about 9%, 13%, and 6.8% for PVG1, PVG2, and PVG3, respectively, throughout the operation period. In addition, cell discoloration was observed as the predominant mode of degradation mechanism in desert climatic conditions.

New model to study the outdoor degradation of thin–film photovoltaic modules

The performance of four thin-film photovoltaic modules is analyzed after an initial stabilization period and a subsequent outdoor exposition. The seasonal variations and the degradation rates of a single-junction hydrogenated amorphous silicon (a-Si:H) module, a tandem amorphous microcrystalline Silicon (a-Si/μc-Si) module, a heterostructure cadmium sulfide-cadmium telluride (CdS/CdTe) module and a copper indium gallium selenide (CIGS) are examined and correlated to spectral changes. The I–V curves have been measured every 5 min; the electrical parameters and parasitic resistances have been identified. By exploiting a number of experimental measurements acquired within a narrow interval of irradiance and cell temperature, a novel mathematical model has been developed and fitted: it considers a stationary seasonal variation component and a linear long-term degradation component. The results show annual power degradation rates of 4.0% for the a-Si:H module, 3.4% for the a-Si/μc-Si and 3.5% for the CdS/CdTe, whereas for the CIGS module the annual degradation is not significant, i.e. 0.2%.

Analysis of the degradation of amorphous silicon‐based modules after 11 years of exposure by means of IEC60891:2021 procedure 3

AbstractThe degradation of two amorphous silicon‐based photovoltaic (PV) modules, namely, of single junction amorphous silicon (a‐Si) and of micromorph tandem (a‐Si/ ‐Si), after 11 years of exposure in the south of Spain is analyzed. Their I‐V curves were measured outdoors to study the changes of the electrical parameters in the course of three different periods: during the initial days of exposure, during the first year, and in the subsequent 10‐year period. The translation of the curves to an identical set of operating conditions, which enables a meaningful comparison, was done by the different correction procedures described in the standard IEC60891:2021, including the procedure 3, which does not require the knowledge of module parameters, whose values are typically not available. The annual power degradation rates over the entire 11‐year period are 1.12% for the a‐Si module, which is 3.02% for the first year, and 0.98% for the a‐Si/ ‐Si, which is 2.29% for the initial year.

Performance of PV systems in Slovenia with the help of typical daily profiles and automatic detection of orientation and inclination angles

Operators of photovoltaic (PV) systems, especially the small ones, monitor only the produced energy output, since they are not equipped with a meteorological station, or there is none in the neighbourhood. When evaluating a large number of PV systems across a region or country, access to the data due to privacy restrictions is usually very limited. To resolve both aspects, we report on a methodology to evaluate the performance of photovoltaic systems where only produced energy data and rated power of the PV system are available and all other data, including orientation and inclination angles, and the exact location are missing. We developed a novel algorithm for automatic detection of orientation/inclination angles and used the recently developed Typical Daily Profiles (TDP) methodology for a fast and accurate evaluation of PV systems. TDPs are representative hourly profiles of the observed parameter (e.g., power, irradiance and temperature) on a monthly basis. For the PV system degradation rate extraction, year-to-year TDPs are used. The case study of 957 PV systems in Slovenia in the period 2015–2019 reveals an average PV system performance ratio exceeding 85% and an average PV system rated power degradation rate of −0.7% per year.