Output Power Degradation Research Articles

Optimizing PV Module Efficiency: Investigating the impact of Dry and Wet Dust on Solar Panel Output Power

Solar photovoltaic modules convert sunlight into electricity through the photoelectric effect. Dust accumulation on PV modules can significantly reduce their output electrical characteristics such as voltage, current, and power. The power reduction is attributed to the decrease in the amount of light reaching the solar cells due to the absorption and scattering of light by the dust layer. The magnitude of the power reduction depends on the amount and type of dust component of the solar panel. In this work, four dust components such as red soil, sand, wood power, and bird drooping are considered to test the PV performance. An indoor experimental setup is developed to test the dust impact on the PV modules using an artificial sun simulator. Experimental shows that the effect of dust accumulation on the voltage and current characteristics of solar panels is complex and depends on various factors. The percentage of degradation of output power is measured using dust under dry and wet conditions. Moreover, different amounts of dust such as 1gm, 3gm, 5gm, 7gm, and 9gm are considered for dry conditions, and 3gm and 5gm are considered for wet conditions. Bird drop causes a maximum degradation of 24.5% in dry conditions and it reduces by 17.2% in wet conditions. GUB JOURNAL OF SCIENCE AND ENGINEERING, Vol 10(1), 2023 P 68-74

High-performance and durable membrane electrode assemblies based on CeO2 and ePTFE double-reinforcement strategy for proton exchange membrane fuel cells operating at elevated temperatures

The membrane electrode assemblies (MEAs) play a decisive role in operating conditions and lifetime of fuel cell. In this study, MEAs that could work stably at elevated temperatures were prepared. With this method, a short-side chain perfluorosulfonic acid ionomer coating with CeO2 nanoparticles and two layers of expanded polytetrafluoroethylene reinforcement, to be used as a proton exchange membrane, was directly deposited between the cathode and anode gas diffusion electrodes, forming a double-reinforced integrated MEA. The effects of CeO2 doping amount on performance and other electrochemical properties of MEAs were systematically studied. Under the coupling effect of the water-retention and non-proton-conducting properties of CeO2, the 0.5 wt% CeO2-doped MEA (MEA-S0.5) had optimal performance above 100 °C and under low relative humidity (RH) conditions. At 120 °C and 30% RH, MEA-S0.5 exhibited peak power density of 0.460 W cm−2 (H2/air operation, 100 kPa), which was about 1.28 times that of MEA without CeO2 doping (MEA-S0). Furthermore, CeO2 effectively enhanced the durability of the MEA. Compared with MEA-S0, MEA-S0.5 did not exhibit significant degradation in output power, H2 crossover, or proton conductivity in the 100-h open-circuit voltage-holding test. This work paves the way for developing high-performance, durable MEAs that are suitable for elevated temperatures.

Long-term outdoor performance and degradation evaluation of CIS PV plant under the semi-arid climate of Benguerir Morocco

The effectiveness of a solar photovoltaic module relies on location related factors, including latitude, seasonal variations, irradiance levels, clearness index, and similar elements. In compliance with International Electrotechnical Commission (IEC) standards, performance and degradation assessment studies for photovoltaic (PV) technologies have been conducted in a variety of geographical areas with diverse climatic conditions in recent years. A comprehensive study of PV systems employing several technologies will provide some operators and stakeholders with statistically significant findings for assessing system performance. As a result, long-term and short-term performance and feasibility sur may provide information about the characterization of next-generation PV panels. The objective of this study is to perform an outdoor performance assessment and analysis of a 10.44 kWp grid-connected photovoltaic PV system comprised of Copper Indium Selenium (CIS) modules. This work will investigate how a CIS PV plant performs and degrades in Morocco’s semi-arid climate. The study is performed in the period between 2018 and 2021. The measured and estimated performance indicators are evaluated with the aim of assessing the technology’s adaptability and degradation; the methodology applied comprises performance evaluations of the PV system in accordance with IEC-61724 standard guidelines. After 6 years of outdoor exposure, the CIS system’s output power declined with a degradation rate of 3.13%/year obtained using linear regression. I–V curve measurements performed in real test conditions (RTC) determined that power output degradation reached −21.6%, which was more observable in short-circuit current and varies between −8.1% and −18.1% for individual modules.

Photovoltaic Module Fault Detection Based on Deep Learning Using Cloud Computing

The performance of photovoltaic modules (PVMs) degrades due to the occurrence of various faults such as discoloration, snail trail, burn marks, delamination, and glass breakage. This degradation in power output has created a concern to improve PVM performance. Automatic inspection and condition monitoring of PVM components can handle performance-related issues, especially for installed capacity where no trained personnel are available at the location. This paper describes a deep learning-based technique involving convolutional neural networks (CNNs) to extract features from aerial images obtained from unmanned aerial vehicles (UAVs) and classify various types of fault occurrences using cloud computing and Internet of things (IoT). The algorithm used demonstrates a binary classification with high accuracy by comparing individual faults with good condition. Efficient and effective fault detection can be observed from the results obtained.

Characterisation of visual defects on installed solar photovoltaic (PV) modules in different climatic zones in Ghana

Visual defects on photovoltaic (PV) modules depend on climatic conditions and hence, vary from one country to another. This study characterised visual defects on PV modules installed in three climatic zones in Ghana and determined the link between the defective modules and output power degradation. It identified and classified these defects according to climatic zones and age groups of the modules. It also compared the degradation rates of the modules with visual defects and those without visual defects to determine the influence of the visual defects on output power degradation of the modules. The study used 104 PV modules of different technologies, which were older than 5 years, selected from 16 PV systems installed in the three climatic zones. A walkthrough visual inspection of the modules was performed to observe the visible defects, followed by current-voltage (I-V) curve tracing. The results revealed that encapsulant discoloration and corrosion of frames were found on 50% and 30% of the modules respectively. The other identified visual defects include encapsulant delamination, corrosion of metallisation, sealant infiltration, snail track and cracks in cells, which were few. Encapsulant discoloration was predominant in all the climatic zones and highest in Interior Savannah Climatic Zone while corrosion of frame was prevalent in Dry Equatorial Climatic Zone. The recently installed PV modules succumbed more to these defects than those installed years ago. Overall, modules with visual defects degraded at faster rates than those without visual defects, but the output power degradation could not be wholly attributed to these visual defects because some of the modules with severe visual defects degraded lesser than some of the modules with minor or no visual defects and vice versa. However, the visual defects provided initial clues about the degradation of the modules. Thus, regular visual inspection of the modules should be carried out for early identification of these defects to detect problems that could lead to failures in the future.

Multimodal MEMS vibration energy harvester with cascaded flexible and silicon beams for ultralow frequency response

Scavenged energy from ambient vibrations has become a promising energy supply for autonomous microsystems. However, restricted by device size, most MEMS vibration energy harvesters have much higher resonant frequencies than environmental vibrations, which reduces scavenged power and limits practical applicability. Herein, we propose a MEMS multimodal vibration energy harvester with specifically cascaded flexible PDMS and “zigzag” silicon beams to simultaneously lower the resonant frequency to the ultralow-frequency level and broaden the bandwidth. A two-stage architecture is designed, in which the primary subsystem consists of suspended PDMS beams characterized by a low Young’s modulus, and the secondary system consists of zigzag silicon beams. We also propose a PDMS lift-off process to fabricate the suspended flexible beams and the compatible microfabrication method shows high yield and good repeatability. The fabricated MEMS energy harvester can operate at ultralow resonant frequencies of 3 and 23 Hz, with an NPD index of 1.73 μW/cm3/g2 @ 3 Hz. The factors underlying output power degradation in the low-frequency range and potential enhancement strategies are discussed. This work offers new insights into achieving MEMS-scale energy harvesting with ultralow frequency response.

Automatic PV Array Reconfiguration under Partial Shading Conditions

Photovoltaic (PV) arrays have been recognized as one of the main clean renewable sources of electrical energy. In practice, PV arrays are subject to unavoidable non-uniform partial shading (PS) due to clouds, buildings, dust, etc. PS causes the hot spot problem, mismatch losses, and output power degradation. A widely used approach to mitigate the effect of PS is dynamic reconfiguration, where, the interconnection of PV panels is modified according to the shading condition to achieve maximum output. Dynamic reconfiguration techniques use sensors, a programmable controller, and a switch matrix for optimal operation. However, they have drawbacks such as system complexity and scalability issues. For instance, reducing the number of switches limits the flexibility of the reconfiguration algorithm. In this paper, an automatic dynamic reconfiguration scheme is proposed in which PV panel irradiation activity controls the interconnection of switches, without the need for a programmable controller. A modular building block is proposed from which easily scalable PV arrays can be constructed in a hierarchical manner. Experimental and analytic results have verified the effectiveness of the proposed reconfiguration scheme.

Process challenges of high-performance silicon heterojunction solar cells with copper electrodes

Substitution of expensive silver paste becomes essential for mass production of silicon heterojunction (SHJ) solar cell, which calls for high efficiency and low-cost metallization techniques. Copper metallization together with multi-busbar cell interconnection is considered as effective way to low shading loss and electrode ohmic loss. While, the electrode adhesion and parasitic plating are the key process challenges limiting the copper metallization of SHJ solar cells. In this research, the copper plated SHJ solar cells with high electrode aspect ratio and an efficiency of 23.35% have been achieved on M2 wafers. The SEM images show the holes in the plated layers will deteriorate the adhesion between plated copper and seed-layer. The glass/back sheet structure (GBS) modules have been laminated to evaluate the influence of parasitic plating on damp-heat (DH) performance. The degradation in output power ( P max ) is up to 4.90%, which is primarily due to a decreased open-circuit voltage ( V oc ) and fill factor ( FF ). It can be ascribed to the deteriorated surface recombination and interconnection. Although the parasitic plating on the wafer edge has ignorable influence on damp heat test after etch-back process, it is still necessary to protect the cell edge to avoid parasitic plating. The research evaluates the process challenges of copper metallization of SHJ solar cells, which offers a refer for achieving high reliability and low levelized cost of energy (LCOE) of photovoltaic power generation. • This work evaluates the challenge of ghost plating on high-performance SHJ solar cells and modules for the first time. • The surface morphology and element distribution at the interface is analyzed and an efficiency of 23.35% is obtained. • The glass/back sheet modules have been laminated to evaluate the influence of ghost plating on damp-heat (DH) performance.

Improvement in the reliability of crystalline silicon solar cell interconnection by using Nickel Micro-Plating Bonding (NMPB) technology

It is popular to research promoting the light conversion efficiency of crystalline silicon solar cell photovoltaic (PV) modules. However, excellent light conversion efficiency does not mean it could maintain initial performance after long-term running. Long-term reliability of interconnection to assemble crystalline silicon solar cells in PV modules is critical to ensure that the device performs continually for up to 20 years. It is reported that most crystalline PV modules fail from corrosion and breakage of the interconnector with the solder joint. As a result, improvement of interconnection technology is highly necessary. Nickel (Ni) Micro-Plating Bonding (NMPB) is an innovative interconnection technology for crystalline silicon solar cells: copper ribbons bonded with lead or lead-free solder are replaced by copper wires bonded with Ni electroplating film. The NMPB interconnection provides key advantages: low temperature (55 °C) process, enhancement of reliability from strain and stress caused by high temperature, and coefficient of thermal expansion (CTE) mismatch between metal and silicon. Furthermore, the material of NMPB, Ni, possesses excellent corrosion resistance. High reliability was confirmed with about 1.9% degradation of output power for up to 1000 thermal cycling tests and 3.8% for 1000 h of damp heat tests in bare NMPB solar cells, while 64.7% degradation in thermal cycling tests and 23.0% in damp heat tests were confirmed in solder bonding solder cells.

Reliability Analysis of AlGaN-Based Deep UV-LEDs

The current pandemic crisis caused by SARS-CoV-2 has also pushed researchers to work on LEDs, especially in the range of 220-240 nm, for the purpose of disinfecting the environment, but the efficiency of such deep UV-LEDs is highly demanding for mass adoption. Over the last two decades, several research groups have worked out that the optical power of GaN-based LEDs significantly decreases during operation, and with the passage of time, many mechanisms responsible for the degradation of such devices start playing their roles. Only a few attempts, to explore the reliability of these LEDs, have been presented so far which provide very little information on the output power degradation of these LEDs with the passage of time. Therefore, the aim of this review is to summarize the degradation factors of AlGaN-based near UV-LEDs emitting in the range of 200-350 nm by means of combined optical and electrical characterization so that work groups may have an idea of the issues raised to date and to achieve a wavelength range needed for disinfecting the environment from SARS-CoV-2. The performance of devices submitted to different stress conditions has been reviewed for the reliability of AlGaN-based UV-LEDs based on the work of different research groups so far, according to our knowledge. In particular, we review: (1) fabrication strategies to improve the efficiency of UV-LEDs; (2) the intensity of variation under constant current stress for different durations; (3) creation of the defects that cause the degradation of LED performance; (4) effect of degradation on C-V characteristics of such LEDs; (5) I-V behavior variation under stress; (6) different structural schemes to enhance the reliability of LEDs; (7) reliability of LEDs ranging from 220-240 nm; and (8) degradation measurement strategies. Finally, concluding remarks for future research to enhance the reliability of near UV-LEDs is presented. This draft presents a comprehensive review for industry and academic research on the physical properties of an AlGaN near UV-LEDs that are affected by aging to help LED manufacturers and end users to construct and utilize such LEDs effectively and provide the community a better life standard.

Efficiency Droop and Degradation in AlGaN-Based UVB Light-Emitting Diodes

In this study, we found that the current droop (J-droop) in AlGaN-based UVB light-emitting diodes was more obvious at higher temperatures, despite both the main and parasitic peaks undergoing monotonic decreases in their intensity upon an increase in the temperature. The slower temperature droop (T-droop) did not occur when the forward current was increased to temperatures greater than 298 K. After an aging time of 6000 h, the emission wavelengths did not undergo any obvious changes, while the intensity of the parasitic peak barely changed. Thus, the degradation in the light output power during long-term operation was not obviously correlated to the existence of the parasitic peak.

Internal Characterization-Based Prognostics for Micro-Direct-Methanol Fuel Cells under Dynamic Operating Conditions.

Micro-direct-methanol fuel cells (DMFCs) use micro-electro mechanical system (MEMS) technology, which offers high energy density, portable use, quick replenishment, and free fuel reforming and purification. However, the DMFC is limited by a short effective service life due to the membrane electrode’s deterioration in electrochemical reactions. This paper presents a health status assessment and remaining useful life (RUL) prediction approach for DMFC under dynamic operating conditions. Rather than making external observations, an internal characterization is used to describe the degradation indicator and to overcome intrusive influences in operation. Then, a Markov-process-based usage behavior prediction mechanism is proposed to account for the randomness of real-world operation. The experimental results show that the proposed degradation indicator alleviates the reduction in DMFC output power degradation behavior caused by the user loading profile. Compared with the predictions of RUL using traditional external observation, the proposed approach achieved superior prognostic performance in both accuracy and precision.

Comparisons between high power fiber systems in the presence of radiation induced photodarkening

Performance of high power fiber lasers and amplifiers with different pump sources are evaluated in the presence of radiation induced photodarkening in post-irradiated active fibers. Evolutions of output power and thermal mode instability threshold under different radiation doses are examined and analyzed. Severe degradation in both output power and thermal mode instability threshold is recorded for high power fiber systems with their active fibers exposed to radiations. Comparisons show that, amplifiers present a relatively better performance than lasers in adverse environments. Besides, 976 nm pump source is more favorable for high power laser sources in radioactive applications, even though 915 nm pump ensures a much lower temperature profile inside the active fiber.

Particular aspects of determining reliability indicators of thermoelectric generator modules using experimental data

Resource tests allowed finding that the relative degradation of output power and efficiency of thermoelectric generator modules is not subject to linear law. This means that the distribution law for the failure time of such modules does not «copy» the distribution of their initial parameters, i.e. is neither normal nor logarithmically normal. Therefore, the aim of this paper is to find or select from among the existing such a failure time distribution law, which would clearly take into account the scattering of the rates of relative degradation of the parameters of thermoelectric generator modules. The paper substantiates the need to use diffusion-nonmonotonic failure time distribution for processing the results of resource tests of thermoelectric generator modules in order to determine their standardized reliability indicators and relative errors of the obtained values. It is proposed to determine the point estimates of the parameters of the law, namely the average failure time and the parameter of variation of the rate of degradation processes not by formulas obtained by the method of maximum likelihood, but by smoothing the probability of failure-free operation obtained by tests. The least squares method and Newton's method are used. Estimates obtained by the method of maximum likelihood serve as an initial approximation for Newton's method. This allows achieving significantly less error in determining standardized reliability indicators than when using the method of maximum likelihood.

Light-induced performance of SHJ solar modules under 2000 h illumination

The light-induced degradation (LID) of solar module leads to severe loss in generated power due to the formation of recombination active defects. The silicon heterojunction (SHJ) solar cells based on n-type wafers are less affected by the LID test. In this paper, the glass/back sheet structure (GBS) modules with different encapsulant materials (TPO, POE, EVA) were laminated to evaluate their performance changes under 2000 h light soaking stress for the first time. The current-voltage (light I–V, dark I–V) parameters of the modules were measured, as well as the external quantum efficiency (EQE) and electroluminescence (EL), to verify the effect of light irradiation on SHJ solar modules. The SHJ modules with different encapsulant materials show excellent light-induced reliability. There is no degradation after 2000 h light irradiation, and even exhibits light-induced performance increase. The gain in output power (Pmax) is up to 1.41%, which is primarily due to an improved open-circuit Voltage (Voc) and fill factor (FF) as the result of a reduced density of recombination-active interface states. The front sheet/back sheet (FBS) modules also verified the accumulated light-induced stress could result in deteriorating interconnection between SHJ solar cell and ribbon, which suffers from significant output power degradation. The LID-free SHJ solar cells show great potential for lower levelized cost of energy (LCOE) of photovoltaic power generation.

Degradation analysis of installed solar photovoltaic (PV) modules under outdoor conditions in Ghana

Photovoltaic (PV) module degradation rate depends on technology, manufacturer and environmental conditions. This makes it challenging to transfer the results of degradation analysis from one country to another. Thus, the increase in deployment of PV systems in Ghana makes degradation analysis a necessity. This study quantified the degradation rates and predicted the lifetime of 16 PV systems of different module technologies and age groups installed in different locations under outdoor conditions in Ghana to provide a better understanding of the long-term behavior of installed PV systems in Ghana. It presented the frequency distribution of output power degradation of different PV module technologies, estimated their power degradation rates, and predicted and compared the lifetime of these technologies. The country was grouped into three strata and 104 PV modules of different technologies which were older than 5 years were selected from 16 PV systems in these strata, depending on availability and accessibility. The electrical parameters of the PV modules were measured by current–voltage (IV) tracing. The results revealed that crystalline silicon modules degraded less than amorphous silicon. The median and mean power degradation rates of, monocrystalline silicon were 1.23%/year and 1.37%/year respectively, polycrystalline silicon were 1.35%/year and 1.44%/year respectively and, amorphous silicon were 1.65%/year and 1.67%/year respectively. Overall, the median and mean predicted lifetime of the PV systems (crystalline and amorphous silicon) were 14 year and 16 years respectively but the median lifetime of both monocrystalline and polycrystalline modules was 16 years while that of amorphous was 13 years. It was predicted that 50% of PV modules studied would fail before 15 years, indicating that most of the PV modules in Ghana are unlikely to operate for the 25 years warranty, signifying less power output and shorter lifetime of the modules which could discourage the widespread implementation of PV systems in Ghana.

Material study of photovoltaic modules with silicone encapsulation after long-term outdoor exposure

In this study we analyze the properties of silicone elastomers used in the fabrication of PV modules in the early 1980's, which were in operation outdoors in a semi-tropical climate for more than 20 years. We observe that the silicone materials have very similar properties to recent, freshly cured silicone. The information gathered gives evidence that silicone elastomers undergo only very limited degradation after years of exposure in the field in operating PV modules. A moderate decrease in elastic modulus was observed, but further studies are needed to determine whether this effect is real. The very limited degradation of silicone encapsulant is consistent with the low performance decrease reported in other studies. - Insights into nineteen eighties module designs - Material analysis of solar cell encapsulant after 20 years of outdoor exposure - Properties of the silicone materials under study are very similar to those of recent, freshly cured material - Correlation between limited encapsulant material degradation and limited power output degradation - Direct comparison between fresh silicone encapsulant and same material after 20 years of exposure in modules in operation

Photonic Crystal Surface Emitting Laser Operating in Pulse-Periodic Regime with Ultralow Divergence Angle

The nanosecond-level pulse-operation characteristics of photonic-crystal surface-emitting lasers (PCSELs) with ultralow divergence were investigated in detail. We demonstrate a maximum peak output power of 14 W for a current pulse width of 9 ns, which is about 28 times the saturated power under continuous wave (CW) operation. The full width at half maximum (FWHM) of the optical response pulse is about 3 ns wider than the current pulse. The maximum repetition frequency reaches 400 kHz at 10 A without significant degradation of output power while the value is 100 kHz at 40 A. Moreover, the multimode behavior of the PCSEL at a high peak current was analyzed.

Dynamic Supply Voltage Control for PA Output Power Correction Under Variable Loading Scenarios

This article presents an automatic system that is able to dynamically restore the output power capability of a power amplifier (PA) under variable loading scenarios. This is accomplished by dynamically adapting the supply voltage, VDD, of the PA according to the developed theoretical model. To dynamically vary VDD, a GaN dc-dc converter, based on the commercial EPC 9067 Demo Board, was used. The load is measured using an impedance meter, which is based on the slotted line principle and was specifically designed for low insertion loss. This impedance meter also generates a load-dependent pulsewidth modulated signal that controls the dc-dc converter switching, regulating VDD. The prototype was designed for 3.55 GHz and tested with CW and modulated signal excitations, being able to compensate the output power degradation under variable loading conditions inside a 2.1 voltage standing wave ratio circle. For a constant gain compression level, the average efficiency degradation over the tested range of impedances is less than 5%, and the average power improvement is 0.7 dB. The worst case measured output power of the PA is compensated from 37.0 to 39.9 dBm, which corresponds to a 2.9 dB improvement. Using a modulated signal excitation, the peak envelope power, which is compressed by almost 3 dB without VDD compensation, is restored, and the average output power is improved by 0.6 dB. The system can track the load and adjust VDD with a worst case step-up delay of 25 ms.

Micro Gas Turbine Range Extender Performance Analysis Using Varying Intake Temperature

A micro gas turbine (MGT) can potentially be an alternative power source to the conventional internal combustion engine as a range extender in hybrid electric vehicles. The integration of the MGT into a hybrid vehicle needs a new approach for technical validation requirements compared to the testing of an internal combustion engine. Several attributes of the MGT are predicted to cause concerns for vehicle sub-system requirements such as high ambient temperature and start-stop behaviour. This paper describes the results from specially developed experimental techniques for testing the MGT in a typical automotive environment. A black box MGT was used in this study for performance investigation during hot and cold starts. The MGT was instrumented and fitted with automotive standard components to replicate typical vehicle operational conditions. The intake air temperature was varied between 10 and 24 °C. A significant reduction in the power output of the MGT was observed as the intake temperature was increased. The proposed case scenario caused a reduction in nitrogen oxide emissions in the range of 0.02−0.04 g/km because of the lower combustion temperature at high intake temperature. However, hydrocarbon and carbon monoxide emissions have not shown a noticeable reduction during the power output degradation. The experimental results have highlighted the potential issues of using the MGT at higher intake temperatures and suggest design change to take the effect of higher engine bay temperature into account.