Showing papers on "Solar power published in 1991"

Solar power plants : fundamentals, technology, systems, economics

Abstract: This work addresses the uses, advantages and costs of solar power plants, covering insolation - its variability, concentration and efficiency of use - and experimental and theoretical developments in the recently created field of solar-driven chemistry (thermal, quantum or electrical excitation). The authors of the papers in this book write from experience of the industry and describe design aspects of experimental and demonstration plants . The future potential of solar energy is considered, taking into account its non-detrimental impact on the environment.

Microprocessor based automatic Sun tracker

Abstract: A microprocessor-based automatic position control scheme has been designed for controlling the azimuth angle of an optimally tilted photovoltaic flat type solar panel or a cylindrical parabolic reflector to get the illuminating surface appropriately positioned for the collection of maximum solar irradiance. The scheme presented results in considerable saving in power and is independent of the geographical location of the site of erection or temporal variations in environmental parameters.

Platform for the utilization of solar power

Abstract: The invention relates to a platform of the utilization of solar power which makes use of linear concentrators to beam the solar radiation for use in thermal, chemical or photovoltaic solar power converters, in which the azimuthal movement of the sun is followed by rotation about the main axis. The aim of the invention is to ensure an approximately uniform conversion rate of the solar radiation largely independently of the height of the sun while avoiding the use of a twin-axis follower system. The area available for utilizing the solar power is to be used as fully as possible as the aperture area to capture the radiation. According to the invention, a floating pipe (2, 2', 112) forming a torus is fitted as a frame for a horizontally extending planar bearer (3-4) held, by substantially evenly distributed buoyant bodies (13, 36, 46, 64a, 64b, 80b) borne by a liquid, at a vertical distance from solar power converting devices (33, 53, 73, 73', 93, 94b).

Thermal Storage for Solar Power Plants

Abstract: Like any other power plant, solar power plant (SPP) output must satisfy the demands of the utility market. During peak demand periods, kilomwatt-hour prices are high and financial incentives are high for guaranteed supply. Solar plant input is limited by diurnal, seasonal and weather-related insolation changes. In order to cope with these fluctuations, the solar plant input may be packed up by fossil fuels, or the solar changes may be mitigated by a buffering storage system.

Vehicle roof with solar power source and contact device

Abstract: Vehicle roof with at least one cover that, alternatively, closes or at least partially opens an opening in a fixed roof surface of the vehicle, carries a solar power source for supplying power to at least one power consuming device that is separately located from the cover, and with a contact device for producing an electrical connection between the solar power source and the consuming device. The contact device is made as a switch arrangement that incorporates the cover so that the power consuming device is connected to the solar power source in one or more predetermined cover positions and is disconnected from the solar power source in all other cover positions.

Thermal Solar Power Plants Experience

Abstract: In parallel with rising interest in solar power generation, several solar thermal facilities of different configuration and size were built, operated, and evaluated in the last decade and a half. Some of these facilities were of exploratory, first-of-a-kind or demonstration nature, in some cases designed merely as engineering experiments for the purpose of gaining performance and operating data at the subsystem and overall plant level. Most facilities were designed as modest-size experimental or prototype solar power plants (SPP) for producing electricity, in a few cases also for cogenerating thermal energy. Of all solar thermal technologies investigated, SPPs using parabolic trough concentrators were the first to reach sufficient maturity to be constructed on a commercial basis in a favorable regulatory environment. Table 7.1 provides an overview of the facilities built, their aggregate nominal capacity (MWe), and their total collective/reflective area.

Solar power research: a scientometric study of world literature

Abstract: An analysis of the output of the literature scanned in Engineering Index during 1970–84 on solar power research indicates that the growth of the literature had been vigorous after the energy crisis in 1973 till 1982. The number of papers at conferences are quite close to the number of references in journals. The area of solar collectors and solar cells has received maximum attention. Publication output of literature by different countries follows the trend in basic sciences with USA being the major producer. The research activity became global after the energy crisis. Performance of the developed countries is low in some fields of solar power.

Photovoltaic systems based on spectrally selective holographic concentrators

Abstract: A holographic device has been developed that greatly improves the efficiency of solar energy conversion. The single-element hologram focuses light to the side and also spectrally splits it. The output appears as a thin concentrated line, focused perpendicular to the hologram and displaced to the side. Different wavelengths are diffracted, concentrated, and dispersed to different locations on the line which resembles an elegant rainbow in the visible. The hologram lets each of two or more different solar cells absorb only those wavelengths which can efficiently convert to electric power. The device also prevents overheating by diffracting unwanted infrared radiation away from the cells. The side focus eliminates shadow effects, and cooling is easy, since the cells are not cascaded and the heat load is minimal. This novel system is ideal for concentrated, split-spectrum, high efficiency solar power generation.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Solar power generating/storing system

Abstract: PURPOSE:To provide a solar power generating/storing system in which the output can be taken out efficiently from a solar cell and stored in a battery. CONSTITUTION:A solar cell PV is connected with a high capacity capacitor C which can be charged instantaneously with high current through a first charging circuit D1. The high capacity capacitor C is connected with a battery B through a second charging circuit D2 and charged when the output of the solar cell PV increases thus charging the battery B continuously from the high capacity capacitor C even after the output of the solar cell PV dropped. Furthermore, the operation can be switched depending on the conditions, e.g. the load L is fed with power from the solar cell PV when the output therefrom is high, by switching the connection of the load L between the output terminals of the high capacity capacitor C and the battery B.

The greening of detroit

Abstract: The article discusses the new age for auto industry: clean cars. Clean air rules being imposed around the world are forcing the auto industry to nearly stamp out exhaust emissions by revamping internal-combustion engines and developing cleaner-burning gasoline. The next step will be car using alternative fuels, such as natural gas, electricity, solar power, and maybe even hydrogen. The article focusses on three alternative cars: electric, natural gas and methanol; and compares their pluses and minuses with gasoline-powered cars.

Joint EPRI/SERI project to evaluate solar radiation measurement systems for electric utility solar radiation resource assessment

Abstract: A description is presented of a cooperative project of the Electric Power Research Institute (EPRI) and the Solar Energy Research Institute (SERI) to compare several solar radiation measurement systems as options for performing solar radiation resource assessments in a utility's service territory. Preliminary results are given for a six-month field comparison of SERI's measurement systems with two different implementations of the rotating shadowband radiometer concept. >

Incorporating solar electric power into rural electrification programs: a case study of Kenya

Abstract: In recent years, photovoltaic (PV) solar electric technology has matured to the point where solar power is now cost competitive with fossil fuel generators for use in remote, low power (<5 kW) applications. This technology is ideally suited for rural electrification in developing countries due to the high availability of solar insolation and the low power requirements in these regions. Yet PV technology is growing very slowly in Third World nations. This is due to both a lack of awareness of the technology and barriers from several institutions. In this article a case study of Kenya is performed, considering the opportunities for incorporating solar electric power into Kenya's rural electrification programs. The barriers preventing widespread deployment of this technology in Kenya are presented, and ways of overcoming these impediments are suggested.

Plaform for the utilisation of solar power

Abstract: The invention relates to a platform of the utilisation of solar power which makes use of linear concentrators to beam the solar radiation for use in thermal, chemical or photovoltaic solar power converters, in which the azimuthal movement of the sun is followed by rotation about the main axis. The aim of the invention is to ensure an approximately uniform conversion rate of the solar radiation largely independently of the height of the sun while avoiding the use of a twin-axis follower system. The area available for utilising the solar power is to be used as fully as possible as the aperture area to capture the radiation. According to the invention, a floating pipe (2, 2', 112) forming a torus is fitted as a frame for a horizontally extending planar bearer (3-4) held, by substantially evenly distributed buoyant bodies (13, 36, 46, 64a, 64b, 80b) borne by a liquid, at a vertical distance form solar power converting devices (33, 53, 73, 73', 93, 94b).

Mass properties survey of solar array technologies

Abstract: An overview of the technologies, electrical performance, and mass characteristics of many of the presently available and the more advanced developmental space solar array technologies is presented. Qualitative trends and quantitative mass estimates as total array output power is increased from 1 kW to 5 kW at End of Life (EOL) from a single wing are shown. The array technologies are part of a database supporting an ongoing solar power subsystem model development for top level subsystem and technology analyses. The model is used to estimate the overall electrical and thermal performance of the complete subsystem, and then calculate the mass and volume of the array, batteries, power management, and thermal control elements as an initial sizing. The array types considered here include planar rigid panel designs, flexible and rigid fold-out planar arrays, and two concentrator designs, one with one critical axis and the other with two critical axes. Solar cell technologies of Si, GaAs, and InP were included in the analyses. Comparisons were made at the array level; hinges, booms, harnesses, support structures, power transfer, and launch retention mountings were included. It is important to note that the results presented are approximations, and in some cases revised or modified performance and mass estimates of specific designs.

Control-structure interaction study for the Space Station solar dynamic power module

Abstract: The authors investigate the feasibility of using a conventional PID (proportional plus integral plus derivative) controller design to perform the pointing and tracking functions for the Space Station Freedom solar dynamic power module. Using this simple controller design, the control/structure interaction effects were also studied without assuming frequency bandwidth separation. From the results, the feasibility of a simple solar dynamic control solution with a reduced-order model, which satisfies the basic system pointing and stability requirements, is suggested. However, the conventional control design approach is shown to be very much influenced by the order of reduction of the plant model, i.e. the number of the retained elastic modes form the full-order model. This suggests that, for complex large structures, such as the Space Station Freedom solar dynamic, the conventional control system design methods may not be adequate. >

Solar power supply

Abstract: PURPOSE:To drive an electrical load efficiently by driving the electrical load with power generated through a solar generating means and then comparing the operating voltage or current of the electrical load with a reference value thereby controlling a series/parallel switching means. CONSTITUTION:A switching means 24 is driven in response to the operating voltage of an electrical load 23 such as a ventilation fan, such that a plurality of solar cells 21, 22 are connected in series if the operating voltage of the load 23 is higher than the reference value whereas the solar cells 21, 22 are connected in parallel if the operating voltage is lower than the reference value. In other words, series/parallel switching control of the plurality of solar cells 21, 22 is carried out in accordance with the operating voltage of the load 23. Since no extra power supply is required in the switching control, the electrical load 23 such as a ventilation fan can be driven efficiently.

Diode laser power module for beamed power transmission

Abstract: Recent progress with powerful, efficient, and coherent monolithic diode master-oscillator/power-amplifier (M-MOPA) systems is promising for the development of a space-based diode laser power station. A conceptual design of a 50-kW diode laser power module was made for space-based power stations capable of beaming coherent power to the moon, Martian rovers, or other satellites. The laser diode power module consists of a solar photovoltaic array or nuclear power source, diode laser arrays (LDAs), a phase controller, beam-steering optics, a thermal management unit, and a radiator. Thermal load management and other relevant aspects of the system (such as power requirements and system mass) are considered. The 50-kW power module described includes the highest available efficiency of LD M-MOPA system to date. However, the overall efficiency of three amplifier stages, including the coupling efficiency, turns out to be 55.5 percent. Though a chain of PA stages generates a high-power coherent beam, there is a penalty due to the coupling loss between stages. The specific power of the 50-kW module using solar power is 6.58 W/kg.

Comparison of photovoltaics with solar thermal trough electric systems as a central station utility resource in the 1990s

Abstract: The approach and results of work to compare solar thermal parabolic trough systems and photovoltaic systems as utility electric generation resources in the mid-to-late-1990s are discussed. Assumptions, methodology, designs, performance simulation, value analysis, cost estimates, and economic feasibility analysis are presented. Results, based on standard utility financial criteria and avoided costs, show that central station solar power generation is not economically feasible in the 1990s for the case considered. While economic feasibility of troughs occurs in 2004 and somewhat less later for emerging PV options, incorporation of environmental or resource diversification attributes would hasten cost-effectiveness of both technologies. >

Performance enhancement using power beaming for electric propulsion Earth orbital transporters

Abstract: Power requirements for an electric propulsion Earth orbital transport vehicle (EOTV), which can effectively deliver large payloads using much less propellant than chemical transfer methods, are addressed. The power beaming concept is described. Arcjets, magnetoplasmadynamic (MPD) thrusters, and ion engines are covered. Power supply characteristics are discussed for nuclear, solar and power-beaming systems. Operational characteristics are given for each, as are the effects of the power supply alternative on the overall craft performance. Because of its modular nature, the power beaming can meet the power requirements of all three electric propulsion types. Commonality of approach allows different electric propulsion approaches to be powered by means of a single power supply approach. Power beaming exhibits better flexibility and performance than onboard nuclear or solar power systems. >

Solar power steps out of the shadows

Abstract: At the 1982 Versailles meeting of the leaders of the seven major Western countries (the G7 countries), photovoltaics (PV) was identified as one of the major renewable sources of energy for the next century. Since then the technology has advanced dramatically in tandem with a rapid increase in the volume of production for commercial markets. The governments of all the industrialized nations, except the UK, have mounted R&D programmes in photovoltaics which have helped to being about these advances and, in Europe, the Commission of the European Community (CEC) has established very successful programmes in many of its member countries.

Solar-powered aircraft design

Abstract: Beginning with the present state-of-the-art in cost-efficient solar technology, optimization of a solar-powered aircraft has shown possibilities of this new technique. The following developments have improved solar-flight technology: high-precision aircraft construction of minimum weight; integration of the solar cells in the upper wing surface without aerodynamic or other losses; high-efficiency drive and propulsion system with variable pitch propeller, automatically controlled to attain maximum photovoltaic power output; a buffer battery of high power output for safe take-off and difficult flight incidents. All these features have already been successfully tested on a model aircraft. A design proposal will be presented involv­ing a high-efficiency solar powered aircraft with 25m wing­ span capable of taking off and climbing up to an altitude of 450m equipped with a buffer battery. Above this altitude, the aircraft is to fly and climb up further (up to 0.45m/sec.) by solar power alone.

The design and construction of a solar electric commuter car

Abstract: A description is presented of the design and construction of a solar electric commuter car-a practical commuting vehicle whose primary energy source is solar. A Sebring fiberglass kit car on a Volkswagen Beetle chassis was chosen for conversion to an electric vehicle with solar recharging capability. The 1600 lb two-passenger vehicle was equipped with a 25 hp peak DC brushless motor, a 5 kWh battery pack, and a 500 W/sub p/ solar cell array. The car meets the Pennsylvania safety inspection code for a passenger vehicle. Final design details and preliminary performance data are given. >