Showing papers on "Solar energy published in 1983"

Fundamentals of solar cells

Abstract: This text is addressed to upper level graduate students with background in solid state physics and to scientists and engineers involved in solar cell research. The author aims to present fundamental physical principles rather than the state-of-the-art. Specific devices are used to illustrate basic phenomena and to indicate possibilities for innovative design. Contents, abridged: Solar insolation. The calculation of solar efficiency. Silicon solar cells. Heterojunction and heteroface structure cells. Polycrystalline thin films for solar cells. Concentrators, concentrator systems, and photoelectrochemical cells.

Thin Film Solar Cells

Abstract: Why Thin Film Solar Cells?- Basic Physical Processes in Solar Cell Materials- Photovoltaic Behavior of Junctions- Photovoltaic Measurements, Junction Analysis, and Material Characterization- Thin Film Deposition Techniques- Properties of Thin Films for Solar Cells- Cu2S Based Solar Cells- Polycrystalline Thin Film Silicon Solar Cells- Emerging Solar Cells- Amorphous Silicon Solar Cells- Photoelectrochemical Cells- Novel Concepts in Design of High-Efficiency Solar Cells

Modeling of thin film solar cells: Uniform field approximation

Abstract: A model of a p‐i‐n thin‐film solar cell is presented that can be easily used to analyze solar cell properties. The continuity equations are solved using the regional approximation, producing elementary solutions that give insight into the physics of the transport in the cell. The steady‐state solutions are compared with measurements on typical hydrogenated amorphous silicon, a‐Si:H, solar cells. The ac solutions are used to explain a new source of photocapacitance due to mobile carriers.

Global Angular Momentum and Energy Balance Requirements from Observations

Abstract: Publisher Summary This chapter presents an overview of global angular momentum and energy balance requirements deduced through observations. The structure of the basic circulation, the temperature, humidity, and kinetic energy fields, both regarding their long-term mean values and their day-to-day and seasonal variability characteristics, are discussed. Following this, the three-dimensional structure of the transports by the transient eddy, stationary eddy, and mean meridional circulations are explained. The chapter describes how the source regions of incoming solar radiation and the sink regions of outgoing terrestrial radiation are distributed over the globe, and how the atmosphere and oceans respond to these forcing factors. It also explores what happens to the solar energy once it has entered the atmosphere. The storage and transport of energy in the atmosphere is analyzed, followed by a discussion on the amount of energy that flows into the underlying surface. The storage and transport of energy in the oceans is also discussed..

Wavelength-selective absorption enhancement in thin-film solar cells

Abstract: We present the general principle of wavelength‐selective enhancement of absorption in thin‐film solar cells by a periodic grating substrate. By exact numerical calculation we demonstrate that substantial short‐circuit current gains are realizable in thin‐film amorphous silicon (a‐SiHx) solar cells. In particular, for a 0.5‐μm‐thick a‐SiHx solar cell, optimal texturing of an Ag substrate to form a one‐dimensional reflective grating can yield a 2‐mA/cm2 enhancement over the flat substrate case. For a two‐dimensional cross‐hatched grating substrate the enhancement is estimated to be 3.5–4 mA/cm2.

Materials for photothermal solar energy conversion

Abstract: Commencally or potentially available selective and non-selective absorber surfaces for solar heat collectors are reviewed and the state-of-the-art of solar collector corrosion processes is outlined. The review of available published literature has indicated that a lack of quantitative information exists, relative to corrosion of collector surfaces. Available information (mostly qualitative) on durability aspects and corrosion of solar receiver surfaces is described to indicate potential corrosion problem areas and corrosion prevention possibilities. An outline of appropriate durability tests is presented.

Hydrogen passivation of defects in silicon ribbon grown by the edge‐defined film‐fed growth process

Abstract: Electrically active defects in edge‐defined film‐fed grown silicon ribbon solar cells have been passivated using a hydrogen plasma from a Kaufman ion source. Significant improvements in solar cell efficiency for both low diffusion length starting material (∼20 μm) and high diffusion length (∼50 μm) material have been obtained. For the former, passivation has produced solar cell efficiency improvements as high as 41% and in the case of the latter, solar cell efficiencies as high as 14.5% (AM1) have been obtained. Electron beam induced current micrographs are shown which indicate near total defect passivation for at least the top 9 μm of the solar cell.

Hybrid solar/combustion powered receiver

Abstract: An improved hybrid solar/combustion powered receiver, for use e.g. with a hot gas engine, the receiver being of the type having a housing and an aperture for admitting solar radiation to the cavity defined by the housing. The improved receiver includes a heat exchanger within the cavity and having the tubes tangentially spaced; multiple burners for providing a combustion gas flow path during combustion powered operation between and around the portions of the tubes upon which solar radiation impinges; and a fused silica, internally mounted window to seal the aperture against combustion gas leakage out of the receiver.

Efficient and stable solar cell by interfacial film formation

Abstract: The development of a new efficient and stable semiconductor-liquid junction solar cell is reported. The n-CuInSe2/I2-I−-Cu+-HI/C cell utilizes relatively inexpensive, non-toxic components and requires less stringent sealing which makes this cell a more feasible candidate for energy conversion device applications than its predecessors1–3. Initial output power measurements have already yielded a conversion efficiency of 9.5% under AM1 (Air Mass 1) conditions. After passage of 70,000 C cm−2 the cell continues to deliver virtually unchanged photocurrents at maximum power point. The performance is based on the in situ formation of an interfacial film that is stable in the operational range of the solar cell.

The Loss of Power Supply Probability as a Technique for Designing Stand-Alone Solar Electrical (Photovoltaic) Systems

Abstract: Many solar electrical (photovoltaic) systems (SES) are designed and are in operation in many countries. Most of the analysis and design methods are based on the concept of power supply during a number of autonomous days (NAD). This NAD value refers to the number of consecutive days in which no power is supplied to the system from the solar cell array(SCA). The storage system capacity is thus based on the required energy during NAD.

Barrier at the interface between amorphous silicon and transparent conducting oxides and its influence on solar cell performance

Abstract: We have found that a heterostructure made of a conductive transparent oxide (SnO2, ITO, or Pt:SiO2) and p‐type or n‐type or intrinsic a‐Si:H shows a substantial potential barrier at the interface. This barrier is important in order to explain the behavior of Voc versus doping of the p layer in p‐i‐n solar cells. The barrier should also be taken into account in order to explain the poor blue response of solar cells.

Monte Carlo simulation of the performance of PMMA luminescent solar collectors.

Abstract: A Monte Carlo method has been developed to simulate the performance of luminescent solar collectors (LSC) consisting of a PMMA plate with an attached film (or multiple-film stack) of dye-activated PMMA. Rhodamine 6G and Fluorol 555 have been considered as dopant dyes. Direct and diffuse solar spectra have been simulated in order to compare extreme insolation conditions. Efficiency factors have been determined as a function of the main geometrical and optical parameters of the LSC.

Reflective solar tracking system

Abstract: A reflective solar tracking system of the type arranged to reflect light rays from the sun onto a remote solar energy collector is described. The system comprises a reflector mounted on an assembly incorporating a drive mechanism for rotating the reflector about two axes to compensate for altitudinal and azimuthal changes in the position of the sun. A sensor device is adapted to point at the sun and provide control signals to the drive mechanism so that the reflector is moved in response to solar movement such that sunlight is always reflected onto the collector and at the same time the sensor device is moved so as to track the sun.

New types of high efficiency solar cells based on a‐Si

Abstract: Three types of new structure a‐Si solar cells having more than 9% efficiency are presented. The first one has a high optical reflection back electrode metal alloyed with optically transparent n‐type μc‐Si deposited on the conventional glass substrate a‐SiC/a‐Si heterojunction solar cell. The second type structure is an inverted p‐i‐n solar cell having Ag/TiO2/a‐Si metal‐insulator‐semiconductor type back surface electrode which more efficiently collects longer wavelength photocarriers just above the band edge. The third structure demonstrated here has a‐Si/polycrystalline tandem junction to pick up the energy of longer wavelength photons passing through the front side of the a‐Si solar cell. All key technologies proposed here are practical and offer more promised real alternatives for the fabrication of high efficiency a‐Si solar cells.

Solar cell manufacture

Abstract: An improved solar cell, and method for manufacture, in which a back side reverse p-n junction is formed prior to metallization and a gridded back side metallization material, chosen so that it penetrates the p-n junction where it is present, is fired into the wafer. The finished solar cell has improved efficiency despite the presence of the reverse p-n junction over a majority of the back face surface.

Brayton engine burner

Abstract: A heating chamber for supplying heated air in a Brayton engine or gas turbine plant including a compressor and turbine. The heating chamber includes a solar energy receiver that receives solar energy, converts it to heat, and heats air from the compressor. To supply additional energy that may be required for the turbine, fuel is injected into the air stream and a catalyst downstream of the solar receiver reacts the fuel with the air to provide additional energy.

Passive integral solar heat collector system

Abstract: The present invention relates to an improved apparatus for collecting, absorbing, transferring, and storing solar heat energy, economically and passively, without pumps or electric power. The apparatus comprises a solar collector with a flat finned heat pipe absorber and an attached integral insulated storage tank with a double wall heat exchanger. The absorber, made of one or more slightly tilted gravity assisted heat pipes with flat absorber fins, absorbs and transfers solar heat by evaporation, vapor transport, and condensation to the slightly elevated heat storage tank. The one or more heat pipes turn on when the sun is shining and turn off automatically when the sun is not shining.

Selective Optical Surfaces for Solar Energy Converters

Abstract: A review is given of Selective Optical Surfaces for Solar Energy Converters by M.M. Koltun. The book compiles examples of optical multilayer stacks and antireflecting coatings, primarily addresses photovoltaic conversion, and examines efficiencies of A-R coated cells as a function of the number of A-R layers. It notes the selectivity and various other properties of solar cells: the effect of U.V. radiation, thermal cycling, mechanical damage and erosion, angle of incidence of solar radiation, and stability under particle irradiation pertaining to space utilization of cells. Cells discussed are standard silicon or gallium arsenide systems, with no mention of amorphous semiconductors or polysilicon samples.

Method of forming a solar collector or hot water storage tank and solar water heating apparatus using same

Abstract: The present invention relates to a method of forming a solar collector, or absorber, panels or a heat storage tank, suitable for heating water using solar energy. It also relates to articles of manufacture so formed and to solar water heating apparatus using said articles. Three methods of forming the panel or tank from two sheets of uncured elastic material, such as EPDM rubber, by simultaneously bonding and curing such material around the peripheral edges of the two sheets and at spaced apart, discrete areas over most of the interior areas of the sheets. In one form of the method, one of the sheets is coated with a layer of release agent, over all areas except the discrete areas and the peripheral areas so that only such uncoated areas will bond during cure. In another form, a sheet of non-adherent plastic slightly smaller than the two sheets and having holes or holidays to form the discrete areas is bonded between the two sheets. In a third form, the peripheral edges are first sealed to form a chamber, then the chamber is inflated and a forming die presses together the discrete areas only. Preferably, but not necessarily, reinforcing fibers may be employed or molded, into at least one of the uncured sheets. As articles of manufacture the absorber, or tank, each includes at least one inlet and one outlet at opposed edges of the so formed chamber. Further, the storage tank has a portion of the enclosed volume adapted to receive a heat exchanger. This is made possible by omission of the discrete bonded areas over about one-fourth of the area to the two sheets. In apparatus form, a solar absorption panel and a storage tank so formed (and interconnected inlet to outlet) are mounted back-to-back by an enclosing structure suitable for roof-top or ground-pad mounting and connection into a water system for solar heating of domestic water.

Pulse anneal method for solar cell

Abstract: A solar cell including a pulse annealed layer of crystalline, amorphous or polycrystalline semiconductor material of one conductivity type and either a layer of opposite conductivity type or a liquid electrolyte forming a collector junction therewith. A method of improving the characteristics of a solar cell including at least one layer of crystalline, amorphous or polycrystalline semiconductor material which includes the step of pulse annealing said semiconductor material.

Transient response of latent heat storage in greenhouse solar system

Abstract: A latent heat storage system with two different stacking configurations and air bafflings was designed and constructed as an integrated part of the greenhouse solar system. Commercial cylindrical storage rods were used as the primary storage elements. The results showed that the latent storage system performed significantly better than water or rock storage.