Showing papers on "Photovoltaic system published in 1983"

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

Dynamic Behavior of a Class of Photovoltaic Power Systems

Abstract: An important consideration in the operation of grid connected photovoltaic power systems is a means of adjusting the photovoltaic array voltage so that maximum output power is achieved for the given atmospheric conditions. The dynamic behiavior of a specific photovoltaic power system which utilizes the well known perturb and observe method of power tracking is examined. Using measured insolation data, it is demonstrated that the perturb and observe method of control migrates considerably from peak power whenever the insolation varies randomly as a result of cloud cover. An alternate method of power tracking is also examined. It is shown that the photovoltaic power system, utilizing the proposed method of power tracking, is able to track accurately peak power conditions during periods of randomly varying insolation.

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.

Photovoltaic-storage battery device

Abstract: A photovoltaic-storage battery device is disclosed, which comprises a substrate having a pair of major surfaces, a photovoltaic element formed on one major surface of the substrate and including a pair of opposing electrodes and a photoelectric film intervening between the pair of opposing electrodes and a storage battery element formed on the other major surface of the substrate and including a second pair of opposing electrodes which are connectable to the first-mentioned pair of opposing electrodes, respectively, and an electrolyte intervening between the second-mentioned pair of opposing electrodes.

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.

A Preliminary Study of Solar Powered Aircraft and Associated Power Trains

Abstract: The feasibility of regeneratively powered solar high altitude powered platform (HAPP) remotely piloted vehicles was assessed. Those technologies which must be pursued to make long duration solar HAPPs feasible are recommended. A methodology which involved characterization and parametric analysis of roughly two dozen variables to determine vehicles capable of fulfilling the primary mission are defined. One of these vehicles was then conceptually designed. Variations of each major design parameter were investigated along with state-of-the-art changes in power train component capabilities. The midlatitude mission studied would be attainable by a solar HAPP if fuel cell, electrolyzer and photovoltaic technologies are pursued. Vehicles will be very large and have very lightweight structures in order to attain the combinations of altitude and duration required by the primary mission.

Future technological applications of rare-earth-doped materials

Abstract: The possible uses of rare-earth-doped glasses or crystals are discussed in connection with (a) luminescent solar concentrators (LSCs), (b) light sources for fibre optics and (c) glass lasers. LSCs can be made from glasses which absorb the major part of the solar spectrum and concentrate the emitted fluorescence at wavelengths to which the photovoltaic cells are most sensitive. The ways in which such glasses can be prepared using a combination of UO 2+ 2 or Cr 3+ with Nd 3+ and Yb 3+ are discussed. An economical analysis of the new type of collector is given. The use of Er 3+ in fluoride glasses for fibre waveguide sources is outlined and recent results are presented. References are made to new laser materials based on Er 3+ and Ho 3+ .

Source Reliability in a Combined Wind-Solar-Hydro System

Abstract: This paper describes the simulation of a combined wind-solar- hydro system for electric power generation, with energy storage facilities. A simple multivariable weather model, including the wind speed, the solar radiation and the rainfall, was developed. This model is * used with the Monte Carlo simulation method to evaluate the reliability of the mixed generating system. Different percentages of wind and solar generation capacities were tried as well as the tilt of the solar arrays.

Source reliability in a combined wind-solar-hydro system

Abstract: This paper describes the simulation of a combined wind-solar- hydro system for electric power generation, with energy storage facilities. A simple multivariable weather model, including the wind speed, the solar radiation and the rainfall, was developed. This model is * used with the Monte Carlo simulation method to evaluate the reliability of the mixed generating system. Different percentages of wind and solar generation capacities were tried as well as the tilt of the solar arrays.

Solar tracking unit

Abstract: A solar tracking system having particular utility for insuring that a relatively lightweight solar collector is properly positioned with respect to the sun. A parabolic reflector surface is included to provide a line of focus of the sunlight directed toward a cylindrical energy absorption tube. Photovoltaic cells provided on either side of the energy absorption tube are directed toward the parabolic reflector surface. A reversible motor is electrically connected to the cells and physically connected to the reflector system for correcting any misalignment with respect to the sun. The reversible motor can be used as the sole means for powering the tracking system or can be used in conjunction with an outside power source.

Sun tracking by peak power positioning for photovoltaic concentrator arrays

Abstract: This paper details the design, development, and evaluation of a microcomputer-based solar tracking and control system (TACS) capable of maintaining the peak power position of a photovoltaic (PV) array by adjusting the load on the array for maximum efficiency and changing the position of the array relative to the sun. At large PV array system installations, inverters are used to convert the dc electrical output to ac for power grid compatibility. Adjustment of the inverter or load for maximum array output is one function performed by the tracking and control system. Another important function of the system is the tracking of the sun, often a necessity for concentrating arrays. The TACS also minimizes several other problems associated with conventional shadow-band sun trackers such as their susceptibility to dust and dirt that may cause drift in solar alignment. It also minimizes effects of structural warpage or sag to which large arrays may be subject during the day. Array positioning is controlled by a single-board computer used with a specially designed input/output board. An orderly method of stepped movements and the finding of new peak power points is implemented. This maximum power positioning concept was tested using a small two-axis tracking concentrator array. A real-time profile of the TACS activity was produced and the data analysis shows a deviation in maximum power of less than 1% during the day after accounting for other variations.

Assessment of flywheel energy storage for spacecraft power systems

Abstract: The feasibility of inertial energy storage in a spacecraft power system is evaluated on the basis of a conceptual integrated design that encompasses a composite rotor, magnetic suspension, and a permanent magnet (PM) motor/generator for a 3-kW orbital average payload at a bus distribution voltage of 250 volts dc. The conceptual design, which evolved at the Goddard Space Flight Center (GSFC), is referred to as a Mechanical Capacitor. The baseline power system configuration selected is a series system employing peak-power-tracking for a Low Earth-Orbiting application. Power processing, required in the motor/generator, provides a potential alternative configurations that can only be achieved in systems with electrochemical energy storage by the addition of power processing components. One such alternative configuration provides for peak-power-tracking of the solar array and still maintains a regulated bus, without the expense of additional power processing components. Precise speed control of the two counterrotating wheels is required to reduce interaction with the attitude control system (ACS) or alternatively, used to perform attitude control functions. Critical technologies identified are those pertaining to the energy storage element and are prioritized as composite wheel development, magnetic suspension, motor/generator, containment, and momentum control. Comparison with a 3-kW, 250-Vdc power system using either NiCd or NiH2 for energy storage results in a system in which inertial energy storage offers potential advantages in lifetime, operating temperature, voltage regulation, energy density, charge control, and overall system weight reduction.

Recent advances in amorphous silicon solar cells and their technologies

Abstract: A review is given on recent advances of amorphous silicon solar cells and their technologies. Firstly, some unique advantages of amorphous silicon as a low cost solar cell material are pointed out in views of basic physics and practical technologies. Secondly, some new approaches to improve photovoltaic performances by utilization of optical and carrier confinement effects with combinations of higher and lower energy gap materials such as a-SiC, μc-Si and a-SiGe, poly c-Si are introduced. In the final part, recent aspects of the industrializations and application field are overviewed.

Applications of ethylene vinyl acetate as an encapsulation material for terrestrial photovoltaic modules

Abstract: Terrestrial photovoltaic modules must undergo substantial reductions in cost in order to become economically attractive as practical devices for large scale production of electricity. Part of the cost reductions must be realized by the encapsulation materials that are used to package, protect, and support the solar cells, electrical interconnects, and other ancillary components. As many of the encapsulation materials are polymeric, cost reductions necessitate the use of low cost polymers. The performance and status of ethylene vinyl acetate, a low cost polymer that is being investigated as an encapsulation material for terrestrial photovoltaic modules, are described.

A study of ultra-thin CuxS-CdyZn1-yS polycrystalline solar cells

Abstract: The study of ultra-thin polycrystalline thin films for use in solar cells is an area of significant research importance because of the low cost of materials. This advantage, however, is often off-set by the rather complex structural properties resulting in inferior photovoltaic performance. This work examines the effects of substrate film thickness of CuxS-CdyZn1-yS chemically sprayed thin film solar cells and analyses the results based on a simple structural model previously proposed by Kwok (1978). It was observed that for cells made on very thin substrates, leakage effect apparently dominated the photovoltaic characteristics resulting in rather low photovoltaic outputs. When the film thickness was increased to above 4.5 mu m, the cell properties were mostly influenced by the junction profile and the surface properties. This would result in a significantly reduced open-circuit voltage. Both effects were apparently structure dependent.

Polymers in Solar Energy Utilization

Abstract: This book is based on a symposium cosponsored by the ACS Divisions of Organic Coating and Plastics Chemistry and Polymer Chemistry at the 183rd Meeting of the American Chemical Society, Las Vegas, Nevada, March 20-April 2, 1982. The authors consider the use of polymeric materials in various methods of solar energy utilization. The book is arranged in three sections: general solar applications, polymer photodegradation in solar applications, and photovoltaic and related applications.

Economic Evaluation of Photovoltaic Generation Applications in a Large Electric Utility System

Abstract: This paper describes the methodology used for and the results obtained from a study to assess the economic viability of long-range applications of photovoltaic (PV) generation in a large eastern electric utility system. Amorphous silicon PV technology, which has been under development by RCA Laboratories since 1974 and formed the basis for the conceptual design of a central- station PV power plant, was used in the application study. Traditional utility system planning techniques were applied to determine the capacity and energy values of PV generation. however, the system capacity reliability evaluation and production cost simulation programs; were modified and applied to more accurately account for the time- constrained and intermittent teatures of PV energy output. Statistical and mathematical procedures were developed to utilize the varying daily insolation data and convert them to appropriate patterns of electric energy output. The study results indicate that with respect to a conventional generation alternative, such as combustion turbines of more advanced design, the breakeven capital cost for PV power plants ranges from $1,100 to $1,350 (1982 dollars) per peak kW. The higher the PV capacity penetration, the lower the required breakeven cost.

Passive solar heating

Abstract: In the southeast, there exist many climate zones where heating needs are low to minimal. If designed properly, a passive solar heating system can provide most of a home’s heating needs for much of the heating season. Because the sun is the main source of heat, a passive solar home includes four features that distinguish it from a conventionally heated home: ♦ A method to collect solar energy; ♦ A way of storing that energy; ♦ A system to distribute heat to the living spaces; and ♦ A means for controlling the heat that reaches living spaces. A passive solar home should always be built to meet high energy conservation standards for the region in which it is built. Carefully planning and designing a home to balance the glass and thermal mass storage areas is crucial in the southeast. Otherwise, the house may overheat, underheat, or have undesirable temperature swings.

Estimated Power Quality for Line Commutated Photovoltaic Residential System

Abstract: A residential photovoltaic system using a line commutated inverter is modeled using a single diode model for the solar cells and a four switch model for the inverter. The model predicts power factor and total harmonic distortion as a function of solar radiation, array voltage, inverter output voltage, and inverter filter capacitor and inductor size. The model was run using parameter values appropriate for the John F. Long PV System and the predicted results compared well with measured results from the system. The model shows that improvements in total harmonic distortion are made at the expense of the power factor. The harmonic distortion is least when the inverter is operating at just continuous conduction. The. total harmonic distortion can be kept to less than 0.17 all day if a variable inductor is used in the inverter's input filter.

Limit of concentration under extended nonhomogeneous light sources

Abstract: Static photovoltaic concentrators, which see the sky as an extended distribution of radiance, are analyzed in a general way. The rules for achieving the highest energy on the cell are derived and the appropriate figures of merit are defined. It is concluded that casting increasingly high values of energy on the cell, which would be bifacial, require collecting a lower portion of the total sky energy. The corresponding figures of merit for the concentrators of the CPC family are analyzed, concluding that a better type of concentrator should be developed for photovoltaic applications.

Method and apparatus for determining spectral response and spectral response mismatch between photovoltaic devices

Abstract: An apparatus including a white light and first, second, and third filters through which the white light is transmitted is utilized to sequentially irradiate a solar cell. The light impinging upon the solar cell from the first, second, and third filters has first, second, and third "tristimulus" distributions. The resulting first, second, and third electrical output quantities produced by the solar cell are measured and utilized to compute normalized spectral response coefficients by normalizing each of the electrical output quantities with respect to the sum of the three. First, second, and third response differences are obtained by subtracting the first, second, and third response coefficients from first, second and third response coefficients previously obtained from a reference solar cell. A spectral response mismatch coefficient equal to the square root of the squares of the three response differences is computed and utilized as a measure of the spectral response mismatch between the solar cell and the reference solar cell. On the basis of such computed spectral response mismatch coefficients, solar cells are grouped in ranges that are sufficiently closely matched to be optimally interconnected in individual solar modules. The technique can also be utilized to determine the spectral response of photovoltaic modules in terms of a tristimulus distribution, and the mismatch coefficient between the module and a solar cell and/or another module.

Development of compound parabolic concentrators for solar energy

Abstract: SYNOPSIS The compound parabolic concentrator (CPC) is not a specific collector, but a family of collectors based on a general design principle for maximizing the geometric concentration, C, for radiation within a given acceptance half angle ±θc. This maximum limit exceeds by a factor of 2 to 4 that attainable by systems using focusing optics. The wide acceptance angles permitted using these techniques have several unique advantages for solar concentrators including the elimination of the diurnal tracking requirement at intermediate concentrations (up to ~10x), collection of circumsolar and some diffuse radiation and relaxed tolerances. Because of these advantages, CPC type concentrators have applications in solar energy wherever concentration is desired, e.g., for a wide variety of both thermal and photovoltaic uses. The basic principles of nonimaging optical design are reviewed. Selected configurations for both non-evacuated and evacuated thermal collector applications are discussed with particular empha...

Photovoltaic power regulation system

Abstract: An apparatus for controlling the charge rate and voltage of storage batteries of a solar power generating system using a single voltage regulator module to monitor and control the state of charge of any number of cells of a battery and a number of solar modules.

Discharge characteristics of a simulated solar cell array

Abstract: Measurements of the transient characteristics associated with the discharge of a simulated solar array are presented. A capacitively coupled probe is used to measure the discharge current, and antennas are used to measure the electromagnetic radiation. Discharges were observed at low surface voltages and several modes of discharge were observed. The maximum discharge current is found to be 0.2 A. This value is several orders of magnitude higher than that reported by previous measurements. Experimental evidence suggests that the inverted voltage gradient is a very likely triggering mechanism for solar array discharges.