Showing papers on "Solar power published in 1999"

Wind and Solar Power Systems

Abstract: Introduction Industry Overview Incentives for Renewables Utility Perspective References Wind Power Wind in the World The U.S.A. Europe India Mexico Ongoing Research and Development References Photovoltaic Power Present Status Building Integrated pv Systems pv Cell Technologies pv Energy Maps References Wind Speed and Energy Distributions Speed and Power Relations Power Extracted from the Wind Rotor Swept Area Air Density Global Wind Patterns Wind Speed Distribution Wind Speed Prediction Wind Resource Maps References Wind Power System System Components Turbine Rating Electrical Load Matching Variable-Speed Operation System Design Features Maximum Power Operation System Control Requirements Environmental Aspects References Electrical Generator Electromechanical Energy Conversion Induction Generator References Generator Drives Speed Control Regions Generator Drives Drive Selection Cut-Out Speed Selection References Solar Photovoltaic Power System The pv Cell Module and Array Equivalent Electrical Circuit Open Circuit Voltage and Short Circuit Current i-v and p-v Curves Array Design Peak Power Point Operation pv System Components References Solar Thermal System Energy Collection Solar II Power Plant Synchronous Generator Commercial Power Plants References Energy Storage Battery Types of Batteries Equivalent Electrical Circuit Performance Characteristics More on Lead-Acid Battery Battery Design Battery Charging Charge Regulators Battery Management Flywheel Compressed Air Superconducting Coil References Power Electronics Basic Switching Devices AC to DC Rectifier DC to AC Inverter Grid Interface Controls Battery Charge/Discharge Converters Power Shunts References Stand-Alone System pv Stand-Alone Electric Vehicle Wind Stand-Alone Hybrid System System Sizing Wind Farm Sizing References Grid-Connected System Interface Requirements Synchronizing with Grid Operating Limit Energy Storage and Load Scheduling Utility Resource Planning Tool References Electrical Performance Voltage Current and Power Relations Component Design for Maximum Efficiency Electrical System Model Static Bus Impedance and Voltage Regulation Dynamic Bus Impedance and Ripple Harmonics Quality of Power Renewable Capacity Limit Lightning Protection National Electrical Code on Renewable Power Systems References Plant Economy Energy Delivery Factor Initial Capital Cost Availability and Maintenance Energy Cost Estimates Sensitivity Analysis Profitability Index Hybrid Economics References The Future World Electricity Demand to 2015 Wind Future pv Future Declining Production Costs Market Penetration Effect of Utility Restructuring References Further Reading Appendix 1 Appendix 2 Acronyms Conversion of Units Index

Final Report on the Operation and Maintenance Improvement Program for Concentrating Solar Power Plants

Abstract: This report describes the results of a six-year, $6.3 million project to reduce operation and maintenance (O&M) costs at power plants employing concentrating solar power (CSP) technology. Sandia National Laboratories teamed with KJC Operating Company to implement the O&M Improvement Program. O&M technologies developed during the course of the program were demonstrated at the 150-MW Kramer Junction solar power park located in Boron, California. Improvements were made in the following areas: (a) efficiency of solar energy collection, (b) O&M information management, (c) reliability of solar field flow loop hardware, (d) plant operating strategy, and (e) cost reduction associated with environmental issues. A 37% reduction in annual O&M costs was achieved. Based on the lessons learned, an optimum solar- field O&M plan for future CSP plants is presented. Parabolic trough solar technology is employed at Kramer Junction. However, many of the O&M improvements described in the report are also applicable to CSP plants based on solar power tower or dish/engine concepts.

High efficiency and high concentration in photovoltaics

Abstract: In this paper, we present the state-of-the-art of multijunction solar cells and the future prospects of this technology. Their use in terrestrial applications will likely be for concentrators operating at very high concentrations. Some trends are also discussed and we present a cost calculation showing that highly efficient cells under very high concentration would be able to produce electricity at costs competitive with electricity generation costs for some utilities.

Solar power generating device

Abstract: In order to obtain a solar power generating device capable of effectively using power generated by a solar cell, the virtual optimum operating voltage, the MPPT minimum voltage, the MPPT maximum voltage, and the low and high voltage change width switching voltages used when MPPT control is carried out are calculated on the basis of the output voltage of a solar panel immediately before the startup of the inverter circuit in the solar power generating device and the MPPT control is carried out on the basis of each of the calculated voltage values.

Device for testing solar home systems

Abstract: The invention relates to a device for testing solar home systems comprising at least one of each of the following: a photovoltaic solar generator (6), a battery (7), a charge controller (12) and a load (8). According to the invention, connecting means are provided. These enable the device to be connected to the or to each charge controller (12), said charge controller (s) having been uncoupled from the other components (6, 7, 8); to the or each solar generator (6), to the or each battery (7) and to the or each load (8). The device also comprises testing means with which the components (6, 7, 8, 12) can be tested individually and within their typical operational connections to each other in order to determine the parameters and states which are characteristic to the operativeness of the solar home system being tested. Display means for displaying the parameters and states that are tested are also provided. The inventive device enables less qualified employees to reliably test solar power installations with components (6, 7, 8, 12) which are interconnected on an interruptible bridge (5) since the device is easy to connect to the components (6, 7, 8, 12) in their entirety using the connecting means and since the test can be carried out automatically without manual intervention in the connections of the solar power installation.

Thermophotovoltaic and photovoltaic conversion at high-flux densities

Abstract: We first discuss the similarities between generation of electricity using thermophotovoltaic (TPV) and high-optical-concentration solar photovoltaic (PV) devices. Following this, we consider power losses due to above- and below-bandgap photons, and we estimate the ideal bandgap by minimizing the sum of these, for a 6000 K black-body spectrum. The ideal bandgap, based on this approach, is less than that previously predicted, which could have a significant influence on the performance of devices and systems. To reduce the losses, we show that the low-energy photons may be removed from both types of cells and consider the specific case of a back-surface reflector. This approach to the management of waste heat may offer a useful additional tool with which to facilitate the design of high-photon-flux solar cells. In the case of the high-energy photons and the associated problem of thermalization of hot electrons, however, the heat must be removed by other means, and we consider the applicability of microchannel cooling systems. These appear to have the potential to handle thermal loads at least several times those generated by 1000 times concentrators, or by black-body TPV radiators at a temperature of far greater than 1500 K. We go on to consider the management of the very high currents generated in both concentrator TPV and PV systems and discuss the concept of the monolithically integrated minimodule.

Analysis of the Working Process and Mechanical Losses in a Stirling Engine for a Solar Power Unit

Abstract: In this paper a second level mathematical model for the computational simulation of the working process of a 1-kW Stirling engine has been used and the results obtained are presented. The internal circuit of the engine in the calculation scheme was divided into five chambers, namely, the expansion space, heater, regenerator, cooler and the compression space, and the governing system of ordinary differential equations for the energy and mass conservation were solved in each chamber by Euler`s method. In addition, mechanical losses in the construction of the engine have been determined and the computational results show that the mechanical losses for this particular design of the Stirling engine may be up to 50% of the indicated power of the engine.

Solar battery controller and solar power generating device

Abstract: PROBLEM TO BE SOLVED: To provide a solar power generating device having a maximum power point tracking function capable of accurately detecting a maximum power point even when the output power-output voltage characteristic of a solar battery has a plurality of peaks without making the output voltage and output power of the solar battery fluctuate needlessly. SOLUTION: An output power-output voltage characteristic detecting means CD1 provided with a solar battery PV1 having the same environmental condition as a main solar battery PV2 is provided apart from a main generation circuit. Then, an output voltage controlling means CT1 obtains the numerical data of the output power-output voltage characteristic of the battery PV1 for characteristic detection by turning a switch SW on or off and detects a maximum power point. Then, control signals S1a to S1d are given to respective transistors T1 to T4 of a voltage type inverter IV1 so that the main solar battery PV2 can generate a voltage value corresponding to the detected maximum power point.

Power conditioner device for solar power generation

Abstract: PROBLEM TO BE SOLVED: To enable a stable start operating and increase a power generating time and total generated energy. SOLUTION: The solar cell 32 of a power conditioner device supplies power to an AC power supply 51 via a DC power supply circuit 33, an inverter circuit 34 and a filter circuit 35. At the time of start, a control circuit 37 sets a reference voltage VD1* in accordance with the output voltage VD1 of the solar cell 32, sets a reference current ID1* in accordance with the reference voltage VD1* and the output voltage VD1 so as to limit the reference current ID1* within the range of a reference current upper limit ID1max, and controls the DC power supply circuit 33 in accordance with the reference current ID1*. As the start operation is practiced in accordance with the actual output voltage VD1, power supply loss does not occur and a stable operation can be practiced. Further, even if the output voltage VD1 is lowered by the fluctuation of insolation, as the excessive reference current is not set, the power loss during the starting operation can be avoided.

Solar battery modules, installation method thereof, and solar power generator using such modules

Abstract: A solar battery module and its installation method are provided which are good in installation workability, which can shorten a cable, and can match various roof shapes. A distance between an output terminal and the end face of a solar battery module along a line between output terminals of adjacent solar modules is longer upon installation completion of the adjacent solar battery modules than during electrical connection of the adjacent solar battery modules.

Direct-current power output device and solar power generation system

Abstract: PROBLEM TO BE SOLVED: To suppress variation in reverse tidal-current power to a system by allowing a control means to switch and control the charging and discharging of a charging and discharging means by comparing the output of a DC power source with its target value. SOLUTION: A charging and discharging control part 5 is provided at a halfway part of a branch wire 9 to control the charging and discharging of a charging and discharging element 6. Namely, a switching command part of the charging and discharging control part 5 makes a switching judgement between charging operation and discharging operation according to output power information on a solar battery 1 of a DC collection box 2 which is supplied from a power sensor 10 provided between an intermediate point 8a and the output terminal 2a of the DC collection box 2 and switches the charging and discharging switching part 51 according to the judgement. Consequently, variation in the generated power of the DC power source due to variation of the sunshine is absorbed, so that the variation of the reverse tidal-current power to the system can be suppressed.

Solar sail for power generation

Abstract: The space-based solar power generating system is comprised of a flexible thin film photovoltaic sheet supported as a sail in the solar wind. The solar wind provides pointing support, deployment support, and structure stiffness without a heavy backup structure. A high Isp electric propulsion system is used to counteract the force exerted on the sail by the solar wind.

800 hours of operational experience from a 2 kWe Solar Dynamic system

Abstract: From December 1994 to September 1998, testing with a 2 kW(sub e) Solar Dynamic power system resulted in 33 individual tests, 886 hours of solar heating, and 783 hours of power generation. Power generation ranged from 400 watts to over 2 kW(sub e), and SD system efficiencies have been measured up to 17 per cent, during simulated low-Earth orbit operation. Further, the turbo-alternator-compressors successfully completed 100 start/stops on foil bearings. Operation was conducted in a large thermal/vacuum facility with a simulated Sun at the NASA Lewis Research Center. The Solar Dynamic system featured a closed Brayton conversion unit integrated with a solar heat receiver, which included thermal energy storage for continuous power output through a typical low-Earth orbit. Two power conversion units and three alternator configurations were used during testing. This paper will review the test program, provide operational and performance data, and review a number of technology issues.

Financing solar thermal power plants

Abstract: The commercialization of concentrating solar power technology took a major step forward in the mid 1980s and early 1990s with the development of the SEGS plants in California. Over the years they have proven that parabolic trough power technologies are the most cost-effective approach for commercial scale solar power generation in the sunbelt countries of the world. However, the question must be asked why no additional solar power plants have been build following the bankruptcy of the developer of the SEGS projects, LUZ International Limited. Although many believe the SEGS projects were a success as a result of parabolic trough technology they employ, in truth, the SEGS projects were developed simply because they represented an attractive opportunity for investors. Simply stated, no additional projects have been developed because no one has been able to put together a similarly attractive financial package to potential investors. More than $1.2 billion in private capital was raised in debt and equity financing for the nine SEGS plants. Investors and bankers who make these investments are the real clients for solar power technologies. They are not interested in annual solar to electric efficiencies, but in risk, return on investments, and coverage ratios. This paper will take a look at solar power projects from the financier’s perspective. The challenge in moving forward is to attract private investors, commercial lenders, and international development agencies and to find innovative solutions to the difficult issues that investment in the global power market poses for solar power technologies.

Battery operated air conditioner

Abstract: A new battery opperated air conditioner for providing an air conditioner which may be powered solely upon battery and or battery and solar power in conjunction with alternating current power. The inventive device includes a conventional air conditioner, a rechargeable battery secured within and electrically connected to the conventional air conditioner, and a solar panel pivotally attached to a rear portion of the conventional air conditioner and electrically connected to the rechargeable battery.

The Potential for Low-Cost Electricity from Concentrating Solar Power Systems

Abstract: Concern over the possibility of global climate change as a result of anthropogenic greenhouse gas buildup in the atmosphere is resulting in increased interest in renewable energy technologies. The World Bank recently sponsored a study to determine whether solar thermal power plants can achieve cost parity with conventional power plants. The paper reviews the conclusions of that study.

Harness solar power with smart power-conversion techniques

Abstract: Charge NiCd or NiMH batteries with solar cells. This circuit extracts the maximum power from a solar array to charge a battery stack. It employs the MAX856 boost converter and MAX982 dual comparator with reference. Additional Information: Quick View Data Sheet for the MAX856 Quick View Data Sheet for the MAX982 Samples and Literature Order Form Technical Support: Power As a power source, the sun offers some impressive advantages over typical battery cells: It generates virtually limitless energy, requires no recharging, and is expected to last for another five billion years or so. Today's more efficient, less expensive solar cells provide a practical means of converting the sun's power into electricity to run our gadgets and gismos (see the appendix, From Photons to Electrons). The only clouds in this otherwise sunny picture are . . . well, clouds. Because they often obscure the sun, it's tough to design a system that can reliably provide power. The output current for typical monocrystalline-silicon solar cells directly depends on the amount of incident sunlight (Figure 1). For example, a typical hobby-grade credit-card-sized silicon cell has an open-circuit voltage of 0.55V. Internal resistance causes a voltage drop as you draw current from the cell; but, as light energy drops below the level necessary to support the output load, the cell currentlimits at an almost constant voltage. For a light level of one full sun (solar irradiance of 1kW/m2), the cell provides a typical short-circuit current of 0.3A.

Solar power generating device

Abstract: PROBLEM TO BE SOLVED: To provide a solar power generating device, which can suppress cost increase and enlargement of a reactor used. SOLUTION: A solar power generating device, which inputs a DC voltage from a solar battery, boosts the voltage by means of a booster section, and generates AC power to a system by converting the boosted DV voltage into an AC output by means of a converter section, is housed in a case 1. The reactor 6 for boosting used for the booster section is arranged on the top side, namely, the downstream side of a reactor 7 for filter used for the converter section.

Solar generating device

Abstract: In order to obtain a solar power generating device capable of effectively using power generated by a solar cell, the virtual optimum operating voltage, the MPPT minimum voltage, the MPPT maximum voltage, and the low and high voltage change width switching voltages used when MPPT control is carried out are calculated on the basis of the output voltage of a solar panel immediately before the startup of the inverter circuit in the solar power generating device and the MPPT control is carried out on the basis of each of the calculated voltage values.

Techniques and Applications of Fuzzy Logic Control of Solar Power Plants

Abstract: Publisher Summary This chapter discusses the techniques and applications of fuzzy logic control of solar power plants. The chapter presents different designs of fuzzy logic controllers (FLCs) and applications to the ACUREX distributed solar collector field of the Plataforma Solar de Almeria (Spain). The chapter presents two approaches to automatically design the FLC. The first approach uses data obtained from manual and automatic control operation to automatically obtain the nonlinear control mapping that defines the FLC, and the second approach incorporates considerations about the working point in which the system is operating and introduces a FLC automatically designed by means of a genetic algorithm (GA). The chapter includes real tests in the plant, showing the performance achieved with the proposed controllers. The chapter gives a brief description of the distributed solar collector field and presents the experience-based fuzzy logic controller used to control the plant. The chapter also presents the modified design that allows the nonlinear control mapping describing the FLC to be obtained from input/output data measured at the plant.

Solar battery monitoring device

Abstract: PROBLEM TO BE SOLVED: To speedily detect an abnormality of a solar battery panel. SOLUTION: Generated (Pn) for every parallel branch at the time of solar power generation system installation is measured by a first measuring part 21, total power (PT) of every generated power measured at the part 21 is calculated by a first total power calculating part 22, and by calculating division Pn/PT of the obtained total power (PT) and the generated power (Pn) for every parallel branch, a coefficient determining part 23 obtains a coefficient (Kn) for every branch. When the operation of a solar power generation system is started later, generated power (PnD) for every parallel branch is measured by a second measuring part 24, and total power (PTD) is calculated by a second total power calculating part 25. A valve multiplying the total power (PTD) obtained by the part 25 and the coefficient (Kn) obtained by the coefficient determining part 23 is compared with the generated power (PnD) measured by the second measuring part 24 by a comparator part 26. At the time of PnD > constant × Kn × PTD, the presence of abnormality at one solar battery panel of the branch is judged and an abnormal signal is outputted from an abnormal signal output part 27.

Method of estimating output power of solar cell and device

Abstract: PROBLEM TO BE SOLVED: To provide an output power estimating device and a method which are capable of accurately estimating the output power of a solar cell or a solar power generating device basing on its installation site. SOLUTION: A correction coefficient which becomes large with the increase in a month average temperature is calculated on the basis of the month average temperature of a site where a solar cell is installed (step S1 to S3). The output power of the solar cell is estimated on the basis of the average quantity of insolation, the calculated correction coefficient, and its rated output power at the site (step S4 and S5). By this setup, the output power of an amorphous silicon solar cell or a solar power generating device can be accurately estimated basing on its installation site.

Viable distributed dish/central plant solar power : Status, new developments, potential

Abstract: Distributed dish central plant systems for electricity generation are an extremely valuable and viable means for providing electricity at small or large scale. Such systems should be considered more seriously due to their many advantages. When the latest developments for large 400m 2 aperture paraboloidal dish collectors (with high efficiency and low cost) are incorporated and combined in suitable arrays feeding central plant, excellent economic potential can arise, sufficent to place such systems at the forefront of solar thermal technologies. Recent studies involving large paraboidal dish arrays (IMWe - 100MWe) feeding central plant have indicated viable system performance for electricity generation and waste heat utilisation. When such units are used with multiple effect desalination plant, desalination costs can be very reasonable if the electricity generated attracts good buy-back terms. Desalination water costs of less than one dollar Australian per kilolitre can be realised for sea water desalination.