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This report demonstrates the synthesis and properties of large-area well aligned air-stable ZnO/ZnSe core/shell nanowires on a large area transparent conducting substrate (TCO) by combining chemical vapor deposition (CVD) and pulsed laser deposition (PLD) techniques. the ZnO nanowire were uniformly and perpendicularly grown on the TCO substrate and the ZnSe shell with a thickness of 5–8 nm were epitaxially...
In the present status of the PV market, new approaches for introducing novelties and more efficient concepts are continuously under consideration. Concentration of light over the solar cell is certainly a very old topic but not old fashioned. The fast industrialization of current CPV modules are evidencing important fields of development not fully solved which call for immediate solutions.
It is known that nearby lightning strikes can induce overvoltages in photovoltaic arrays. However, although many laboratory studies have been reported, relatively few field studies have appeared in the literature. This paper reports on a field study conducted at South Dakota State University and the Florida Solar Energy Center in which a high-speed datalogger was used to monitor the voltage at the...
A new two mirror concentrating photovoltaic module making use of Kohler integration optics is introduced. A brief design background is included. First test results from a 15 Watt prototype are given.
The III-nitride material system offers substantial potential to develop high-efficiency solar cells. Theoretical modeling of InGaN solar cells indicate strong band bending at the top surface of p-InGaN junction caused due to piezoelectric polarization-induced charge at the strained p-GaN window interface. A counterintuitive strained n-GaN window layer is proposed, modeled and experimentally verified...
We use the combination of high-resolution electron microscopy and density-functional theory to study the atomic structure and electronic effects of grain boundaries in polycrystalline photovoltaic materials such as Si, CdTe, CuInSe2, and CuGaSe2. We find that grain boundaries containing dislocation cores create deep levels in Si, CdTe, and CuGaSe2. Surprisingly, however, they do not create deep levels...
In this paper, monitoring system had been constructed to evaluate and analyze performance of grid-connected PV systems and monitored data have been collected. The approximated output models is designed and verified with monitored data. The performance and losses of PV systems are presented in a quantitative value for changing meteorological conditions. Reliability and validity of an evaluation and...
The surface composition of chemically passivated silicon substrates is investigated using XPS and FTIR techniques. The samples are passivated with methanol, quinhydrone-methanol and iodine-methanol solution after HF treatment. The minority carrier lifetimes of these chemically passivated silicon substrates are also measured. Quinhydrone-methanol solution provides a chemically inert surface and a considerably...
Nanocrystalline silicon (nc-Si:H) is an important material for solar cell applications. Thin films of nc-Si:H can be deposited cost-effectively using chemical vapor deposition (CVD) and sputter deposition. While CVD method offer higher deposition rate and is commonly used in PV industry, microstructural properties (such as hydrogen incorporation, crystallinity, surface morphology, dopant incorporation)...
In this article a new software package for modelling of concentrator solar cell systems is presented. It has been used for modelling different anti-reflection coatings under different irradiation conditions, irradiated directly with the AM1.5 spectrum and considering the optical concentrator system.
GaAs on Si (GaAs/Si) solar cells with AM0 efficiencies in excess of 17% have been demonstrated using Si substrates coated with a step-graded buffer of SixGe1-x alloys graded to 100% Ge. A year of LEO testing of this technology aboard Materials International Space Station Experiment number 5 (MISSE5) was recently competed. Electrical performance data, sun angle and thermal conditions measured on-orbit,...
Hybrid bulk heterojunctions provide a technically and economically credible alternative to conventional silicon based photovoltaic technologies. New hybrid bulk heterojunction solar cells fabricated with a TiO2 aerogel and a series of porphyrins have been studied in this work. The porphyrins act as the sunlight absorber, electron donor, and hole-transporter, while the TiO2 aerogel is the electron...
We used a new method to make carbon catalyst counter electrodes for dye-sensitized solar cells (DSSCs) by coating a fluorine-doped tin oxide (FTO)-glass with carbon nanoparticles from an aqueous colloidal suspension of the blend of carbon nanoparticles (particle size ≪50 nm and surface area ≫ 100 m2/g ) and TiO2. Z-907 dye was used as the sensitizer. The electrolyte effects on device performance were...
Low-cost rear surface passivation has been a critical requirement for fabrication of cost effective high efficiency cells with local back surface field (LBSF) structures. This becomes even more important as we move towards next generation thin solar cells. Various dielectrics have been attempted in combination with boron and aluminum BSF to fabricate high efficiency LBSF cells. However there is no...
To determine solar cell spectral response (SR) at working illumination conditions, measurements of the signal generated by a modulated spectral beam imposed on a DC short circuit current due to white light bias with different irradiances are typically used. In practice the bias light source does not usually simulate the sun's spectrum. However the effect of the spectral composition of the bias light...
An upconversion-based solar cell (UCSC) consists of a bifacial solar cell coupled to a spectral upconverter. This configuration has been suggested as a means of achieving solar cell efficiency beyond the Shockley-Queisser limit. In this paper an extended model of a UCSC is presented. This model adds to the capabilities of previously-reported models by considering a) non-radiative recombination; b)...
Germanium is an important material for today's highest efficiency solar cells with three np-junctions based on GaInP, GaInAs and Ge. The Ge subcell in these structures consists of a 100–300 nm thin diffused n-type emitter passivated with GaAs or GaInP and a 150 μm thick base layer which is not passivated. Therefore, the current generation of the Ge subcell mainly results from the emitter and covers...
The chemical and electronic structure of high-efficiency chalcopyrite thin film solar cell absorbers significantly differs between the surface and the bulk. While it is widely accepted that the absorber surface exhibits a Cu-poor surface phase with increased band gap (Eg), a direct access to the crucial information of the depth-dependency of Eg is still missing. In this paper, we demonstrate that...
Flexible high barrier materials are needed for the use of future PV module technologies. R2R processes play a key roll for the production of e.g. a-Si, μc-Si, CIS, CIGS or CdTe modules. The requirements for such flexible high barrier materials are very demanding. Permeation values as low as 10−5 g/m2 day for water vapor transition (WVTR) and respectively 10−5 cm3/m2 day atm for oxygen transition (OTR)...
Silicon Solar photovoltaic (PV) industry has maintained sustained growth rates over last 15 years and the future outlook appears to be even brighter considering continuously rising oil prices and ensuing environmental concerns. Most of this growth has been confined to economically advanced countries, tied to grid-connected applications based on government subsidies. In order to meet rising demands,...
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