114 research outputs found
Nanosphere concentrated photovoltaics with shape control
No full textDielectric colloidal nanospheres (NSs) are promising candidates for light management in photonic devices such as solar cells (SCs). NS arrays can direct the broad incident solar radiation into a set of tighter foci, at which light intensity becomes considerably concentrated, enabling higher photovoltaic conversion efficiency. Furthermore, the NS arrays acting as an effective medium on the SC surface can reduce reflectance and facilitate improved forward scattering. Therefore, uniform arrays of NSs located on top of the SC can behave as antireflection coatings or as microlenses, which can be regarded as a surface distributed light concentrator within the framework of concentrated photovoltaics. Fabrication of NS‐based light‐trapping structures is low‐cost and less complicated than common alternatives such as vacuum evaporated multilayer antireflection coatings. In this work, experimental demonstration and computational confirmation on the shape adjustment of such NS structures for improved light harvesting and efficiency enhancement in Si SCs are studied. The light conversion efficiency of Si solar cells is shown to improve by more than 27% with shape adjustment of NS arrays
Automated estimation of link quality for Lora: A remote sensing approach
No full textMany research and industrial communities are betting on LoRa to provide reliable, long-range communication for the Internet of Things. This new radio technology, however, provides widely heterogeneous coverage; a LoRa link may span hundreds of meters or tens of kilometers, depending on the surrounding environment. This high variability is not captured by popular channel models for LoRa, and on-site measurementsÐa common alternativeÐare impractical due to the large geographical areas involved. We propose a novel, automated approach to estimate the coverage of LoRa gateways prior to deployment and without on-site measurements. We achieve this goal by combining free, readily-available multispectral images from remote sensing with the right channel model. Our processing toolchain automatically classifies the type of environment (e.g., buildings, trees, or open fields) traversed by a link, with high accuracy (>90%) and spatial resolution (10×10m2). We use this information to explain the attenuation observed in experiments. As signal attenuation is not well captured by popular channel models, we focus on the Okumura-Hata empirical model, hitherto largely unexplored for LoRa, and show that i) it yields estimates very close to our observations, and ii) we can use our toolchain to automatically select and configure its parameters. A validation on 8,000+ samples from a real dataset shows that our automated approach predicts the expected signal power within a ∼10dBm error, against the 20ś40dBm of popular channel models.Embedded System
6.Rasit Turan, Mustafa Kulakci, Selcuk Yerci, Ilker Dogan, Arife Gencer Imer, Ilker Yildiz and Ayse Seyhan, “Si, Ge and SiGe Nanocrystals Embedded in Transparent Matrices for Light Conversion for Solar Cell Applications
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Fabrication and chracterization of Si nanocrystals in SiC multilayer film for third generation photovoltaics
No full textThe effect of the post annealing on the formation of nanocrystalline SiC film deposited by PECVD at low temperature
No full textEffect of particle properties and light polarization on the plasmonic resonances in metallic nanoparticles
No full textThe resonance behavior of localized surface plasmons in silver and gold nanoparticles was studied in the visible and near-infrared regions of the electromagnetic spectrum. Arrays of nano-sized gold (Au) and silver (Ag) particles with different properties were produced with electron-beam lithography technique over glass substrates. The effect of the particle size, shape variations, period, thickness, metal type, substrate type and sulfidation were studied via transmission and reflectance measurements. The results are compared with the theoretical calculations based on the DDA simulations performed by software developed in this study. We propose a new intensity modulation technique based on localized surface plasmons in nanoparticles with asymmetric shapes. (C) 2010 Optical Society of Americ
Effect of Ambient Conditions on Monthly Performances of Three Different PV Arrays
No full text11th ISES EuroSun Conference -- OCT 11-14, 2016 -- Palma, SPAINSolar PV cells may be mainly divided into two parts as crystalline and thin film. Mono-crystalline silicon (e.g. Mono-Si) and microcrystalline based amorphous silicon and other thin films (e.g. gc-Si/a-Si and CdTe thin films) are widely used PV cells in the arrays. The outdoor performances of these systems depend on some climatic parameters and conditions, and it is important to understand how the monthly efficiencies vary with these parameters. In the present study, the data obtained from three grid connected PV arrays of Mono Si, a-Si/p.c-Si and CdTe thin film that were operated for 41 months in Ankara-Turkey is analyzed. The results showed that Mono-Si an-ay performance depends on the 5 parameters of outdoor climatic conditions while a-Si/gc-Si and CdTe thin film arrays performances arc not significantly affected by the variation of the climatic parameters. The possible reasons are discussed in details.Univ Illes Balears, UIB Congres, Asoc Espanola Energia Solar, Int Solar Energy Soc, Int Solar Energy SocTUBITAK from 2218 programThe authors would like to thank B. Aksoy and MGM for the supply of meteorological data. The helps of Mr. C. Guenc Ogulgoen, Mr. Harun Tanik and Mr. Ugur Yardim during installation, maintenance and data handling are acknowledged. One of the authors thanks to TUBITAK for the support from 2218 program.WOS:00042689510012
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