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Photovoltaic panel cooling by atmospheric water sorptiona??evaporation cycle
摘要： More than 600 GW of photovoltaic panels are currently installed worldwide, with the predicted total capacity increasing very rapidly every year. One essential issue in photovoltaic conversion is the massive heat generation of photovoltaic panels under sunlight, which represents 75–96% of the total absorbed solar energy and thus greatly increases the temperature and decreases the energy efficiency and lifetime of photovoltaic panels. In this report we demonstrate a new and versatile photovoltaic panel cooling strategy that employs a sorption-based atmospheric water harvester as an effective cooling component. The atmospheric water harvester photovoltaic cooling system provides an average cooling power of 295 W m–2 and lowers the temperature of a photovoltaic panel by at least 10 °C under 1.0 kW m–2 solar irradiation in laboratory conditions. It delivered a 13–19% increase in electricity generation in a commercial photovoltaic panel in outdoor field tests conducted in the winter and summer in Saudi Arabia. The atmospheric water harvester based photovoltaic panel cooling strategy has little geographical constraint in terms of its application and has the potential to improve the electricity production of existing and future photovoltaic plants, which can be directly translated into less CO2 emission or less land occupation by photovoltaic panels. As solar power is taking centre stage in the global fight against climate change, atmospheric water harvester based cooling represents an important step toward sustainability.
关键词： atmospheric water harvester,cooling strategy,energy efficiency,sustainability,photovoltaic panels
更新于2025-09-23 15:21:01
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Energy-Efficient QoS-based OCDMA Networks Aided by Nonlinear Programming Methods
摘要： One of the advantages of the optical code division multiple access (OCDMA) system networks over other multiple access methods is the ability to provide differentiated classes of quality of service (QoS) for different users. The performance of the OCDMA networks is mainly limited by the multi-access interference (MAI) coming from other users sharing the same spectral resources. The suitable resource allocation in OCDMA networks allows greater capacity and the reliable deployment of the available resources in the network. This work aiming at applying and analyzing four analytical optimization methods applied to energy efficiency (EE) maximization of OCDMA networks. Hence, such optimization methods were applied and their performance-complexity tradeoffs are compared, namely the augmented Lagrangian method (ALM) [18], sequential quadratic programming method (SQP), majoration-minimization (MaMi) approach [23], [24], as well as Dinkelbach’s method (DK). Tests were performed considering practical and realistic OCDMA networks with a wide range of nodes, typically K = {8; 16; 32} nodes. The evaluated optimization methods were able to achieve convergence and perform suitably to solve the optical EE-OCDMA optimization problem. However, in a few specific high loading system configurations, the DK method did not reach full convergence; besides DK processing time was much greater compared to the promising ALM, SQP and MaMi EE-OCDMA optimization approaches.
关键词： CvX,OCDMA networks,Energy efficiency,Majoration-minimization,Sequential quadratic Programming method,Augmented Lagrangian method,Dinkelbach’s fractional optimization method
更新于2025-09-23 15:21:01
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Efficiency analysis of photovoltaic systems
摘要： The goal of the study was to analyse the efficiency of two existing photovoltaic micro-installations with the power of approx. 40 kWp. The main factor differing the two installations being analysed was the arrangement of modules in relation to the sides of the world, one is south-west and the other is east-west. The total yield of electrical energy in 2017 from the south-west installation was higher and amounted to 34980 kWh. For the east-west installation the amount of energy generated was equal to 31180 kWh. 4 methods of forecasting electrical energy yield were discussed. Simple computational method proved to be the best method for both installations.
关键词： photovoltaic systems,renewable energy,efficiency
更新于2025-09-23 15:21:01
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Dynamic global maximum power point tracking of the PV systems under variant partial shading using hybrid GWO-FLC
摘要： Maximum power point tracker (MPPT) techniques have been used to extract the maximum power available form photovoltaic (PV) energy systems. Conventional MPPT techniques like perturb and observe (P&O), hill climbing (HC), incremental conductance etc. were good enough to track the maximum power for the unshaded PV systems because it has only one power peak in the P-V curve. In the case of partial shading conditions (PSC), many peaks are created; one global maximum power point (GMPP) and many local maximum power points (LMPPs). Most of conventional MPPT techniques may stick to one of the LMPPs, which reduce the MPPT efficiency of PV systems. Soft computing techniques like particle swarm optimization (PSO), gray wolf optimization (GWO), and Cuckoo search optimization (CSO) etc. can catch the GMPP of PV system under the same PSC. These latter techniques suffer from two problems, the first problem is the high oscillations around the GMPP, the second problem is that, they cannot follow the new GMPP once it changed its position due to the searching agents will be busy around old GMPP caught. The solution of these two problems are the motivation of this research. GWO has been used to catch the GMPP and the problem of oscillations around the GMPP has been solved by hybridizing this technique with fuzzy logic controller (FLC) for soft tune the output generated power at the GMPP. The FLC characterizes by accurate GMPP catching with almost zero oscillations. The second problem is solved in this paper by re-initializing the GWO with two new initialization techniques. The results obtained from GWO-FLC with two different re-initialization techniques have been compared to the results of PSO without reinitializing its particles. The results obtained from this work prove the superior performance of the new proposed technique in terms of dynamic GMPP catching and MPPT power efficiency in case of time variant PSCs.
关键词： Global maximum power point,Fuzzy logic controller,MPPT energy efficiency,Partial shading condition,Particle swarm optimization,Grey wolf optimization
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE Sustainable Power and Energy Conference (iSPEC) - Beijing, China (2019.11.21-2019.11.23)] 2019 IEEE Sustainable Power and Energy Conference (iSPEC) - Detection of High-Impedance Line-Line Fault in Photovoltaic Arrays Based on Voltage Divider
摘要： The recently proposed dual mode logic (DML) gates family enables a very high level of energy-delay optimization flexibility at the gate level. In this paper, this flexibility is utilized to improve energy efficiency and performance of combinatorial circuits by manipulating their critical and noncritical paths. An approach that locates the design’s critical paths and operates these paths in the boosted performance mode is proposed. The noncritical paths are operated in the low energy DML mode, which does not affect the performance of the design, but allows significant energy consumption reduction. The proposed approach is analyzed on a 128 bit carry skip adder. Simulations, carried out in a standard 40 nm digital CMOS process with VDD = 400 mV, show that the proposed approach allows performance improvement of X2 along with reduction of energy consumption of X2.5, as compared with a standard CMOS implementation. At VDD = 1.1 V, improvements of 1.3X and 1.5X in performance and energy are achieved, respectively.
关键词： energy efficiency,Dual Mode Logic,critical paths,energy-delay optimization,high performance
更新于2025-09-23 15:19:57
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Analysis of novel passive cooling strategies for free-standing silicon photovoltaic panels
摘要： Silicon-based photovoltaic (PV) panels are sensitive to operating temperatures, especially during exposure to high solar irradiation levels. The sensitivity of PV panels is reflected through the reductions in photovoltaic energy conversion efficiency (electrical efficiency) and in PV panel lifetime due to thermal fatigue. In this study, different and novel passive cooling strategies were proposed and numerically investigated for the case of 50-W market-available free-standing silicon PV panels. The focus of the research was to examine the effect of the proposed modifications on the temperatures of the specific PV panel layers as well as on the velocity contours. The used numerical model was upgraded based on a previously developed numerical model that was validated through an experimental manner. Three different passive cooling scenarios were numerically investigated, and the most promising one was the case where the PV panel was provided with slits through the front PV panel surface resulting in a reduction of about 4 °C for the PV panel operating temperature. The other examined cases proved to be less effective with the detected temperature reduction being less than 1.0 °C. The consideration of novel PV panel frame materials was found to be a viable possibility. It was also found that all the proposed modifications can generally lead to the performance improvement in the PV panels and reduce the materials spent on the production of commercial PV panels.
关键词： Photovoltaics,Numerical analysis,Passive cooling,Renewable energy,Energy efficiency
更新于2025-09-23 15:19:57
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[IEEE 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM) - K?¤rdla, Estonia (2019.6.12-2019.6.15)] 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM) - Impact of LED Thermal Stability to Household Lighting Harmonic Load Current Modeling
摘要： This paper focuses on energy efficiency aspects and related benefits of radio-access-network-as-a-service (RANaaS) implementation (using commodity hardware) as architectural evolution of LTE-advanced networks toward 5G infrastructure. RANaaS is a novel concept introduced recently, which enables the partial centralization of RAN functionalities depending on the actual needs as well as on network characteristics. In the view of future definition of 5G systems, this cloud-based design is an important solution in terms of efficient usage of network resources. The aim of this paper is to give a vision of the advantages of the RANaaS, to present its benefits in terms of energy efficiency and to propose a consistent system-level power model as a reference for assessing innovative functionalities toward 5G systems. The incremental benefits through the years are also discussed in perspective, by considering technological evolution of IT platforms and the increasing matching between their capabilities and the need for progressive virtualization of RAN functionalities. The description is complemented by an exemplary evaluation in terms of energy efficiency, analyzing the achievable gains associated with the RANaaS paradigm.
关键词： power model,radio access networks,RAN-as-a-service,LTE-advanced,5G,wireless communication,cloud-RAN,Energy efficiency
更新于2025-09-23 15:19:57
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[IEEE 2019 International Conference on Electrical, Communication, and Computer Engineering (ICECCE) - Swat, Pakistan (2019.7.24-2019.7.25)] 2019 International Conference on Electrical, Communication, and Computer Engineering (ICECCE) - Modeling and Analysis of Novel Tandem Solar Cells
摘要： While relay-based cooperative networks (widely known in the literature as cooperative communication), where relays only forward signals from the sources to the destination, have been extensively researched, fully cooperative systems have not been thoroughly examined. Unlike relay networks, in a fully cooperative network, each node acts as both a source node sending its own data and a relay forwarding its partner’s data to the destination. Mutual cooperation between neighboring nodes is believed to improve the overall system error performance, especially when space-time codes are incorporated. However, a comprehensive performance analysis of space-time-coded fully cooperative communication from all three perspectives, namely error performance, outage probability, and energy efficiency, is still missing. Answers to the commonly asked questions of whether, in what conditions, and to what extent the space-time-coded fully cooperative communication is better than direct transmission are still unknown. Motivated by this fact and inspired by the increasing popularity of healthcare applications in wireless body area networks (WBANs), this paper derives for the first time a comprehensive performance analysis of a decode-and-forward space-time coded fully cooperative communication network in Rayleigh and Rician fading channels in either identically or non-identically distributed fading scenario. Numerical analysis of error performance, outage probability, and energy efficiency, validated by simulations, show that fully cooperative communication is better than direct transmission from all three aspects in many cases, especially at a low-power and low signal-to-noise ratio regime, which is a typical working condition in WBANs.
关键词： symbol error rates,energy efficiency,MIMO,space-time codes,Rician,decode-and-forward,outage probability,wireless body area networks,Cooperative communication,Rayleigh
更新于2025-09-23 15:19:57
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Illuminating homes with LEDs in India: Rapid market creation towards low-carbon technology transition in a developing country
摘要： Near-term climate change mitigation calls for technological innovation and widespread implementation of appropriate technologies. This is salient in emerging economies, where impending socio-economic and infrastructural transitions hold immense potential for locking-in low-carbon development pathways. Yet, little is understood about how developing countries can scale appropriate technology transitions, given their often underdeveloped technological innovation capabilities and supporting infrastructures and finances. This paper examines a recent, rapid, and ongoing transition of India's lighting market to light emitting diode (LED) technology, from a negligible market share to LEDs becoming the dominant lighting products within five years, despite the country's otherwise limited visibility in the global solid-state lighting industry. Annual sales of LED bulbs grew more than 130 times to over 650 million bulbs between 2014–2018, with over 30 billion kWh of estimated annual energy savings. Focusing on this striking story of technology transition, this paper analyzes India's LED uptake using semi-structured interviews and drawing on the technology innovation systems literature. The results show that the success of transition coexists with its share of shortfalls, and that there is an important tension between the lowering of upfront costs of low-carbon technologies and the efforts to enhance domestic technological capabilities. The paper discusses the results for the Indian LED case and emphasizes the importance of consistent strategic action taking into account all (and not limited) parts of the technology innovation system, while also providing insights on how mitigation technologies can be developed and deployed in developing countries.
关键词： Technology innovation systems,Light emitting diode (LED),Developing countries,India,Solid state lighting,Climate change mitigation,Energy efficiency
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Miramar Beach, FL, USA (2019.8.19-2019.8.21)] 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - 2D Material Printer: A Novel Deterministic Transfer Method for On-Chip Photonic Integration
摘要： As green communication becomes an inevitable trend for future 5G wireless networks, how to maximize the energy efficiency (EE) of device-to-device (D2D) communication has drawn extensive attention recently. However, most of existing works only optimize the EE in the single-cell scenario, while little attention is paid to maximizing the EE of the whole cellular network underlaid with D2D communication with randomly distributed users on multiple bands. In this paper, we first consider the whole cellular network underlaid with D2D communication on multiple bands and derive the exact expressions of the successful transmission probabilities, the average sum rate and the EE based on stochastic geometry theory. Then, we formulate the optimization problem of maximizing the EE subject to four constraints regarding to transmission power and outage probabilities, and the non-convexity of this problem is also verified. After that, by exploiting the objective function property of being the sum of several functions, we propose a derivative-based algorithm to solve this non-convex optimization problem. Our theoretical analysis shows that the computational complexity of the proposed algorithm is significantly lower than that of the conventional branch and bound algorithm. Finally, simulation results demonstrate that the proposed algorithm can achieve the near-optimal EE with much better performance than the conventional algorithm.
关键词： energy efficiency,5G,D2D communication,stochastic geometry
更新于2025-09-23 15:19:57