Search results for " Photovoltaic"

Solar Nanoantennas energy based characterization

2016

Solar nanoantennas appear a very interesting solution to exploit solar radiation, as a matter of fact, their operating principle allows heat losses to be lessened compared to traditional photovoltaic cells and efficiency to be increased. Anyway, some technological issues are to be overcome. Literature often proposes a characterization by radiation efficiency typical of traditional antennas. Since the aim of solar nanoantennas is to harvest energy, in this paper the most promising devices are characterized by the upper bound of deliverable power density calculated in the whole operating wavelengths range.

THE LIMITING EFFICIENCY OF FOUR-BAND CELLS REVISITED

2014

The limiting theoretical efficiency of four-band solar cells is revisited. In previous work, researchers have looked at the theoretical efficiency of four band cells where the smallest of the three sub-band gaps is closest to the valence band and the largest closest to the conduction band. In this work, limits are calculated also for other possible band configurations. In multi-band cells, photon selectivity can be assured by adjusting the band widths. The present work shows that previous authors have put too rigid constraints on the band structure to achieve spectral selectivity. Relieving these constraints gives a considerably higher limiting efficiency for cells with band width restricti…

Phase conjugation in BaTiO 3 by use of the indirect photorefractive coupling of orthogonally polarized light waves

1998

A phase-conjugate wave is generated when an ordinary (extraordinary) signal wave is mixed with two counterpropagating extraordinary (ordinary) waves in the plane normal to the BaTiO3 polar axis. The photorefractive grating that couples the ordinary and the extraordinary waves appears if the incident waves induce a noticeable conical parametric scattering; this grating is a difference grating of many noisy scattering gratings recorded by means of the usual diffusion-mediated charge transport. For comparable intensities of signal and pump waves this type of nonlinear wave mixing is much more efficient than that which is due to the circular bulk photovoltaic effect.

Electrical Characterization of CdTe pixel detectors with Al Schottky anode

2014

Abstract Pixelated Schottky Al/p-CdTe/Pt detectors are very attractive devices for high-resolution X-ray spectroscopic imaging, even though they suffer from bias-induced time instability (polarization). In this work, we present the results of the electrical characterization of a (4×4) pixelated Schottky Al/p-CdTe/Pt detector. Current–voltage ( I–V ) characteristics and current transients were investigated at different temperatures. The results show deep levels that play a dominant role in the charge transport mechanism. The conduction mechanism is dominated by the space charge limited current (SCLC) both under forward bias and at high reverse bias. Schottky barrier height of the Al/CdTe con…

Plasmonic nanostructures for light trapping in photovoltaic

Metallic nanoparticles (NPs), sustaining localized surface plasmon resonances, are currently of great interest for enhancing light trapping in thin film solar cells. To be directly applicable in the photovoltaic industry, the NPs fabrication needs to be simple, reliable, low-cost and scalable. As such, self-assembly processes are most commonly used, and Ag is the preferred material, due to its high radiative efficiency and low imaginary permittivity⁠. After exploring the correlation between structural and optical properties of Ag NPs fabricated by solid- state dewetting process on various substrates, we identified the fabrication conditions in which desirable NPs are obtained, but we also e…

Outdoor performance of north-facing multicrystalline modules in Southern Norway

2012

The present paper deals with reports on an outdoor performance evaluation of multicrystalline modules facing north in Southern Norway. The relevance of this study is mainly for building integrated systems where some of the facades are in a far from optimum position. The impact of shading on the photovoltaic modules' performance is also evaluated. A dedicated experimental set up has been created to study the PV modules performance under the above mentioned conditions. The results indicate significant power extraction from the PV modules even in the north facing direction. Effects of shadowing are also considered.

Power dispatching techniques as a finite state machine for a standalone photovoltaic system with a hybrid energy storage

2020

Standalone photovoltaic system (SPVS) is usually embedded with an energy storage unit to overcome the intermittency of photovoltaic (PV) generation as well as to address load variations in off-grid operation. In SPVS energy systems, batteries can serve as the long term energy storage and contributing to the large portion of the energy demand but to overcome the load intermittency, it necessitates a fast response energy storage embedded with the battery as a hybrid energy storage (HES) for dynamic loads (e.g., Electric Vehicle loads, emergency power management). In this work, Lead-Acid (LA) battery and supper capacitor (SC) array are used as the HES. HES helps not only in increasing more uti…

Power management of grid-connected photovoltaic inverter with storage battery

2011

With increased penetration of PV generation in the power grid, it becomes necessary to control the PV generation similar to the conventional power sources. Grid-connected PV systems equipped with storage batteries are capable of active power control. PV power generation can be either fed into the grid or stored in the battery. This paper presents a deterministic power management algorithm that uses closed-form approximations derived from analytical loss models. It can be configured to maximize the efficiency or the revenue in a liberalized electricity market. The battery controller emulates an optimum load-line in which the PV power is autonomously shared between the battery and the feed-in…

Hydrogen back-up power system with photovoltaic direct energy transfer regulation and interleaved boost for space applicattions

2012

This work details a power conditioning unit for photovoltaic/hydrogen based energy systems in space applications. The power conversion techniques applied are similar to the ones used on photovoltaic/battery space power systems. A direct energy transfer photovoltaic regulator is devised for feeding two outputs; the first output corresponds to the main unregulated battery bus and the second output sets a power path to feed an electrolyser. A modular fuel cell converter completes the system and operates when photovoltaic energy is not available or load demand exceeds the generated photovoltaic power, providing electrical power from a fuel cell. An ancillary battery, located in the main bus, di…

PV System Design for Off-Grid Applications

2015

Solar photovoltaic (PV) technology has the versatility and flexibility for developing off-grid electricity system for different regions, especially in remote rural areas. While conventionally straight forward designs were used to set up off-grid PV-based system in many areas for wide range of applications, it is now possible to adapt a smart design approach for the off-grid solar PV hybrid system. A range of off-grid system configurations are possible, depending upon load requirements and their electrical properties as well as on site-specific available energy resources. The overall goal of the off-gird system design should be such that it should provide maximum efficiency, reliability and …