An improved design of a fully automated multiple output micropotentiometer

This paper describes in details a new design of a fully automated multiple output micropotentiometer (?pot). A prototype has been built at the National Institute for Standards (NIS), Egypt to establish this highly improved AC voltage source in the millivolt range. The new device offers three different outputs covering a wide frequency range from only one outlet. This valuably supports the precise sourcing ranges of low AC voltage at NIS. The design and the operation theory of this prototype have been discussed in details. An automatic calibration technique has been introduced through specially designed software using the LabVIEW program to enhance the calibration technique and to reduce the uncertainty contributions. Relative small AC-DC differences of our prototype in the three output ranges are fairly verified. The expanded uncertainties of the calibration results for the three output ranges have been faithfully estimated. However, further work is needed to achieve the optimum performance of this new device

Evaluation of the PV cell operation temperature in the process of fast switching to open-circuit mode

A procedure for measuring the overheating temperature (ΔT ) of a p-n junction area in the structure of photovoltaic (PV) cells converting laser or solar radiations relative to the ambient temperature has been proposed for the conditions of connecting to an electric load. The basis of the procedure is the measurement of the open-circuit voltage (VO C ) during the initial time period after the fast disconnection of the external resistive load. The simultaneous temperature control on an external heated part of a PV module gives the means for determining the value of VO C at ambient temperature. Comparing it with that measured after switching OFF the load makes the calculation of ΔT possible. Calibration data on the VO C = f(T ) dependences for single-junction AlGaAs/GaAs and triple-junction InGaP/GaAs/Ge PV cells are presented. The temperature dynamics in the PV cells has been determined under flash illumination and during fast commutation of the load. Temperature measurements were taken in two cases: converting continuous laser power by single-junction cells and converting solar power by triple-junction cells operating in the concentrator modules

Solar cell system having alternating current output

A monolithic multijunction solar cell was modified by fabricating an integrated circuit inverter on the back of the cell to produce a device capable of generating an alternating current output. In another embodiment, integrated curcuit power conditioning electronics was incorporated in a module containing a solar cell power supply

Theoretical Limits of Photovoltaics Efficiency and Possible Improvements by Intuitive Approaches Learned from Photosynthesis and Quantum Coherence

In this review, we present and discussed the main trends in photovoltaics with emphasize on the conversion efficiency limits. The theoretical limits of various photovoltaics device concepts are presented and analyzed using a flexible detailed balance model where more discussion emphasize is toward the losses. Also, few lessons from nature and other fields to improve the conversion efficiency in photovoltaics are presented and discussed as well. From photosynthesis, the perfect exciton transport in photosynthetic complexes can be utilized for PVs. Also, we present some lessons learned from other fields like recombination suppression by quantum coherence. For example, the coupling in photosynthetic reaction centers is used to suppress recombination in photocells.Comment: 47 pages, 22 figures. arXiv admin note: text overlap with arXiv:1307.5093, arXiv:1105.4189 by other author

Roadmap on optical energy conversion

For decades, progress in the field of optical (including solar) energy conversion was dominated by advances in the conventional concentrating optics and materials design. In recent years, however, conceptual and technological breakthroughs in the fields of nanophotonics and plasmonics combined with a better understanding of the thermodynamics of the photon energy-conversion processes reshaped the landscape of energy-conversion schemes and devices. Nanostructured devices and materials that make use of size quantization effects to manipulate photon density of states offer a way to overcome the conventional light absorption limits. Novel optical spectrum splitting and photon-recycling schemes reduce the entropy production in the optical energy-conversion platforms and boost their efficiencies. Optical design concepts are rapidly expanding into the infrared energy band, offering new approaches to harvest waste heat, to reduce the thermal emission losses, and to achieve noncontact radiative cooling of solar cells as well as of optical and electronic circuitries. Light–matter interaction enabled by nanophotonics and plasmonics underlie the performance of the third- and fourth-generation energy-conversion devices, including up- and down-conversion of photon energy, near-field radiative energy transfer, and hot electron generation and harvesting. Finally, the increased market penetration of alternative solar energy-conversion technologies amplifies the role of cost-driven and environmental considerations. This roadmap on optical energy conversion provides a snapshot of the state of the art in optical energy conversion, remaining challenges, and most promising approaches to address these challenges. Leading experts authored 19 focused short sections of the roadmap where they share their vision on a specific aspect of this burgeoning research field. The roadmap opens up with a tutorial section, which introduces major concepts and terminology. It is our hope that the roadmap will serve as an important resource for the scientific community, new generations of researchers, funding agencies, industry experts, and investors.United States. Department of Energy (DE-AC36-086038308

Development and study of a dense array Concentration PhotoVoltaic (CPV) system

In the past several years there has been a growing commercial interest in Concentration PhotoVoltaics (CPV) thanks to its promise of low cost electrical power generation. While the technology of CPV using point-focus Fresnel-like optical elements is reaching maturity, the systems based on dense array receivers still need further scientific progress. This thesis explores the field of CPV applied to a parabolic concentrator prototype and to a dense array receiver made of multijunction solar cells. The solar concentrator, completely designed and built at the University of Trento, is characterized, in order to get the illumination distribution on the PV receiver. The non-uniformity in incident flux results in a current mismatch among cells and strongly impacts the system performance. In order to solve this issue, we have proposed a new type of electrical connection by fitting each cell of the array with an individual DC-DC converter. This method is shown to increase the power transfer efficiency with respect to classical series connection, at least for the tested illumination levels and unbalances. The other main problem with dense array systems is the reliability of the PV receiver, with special attention to the high thermal flux to be dissipated. Several types of water-cooled receivers have been built, with different material configurations that were previously studied with 3D thermal modeling. In particular the building of a multi-cell receiver has required the design of the insulation/interconnection between the cells, the tuning of the cell soldering and the realization of front contact connections

Status report on emerging photovoltaics

\ua9 2023 Society of Photo-Optical Instrumentation Engineers (SPIE).This report provides a snapshot of emerging photovoltaic (PV) technologies. It consists of concise contributions from experts in a wide range of fields including silicon, thin film, III-V, perovskite, organic, and dye-sensitized PVs. Strategies for exceeding the detailed balance limit and for light managing are presented, followed by a section detailing key applications and commercialization pathways. A section on sustainability then discusses the need for minimization of the environmental footprint in PV manufacturing and recycling. The report concludes with a perspective based on broad survey questions presented to the contributing authors regarding the needs and future evolution of PV

Vertical-Tunnel-Junction (VTJ) Solar Cell for Ultra-High Light Concentrations (>2000 Suns)

A novel architecture of cell structure tailored to ultra-high (>2000 suns) concentration ratios is proposed. The basic solar cell consists of two p-n junctions connected in series by a highly doped tunnel diode with the metallic contacts located laterally. The tunneling connection allows using direct band-gap semiconductor compounds aiming to optimize the absorption of the spectrum. The performance of the novel architecture is investigated up to ultra-high concentration using TCAD software. Simulations show its viability for developing a new generation of solar cells to increase the potential in terms of efficiency and cost reduction of ultra-high concentrator systems. The solar cell does not show any degradation with concentration and efficiency as high as 28.4% at 15000 suns has been obtained for a preliminary designThe work of E. F. Fernández and F. Almonacid was supported by the Spanish Economy Ministry and FEDER funds under Project ENE2016-78251-R. The work of N. Seoane and A. J. García-Loureiro was supported in part by the Spanish Ministry of Economy and Competitiveness and FEDER funds under Grants TEC2014-59402-JIN and TIN2016-76373-P and in part by the Xunta de Galicia and FEDER funds under Grant GRC 2014/008S