Showing papers on "Photovoltaic system published in 1999"

Photovoltaic Technology: The Case for Thin-Film Solar Cells

Abstract: The advantages and limitations of photovoltaic solar modules for energy generation are reviewed with their operation principles and physical efficiency limits. Although the main materials currently used or investigated and the associated fabrication technologies are individually described, emphasis is on silicon-based solar cells. Wafer-based crystalline silicon solar modules dominate in terms of production, but amorphous silicon solar cells have the potential to undercut costs owing, for example, to the roll-to-roll production possibilities for modules. Recent developments suggest that thin-film crystalline silicon (especially microcrystalline silicon) is becoming a prime candidate for future photovoltaics.

Development of a photovoltaic array model for use in power-electronics simulation studies

Abstract: To be able to develop a complete solar photovoltaic power electronic conversion system in simulation, it is necessary to define a circuit-based simulation model for a PV cell in order to allow the interaction between a proposed power converter (with its associated control arrangement) and the PV array to be studied. To do this, it is necessary to approach the modelling process from the perspective of power electronics; that is to define the desired overall model in terms of the manner in which the electrical behaviour of the cell changes with respect to the environmental parameters of temperature and irradiance. The authors cover the development of a general model which can be implemented on simulation platforms such as PSPICE or SABER and is designed to be of use to power electronics specialists. The model accepts irradiance and temperature as variable parameters and outputs the I/V characteristic for that particular cell for the above conditions.

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

Photovoltaic Systems Engineering

Abstract: Background.- The Sun.- Introduction to PV Systems.- PV System Examples.- Cost Considerations.- Mechanical Considerations.- Stand-Alone PV Systems.- Utility Interactive PV Systems.- Externalities and Photovoltaics.- The Physics of Photovoltaic Cells.- Present and Proposed PV Cells.

Probabilistic performance assessment of autonomous solar-wind energy conversion systems

Abstract: This paper describes the development of a general probabilistic model of an autonomous solar-wind energy conversion system (SWECS) composed of several wind turbines (wind farm), several photovoltaic (PV) modules (solar park), and a battery storage feeding a load. The model takes into consideration outages due to the primary energy fluctuations and hardware failure. It allows the simulation of wind farms and solar parks containing either identical or different types of wind turbines and PV modules with the load being fed from either the renewable sources, or the battery storage, or both. A methodology is also presented to determine an upper limit on the size of the battery storage required to satisfy a given load profile taking into consideration the charging/discharging of the batteries.

An axial-flux permanent-magnet generator for a gearless wind energy system

Abstract: The paper discuses the development of an axial-flux permanent-magnet generator for a gearless wind energy system which aims to demonstrate the feasibility of integrating wind and photovoltaic energy converters for the generation of electricity and to achieve optimum exploitation of the two energy sources. The merits of an axial-flux generator topology are discussed with reference to the particular requirements of an electrical generator for a direct-coupled wind turbine application. The design, construction and test results of a 5 kW, 200 rev/min permanent-magnet generator, to form a 10 kW pilot power plant with a 5 kW photovoltaic array, are presented.

Origin of Photovoltage and Photocurrent in the Nanoporous Dye-Sensitized Electrochemical Solar Cell

Abstract: The essential role of the dark equilibrium potential is discussed for charge separation and the photovoltaic functioning of the title cell. A quantitative model is presented for the potential distribution in the sponge-type title cell. The unique screening process for the photogenerated electrons is discussed that facilitates their extremely long lifetime since the screening ions cannot function as recombination centers. A general analogy is pointed out for the photovoltaic functioning of the sponge-type electrochemical solar cell and of a conventional single-crystal solid-state solar cell.

New approach to photovoltaic arrays maximum power point tracking

Abstract: The present trend for commercial telecommunication and scientific satellites is the utilization of standard platform, characterized by a high level of flexibility and reduced nonrecurring costs. One of the areas where flexibility is mandatory is the electrical primary power subsystem, due to the impact on solar array configuration and dimensions and on power conditioning unit. Use of the maximum power point tracker (MPPT) concept allows optimization of the above mentioned subsystem, maximizing the power transfer from the photovoltaic generator. The purpose of the paper is to present a new MPPT approach that allows minimization of the drawback caused by the intrinsic capacitance of the photovoltaic array (generally neglected) giving the possibility of operation with a large degree of freedom, independent from the converter topology and photovoltaic power generator, electrical network and technology.

Integrated photovoltaic system

Abstract: An integrated photovoltaic system includes a plurality of individual photovoltaic modules that each convert solar energy into DC power. Each of the photovoltaic modules is coupled to a busway that combines the DC power generated by each photovoltaic module into a DC power output. The connection between each photovoltaic module and the busway is environmentally sealed, as is the electrical wiring contained within the busway. The busway is coupled to a DC to AC power inverter that provides a supply of AC power. The coupling between the busway and the power inverter is environmentally protected, such that the entire DC wiring for the photovoltaic system is environmentally sealed and the system functions as an “AC photovoltaic system” having an AC power output.

A battery management system for stand alone photovoltaic energy systems

Abstract: This paper outlines the development of a battery management system (BMS) for stand alone photovoltaic (PV) energy systems. The BMS calculates the state of charge (SOC) of a lead acid battery to determine the capacity over time. This enables intelligent control schemes to be implemented. A fully functioning prototype was constructed that involved both hardware and software design. Several tests were performed to evaluate the operation of the BMS. The effect of measurement errors on the SOC calculation were subsequently investigated.

A new maximum photovoltaic power tracking control scheme based on power equilibrium at DC link

Abstract: This paper proposes a new simple MPPT (maximum power point tracking) control scheme for A PV (photovoltaic) array based on the principle of power equilibrium at the DC link. In contrast to the typical conventional MPPT scheme based on the so-called mountain climbing method, the proposed scheme needs no detection or calculation of the power and no decision making logic or look up tables, except for several numbers of operational amplifiers. Its operation principle is explained quantitatively. In order to confirm the availability of the scheme, a simulation study using general purpose circuit simulation software PSIM and an experiment have been carried out. Although the stability study and system design are left for future study, the validity of the proposed new MPPT method has been clarified through the simulation and experimental results.

Performance analysis of a hybrid photovoltaic/thermal (PV/T) collector with integrated CPC troughs

Abstract: In the present investigation a theoretical analysis has been presented for the modelling of thermal and electrical processes of a hybrid PV/T air heating collector coupled with a compound parabolic concentrator (CPC) In this design, several CPC troughs are combined in a single PV/T collector panel The absorber of the hybrid PV/T collector under investigation consists of an array of solar cells for generation of electricity, while collector fluid circulating past the absorber provides useful thermal energy as in a conventional flat plate collector In the analysis, it is assumed that solar cell efficiency can be represented by a linear decreasing function of its temperature Energy balance equations have been developed for the various components of the system Based on the developed analysis, both thermal and electrical performance of the system as a function of system design parameters are presented and discussed Results have been presented to compare the performance of hybrid PV/T collector coupled with and without CPC Copyright © 1999 John Wiley & Sons, Ltd

Fuzzy optimisation based control of a solar array system

Abstract: The authors describe the analysis, modelling and implementation of a fuzzy based photovoltaic peak power tracking system. The maximum power of a photovoltaic system changes with temperature, solar intensity and load. An analytical model is built for the solar cell on the basis of the manufacturer's characteristics. The solar panel is integrated with the converter model and a fuzzy algorithm is developed, so as to perform an online search procedure to track the maximum power continuously. The system is implemented by an inexpensive RISC microcontroller. Experimental results have shown excellent performance, robustness with parameter variation and modularity for parallel operation at higher power. The system is ready and easy to fit into existing installations.

Analysis of the effects of a passing cloud on a grid-interactive photovoltaic system with battery storage using neural networks

Abstract: In this paper, a combined radial-basis-functions (RBF) and backpropagation network is used to predict the effects of passing clouds on a utility-interactive photovoltaic (PV) system with battery storage. Using the irradiance as input signal, the network models the effects of random cloud movement on the electrical variables of the maximum power point tracker (MPPT) and the variables of the utility-linked inverter over a short period of time. During short time intervals, the irradiance is considered as the only varying input parameter affecting the electrical variables of the system. The advantages of artificial neural network (ANN) simulation over standard linear models is that it does not require the knowledge of internal system parameters, involves less computational effort, and offers a compact solution for multiple-variable problems. The model can easily integrated into a typical utility system and resulting system behavior can be determined. The viability of the battery-supported PV power system as a dispatchable unit is also investigated. The simulated results are compared with the experimental results captured during cloudy days. This model can be a useful tool in solar energy engineering design and in PV-integrated utility operation.

Solar cell module having an overvoltage preventive element and sunlight power generation system using the solar cell module

Abstract: A solar cell module in which a plurality of photovoltaic elements are installed such that they are electrically connected with each other, wherein an overvoltage preventive element is electrically connected to each photovoltaic element in parallel connection, and the overvoltage preventive element exhibits a one-way continuity and has a minimum operating voltage which is smaller than an open-circuit voltage of the photovoltaic element and is greater than an optimum operating voltage of the photovoltaic element. A sunlight power generation system comprises the solar cell module and an inverter.

Inverter integrated instrumentation having a current-voltage curve tracer

Abstract: An inverter includes a first switch to disconnect an output of the inverter from any device connected thereto, a second switch to disconnect and connect an input of the inverter from direct current fed to the inverter, and a discharge device to discharge any residual charge on a large capacitor. The inverter further includes a voltage sensor to measure input DC voltage to the inverter, a current sensor to measure input DC current to the inverter and a data recorder to provide a current voltage trace to provide a current-voltage curve tracer to provide current-voltage properties of the solar array to which the inverter is attached. The inverter is capable of reproducibly operating at the same point on a module IV curve for a given set of temperature and irradiance conditions. By coupling a temperature sensor to the inverter, photovoltaic module temperature can be measured and combined with the data from the input DC current and voltage sensors and information on the photovoltaic module operating characteristics to compute solar plane-of-array irradiance. Also described is a method for ascertaining photovoltaic module temperature by combining irradiance data, input DC current and voltage measurements and the knowledge that the inverter is operating at a known point on an IV curve. The inverter also includes AC current and voltage sensors for computing inverter output total harmonic distortion.

Validation of a Photovoltaic Module Energy Ratings Procedure at NREL

Abstract: The procedure determines the energy production of a PV module for five reference days. The reference days represent possible operating environments and are qualitatively described as Hot Sunny, Cold Sunny, Hot Cloudy, Cold Cloudy, and Nice. Based on statistical weather criteria, these days were selected from the National Solar Radiation Database (NSRDB). Besides the hourly solar radiation and meteorological data from the NSRDB, the reference days include air mass, angle of incidence, plane of array, and spectral irradiance for a south-facing PV module at latitude tilt, battery-charging voltage, and parameters f1 and f2 for determining PV module temperature. Indoor I-V curve measurements over a range of temperatures and irradiances characterize the electrical performance of a PV module and are used to determine factors to correct for non-linear performance when irradiance and temperature vary. They also serve as a matrix of reference I-V curves for translating to reference-day condition s. The sensitivity of a PV module to variations in the spectral distribution of the incident radiation is accounted for by using an incident irradiance. Differences in PV module thermal characteristics are accounted for by using a PV module's installed nominal operating cell temperature (INOCT) for input to the Fuentes temperature model.more » The procedure does not consider radiation and transmittance losses at large incident angles. These losses were judged too small, and not sufficiently different, for various PV modules to justify the complexity of their measurement and inclusion in the procedure. PV performance measurements from NREL's Outdoor Test Facility during calendar-year 1998 were used to validate the procedure by comparing modeled and measured maximum power values for seven flat-plate PV modules representing different technologies. On an annual basis, modeled values compared within 5% of measured values. Taking into account reproducibility errors from ratings being performed by different facilities and the modeling errors, the following statement applies to the ability of this procedure to show relative differences in the energy production of two PV modules: ''Because of errors in measurements and energy rating methodology, differences of 8% or less in the energy ratings of two PV modules are not significant. If one of the PV modules is amorphous silicon, differences of 13% or less in the energy ratings of two PV modules are not significant.'' This work was performed to develop and validate a PV module energy rating procedure for incorporation into IEEE PAR1479, ''Recommended Practice for the Evaluation of Photovoltaic Module Energy Production.''« less

Photovoltaic solar module in a plate form

Abstract: In a photovoltaic solar module in plate form with an outer plate, an inner plate and a plastic interlayer joining them, in which are embedded solar cells, where the solar cells are interconnected with one another electrically be means of several connecting conductors and where the connecting conductors are each connected so as to be electrically conductive to a connection device arranged in an opening in the inner plate, several connecting conductors are durably connected to a common connection device, which comprises a multiple plug-and-socket connector.

A wireless near-infrared energy system for medical implants

Abstract: A less invasive method for supplying light power to implant devices, we propose a new wireless energy source that employs a near-infrared laser with a photovoltaic cell. The system can also be used with a rechargeable battery. We discuss the configuration of the system, show its energy transfer efficiency, and discuss its performance during some basic experiments.