Showing papers on "Photovoltaic system published in 1987"
TL;DR: In this article, a photoelectrochemical solar cell (PEC) with in situ storage, operating at 11.3% overall solar to electrical conversion efficiency, with a generated power insensitive to daily fluctuations in solar radiation.
Abstract: We report a photoelectrochemical solar cell (PEC) with in situ storage, operating at 11.3% overall solar to electrical conversion efficiency, with a generated power insensitive to daily fluctuations in solar radiation. A primary advantage of PECs, compared to photovoltaic solar cells, had been their proposed capacity for in situ storage by the addition of a single electrochemical half cell1. Several systems combining photoelectrochemical conversion with electrochemical storage have been presented with maximum efficiencies of approximately 3 per cent. A series of polysulphide solution effects2–5 resulted in a high efficiency caesium polysulphide n-Cd(Se,Te) single crystal PEC6. As will be shown, this leads to an autonomous cell with sufficient voltage to bypass the previous necessity for bipolar dual photoelectrode storage, allowing single photoelectrode induced electrochemical storage, with a high continuous output.
128 citations
TL;DR: In this article, the authors present the results of a simulation designed to assess the maximum possible changes in PV generation that a utility can expect over certain time intervals for different service area sizes.
Abstract: As the incident solar radiation on a utility service area changes, the power generated by utility-interactive solar photovoltaic (PV) generators dispersed throughout that area also changes. The utility must follow these changes with its own generation, just as it now follows normal fluctuations in customer load. This paper presents the results of a simulation designed to assess the maximum possible changes in PV generation that a utility can expect over certain time intervals for different service area sizes. The simulation can be used with a power flow program to study the actual effects of dispersed residential PV generation on a utility.
125 citations
TL;DR: In this article, the quality of load matching in a photovoltaic system is defined as the ratio of the load input power to the generator's maximum power as a function of the solar insolation, or as the function of solar time.
Abstract: The quality of load matching in a photovoltaic system determines the quality of system performance and the degree of the solar cells utilization. In a matched system, the operation of the load-line is close to the maximum power-line of the solar cell (SC) generator. Some load-lines inherently exhibit a relatively good matching when they are directly connected to the SC generator; for others, the matching is rather poor, and therefore, requires the inclusion of a maximum-power-point-tracker (MPPT) in the system. This present study deals with the performance analysis of six common types of loads that are directly connected to the SC generator, and defines a factor that describes the quality of matching of the load to the solar cells. The results of the study indicate the compatibility of the different loads when powered by solar cells, and will assist the designer of the photovoltaic system in considering whether to include an MPPT. The quality of load matching is defined here as the ratio of the load input power to the SC generator maximum power as a function of the solar insolation, or as a function of the solar time. The six loads are: an ohmic load, a storage battery, an ohmic load and storage battery, a water electrolyzer, a power conditioner--constant power load, and a dc motor driving volumetric and centrifugal pumps.
114 citations
TL;DR: In this article, conditions for efficiency improvement and optimization in indium-tinoxide/pindium-selenide solar cells are discussed in terms of electrical and photovoltaic properties.
Abstract: Conditions for efficiency improvement and optimization in indium‐tin‐oxide/p‐indium‐selenide solar cells are discussed in this paper. This aim is achieved by using low‐resistivity p‐indium‐selenide and by incorporating a back‐surface‐field contact. This contact is insured by a p‐indium selenide/gold barrier whose rectifying behavior is explained through the complex impurity structure of p‐indium‐selenide. Electrical and photovoltaic properties of the cells are also reported. The efficiency parameters under AM1 simulated conditions have been improved up to 32 mA/cm2 for the short‐circuit current density, 0.58 V for the open‐circuit voltage, and 0.63 for the filling factor. As a result, solar efficiencies larger than 10% in annealed cells and 8% in unannealed ones have been attained. The limitations of these devices are discussed by investigating the dependence of electrical and efficiency parameters in function of photon flux and temperature.
109 citations
TL;DR: In this article, an optimization of a photovoltaic pumping system based on an induction motor driven pump that is powered by a solar array is presented, where the motorpump subsystem is analyzed from the point of view of optimizing the power requirement of the induction motor, which has led to an optimum u-f relationship useful in controlling the motor.
Abstract: The optimization of a photovoltaic pumping system based on an induction motor driven pump that is powered by a solar array is presented in this paper. The motor-pump subsystem is analyzed from the point of view of optimizing the power requirement of the induction motor, which has led to an optimum u-f relationship useful in controlling the motor. The complete pumping system is implemented using a dc-dc converter, a three-phase inverter, and an induction motor-pump set. The dc-dc converter is used as a power conditioner and its duty cycle is controlled so as to match the load to the array. A microprocessor-based controller is used to carry out the load-matching.
100 citations
TL;DR: In this article, an analog-digital photovoltaic array simulator is proposed for the study of transient phenomena associated with the interconnected operation of PVs and the utility grid, where the analog section is designed on the basis of an equivalent solar cell model while the digital section is constructed realizing the mathematical representation of the array.
Abstract: An analog-digital photovoltaic (PV) array simulator is considered. The analog section is designed on the basis of an equivalent solar cell model while the digital section is constructed realizing the mathematical representation of the array. Fast time responses achieved by the analog section make this part suitable for the study of transient phenomena associated with the interconnected operation of PVs and the utility grid. Its digital counterpart is more appropriate for long-term experimental investigations due to its inherent accuracy and reliability. The combined hybrid simulator offers a versatile and flexible piece of apparatus capable of simulating the performance of any PV array under a variety of operating conditions. The device can be constructed with low-cost components in a compact arrangement offering transportability and ease of operation. Experimental results derived from a laboratory constructed prototype match closely the theoretically computed characteristics.
97 citations
TL;DR: The analytic solutions discussed here can bring the price of stand-alone photovoltaic systems to economic viabilty at today's hardware and fuel prices, and can also enable local designers in developing countries to design these systems economically and on their own.
91 citations
Patent•
20 Aug 1987
TL;DR: In this paper, a photovoltaic system controller is presented for utilization with a power system including an auxiliary generator, battery, and an array of solar cells, which is adapted to be easily field adjustable to cover a wide range of parameters.
Abstract: A photovoltaic system controller particularly adapted for utilization with a photovoltaic power system including a photovoltaic array, system battery, load and, optionally, an auxiliary generator. The controller utilizes a microprocessor to monitor various parameters of the system and to perform system control functions. The microprocessor is provided with a plurality of setpoints corresponding to desired system parameters for utilization as reference points for the conducting of control functions. The setpoints are adapted to be easily field adjustable to cover a wide range of parameters. The controller is particularly suited for adaption to an entire spectrum of system designs merely by replacing the programmable memory component of the controller. The controller derives its power from a tap off the system battery and is designed to withstand the harsh environment associated with remote site locations. All of the control functions are temperature compensated. The controller is provided with timing control means which allows the controller to be inactive between operating cycles so as to reduce power requirements.
87 citations
Patent•
26 May 1987TL;DR: A point focus solar concentrator as mentioned in this paper uses various geometries of cylindrical reflector strips some of which are tilted to simulate a point focus by overlaying the line focii of each segment at a coincident point.
Abstract: A point focus solar concentrator which uses various geometries of cylindrical reflector strips some of which are tilted to simulate a point focus by overlaying the line focii of each segment at a coincident point Several embodiments of the invention are disclosed that use cylindrical parabolic, cylindrical hyperbolic or flat reflector strips to concentrate incident solar energy for use by a solar dynamic engine located at the focal point Also disclosed is a combined photovoltaic/solar dynamic engine concentrator energy system that uses this arrangement of mirrors
81 citations
TL;DR: The total life-cycle cost of stand-alone photovoltaic (SAPV) power systems is mathematically formulated and a new optimal sizing algorithm for the solar array and battery capacity is developed.
79 citations
TL;DR: In this paper, the authors derived general expressions for the shading and insolation of a field of solar thermal or photovoltaic collectors, where the shading on a collector may be cast by its neighbour and/or by a fence, and is dependent on the spacing between collectors, and on collector height, row length, tilt angle and latitude location.
TL;DR: In this paper, a microprocessor-controlled static induction transistor (SIT) inverter is proposed to link a solar battery with a utility ac power line, where the main control objectives are to optimize the power flow from the solar battery to the utility power line and to compensate the reactive power, including harmonic distortion.
Abstract: A microprocessor-controlled static induction transistor (SIT) inverter is proposed to link a solar battery with a utility ac power line. The main control objectives are to optimize the power flow from the solar battery to the utility power line and to compensate the reactive power, including harmonic distortion. The performance is well realized by the experimental setup.
Book•
01 Jan 1987
TL;DR: In this paper, the effect of introducing grain boundaries in silicon, the commercial production for multicrystalline silicon ingots and ribbon, and epitaxial solar cell fabrication are reviewed.
Abstract: The processing of semiconductor silicon for manufacturing low cost photovoltaic products has been a field of increasing activity over the past decade and a number of papers have been published in the technical literature. This book presents reviews on some of the key technologies developed for processing silicon for photovoltaic applications. It is complementary of Volume 5 in this series and together they provide the only collection of review in silicon photovoltaics. The volume contains papers on: the effect of introducing grain boundaries in silicon; the commercial production for multicrystalline silicon ingots and ribbon; epitaxial solar cell fabrication.
TL;DR: In this article, an electrodialysis sea water desalination system powered by photovoltaic (PV) cells is beeing developed, where the most important subject is a way to apply the varying electric power from the PV cells directry to electRodialysis with a small capacity lead battery.
TL;DR: In this paper, the authors presented an estimated performance analysis of a system that employs dichroic or spectrally selective beamsplitters (SSBS) developed by the authors.
Patent•
04 Sep 1987
TL;DR: In this paper, a solar cell (10) generates an electrical voltage with contributions from both photovoltaic and thermoelectric effects, when a high thermal gradient is impressed across a semiconductor p/n solar cell.
Abstract: A solar cell (10) generates an electrical voltage with contributions from both photovoltaic and thermoelectric effects, when a high thermal gradient is impressed across a semiconductor p/n solar cell. To achieve a substantial thermoelectric voltage contribution, the front side (12) of the solar cell (10) is heated to an elevated temperature consistent with efficient operation of the photovoltaic mechanism of the solar cell, and the back side (14) of the solar cell (10) is cooled to a lower temperature. The magnitude of the thermoelectric voltage contribution is increased by reducing the coefficient of thermal conductivity of the solar cell material, by using face electrodes (24, 26) having the proper thermoelectric potentials in contact with the solar cell material, by increasing the light intensity and thence the heat input to the front side (12) of the solar cell (10) and by cooling the back side (14) of the solar cell (10). The preferred material of construction is gallium arsenide, and the solar cell can be mounted to receive concentrated sunlight on its front side and to be cooled on its back side by enhanced thermal radiation.
Proceedings Article•
01 Jan 1987
TL;DR: In this paper, the authors report results of experimental temperature coefficient measurements obtained on a wide variety of different photovoltaic devices, many of which have not had temperature coefficient data published previously.
Abstract: It is well-known that the maximum power output of photovoltaic devices changes with temperature. Therefore, the temperature coefficients of the basic device performance parameters (open-circuit voltage, short-circuit current, fill factor, and efficiency) are important factors which must be taken into account in the design of a photovoltaic power system, where temperature changes occur throughout the day and year. This paper reports results of experimental temperature coefficient measurements obtained on a wide variety of different photovoltaic devices, many of which have not had temperature coefficient data published previously.
TL;DR: In this paper, a concentrating photovoltaic system has been built that uses Fresnel lenses of a potentially low cost design, and which employs a simple and robust method for bonding solar cells to the cooling tube.
Patent•
20 Jan 1987TL;DR: In this paper, a power regulator adjusts the operating point of one source as a function of only the sensed current conditions of the secondary source for a power system having a single maximum power point and varying loads.
Abstract: For a power system having a single maximum power point and varying loads, the present invention provides a power regulator which adjusts the operating point of one source as a function of only the sensed current conditions of the secondary source. In the preferred embodiment, a solar array is controlled by a regulator which determines whether the battery is properly charging. Upon the occurrence of an undercharging condition, the array operating point is adjusted so as to minimize undercharge current. Upon the occurrence of a charging condition, the operating point is adjusted so as to continue battery charging according to predetermined limits.
Patent•
11 Aug 1987
TL;DR: The solar cells of a photovoltaic solar cell array are protected from the effects of voltage/plasma interaction in a space environment by integral cell support ridges as mentioned in this paper.
Abstract: The solar cells of a photovoltaic solar cell array are protected from the effects of voltage/plasma interaction in a space environment The solar array includes a glass enclosure having a substrate and superstrate with integral cell support ridges The solar cells are held in place, without bonding, by the integral cell support ridges The solar array is capable of withstanding severe temperature cycling, as the solar cells can freely expand and contract independent of the substrate or superstrate In addition, a conductive grid is provided on the outer surface of the solar array to provide a zero-potential ground plane to reduce the electric field The conductive grid provides additional protection against voltage/plasma interaction should the glass enclosure develop holes or cracks, for example, by the penetration of a micrometeor
TL;DR: A review of measurements of the current vs. voltage, temperature, intensity and spectrum in photovoltaic (PV) devices is presented in this article, where the relative merits of manual vs. automated and research vs. production current-voltage and current-wavelength (spectral response) instrumentation are discussed.
Patent•
31 Aug 1987
TL;DR: In this paper, a voltage source (negative impedance) which is controlled by the output voltage and is supplied from the solar module is used instead of a regulating resistor, which consumes energy.
Abstract: This regulator increases the output power of photovoltaic modules exactly to that output voltage (battery charging voltage) which is just required even when the solar radiation is weak, and at the same time keeps the solar module very close to the characteristic point of maximum energy yield (Maximum Power Tracking, MPT). Inflating of the number of solar cells is superfluous, that is to say 20-30% of the investment costs are saved. Use of a single, very simple circuit results in: MPT plus charging regulator with overload protection and deep-discharge protection - without any reductions in efficiency, which can be 100% in the case of full solar radiation and approximately 98% in the case of weak solar radiation. The trick is to reverse the principle of the voltage-reducing in-phase regulator: a voltage source (negative impedance) which is controlled by the output voltage and is supplied from the solar module is used instead of a regulating resistor, which consumes energy. The voltage from said solar module, which is controlled automatically, is added to the module voltage. The circuit is generally suitable for any variable DC voltage source, for achieving constant (or controlled) output voltages at high efficiency and at low cost.
Patent•
13 Mar 1987TL;DR: In this paper, a power converting apparatus comprising an intermediate DC power which rectifies AC from a commercial power to output DC, a solar array connected in parallel to the intermediate DC, an inverter which converts DC inputted respectively from the intermediate dc power and the solar array into AC having the variable frequency and the variable voltage, then supply its AC output to a load, and circuit networks for power regeneration which regenerates a surplus power of the solar arrays into the commercial power, when the generated voltage of solar array exceeds the prescribed voltage.
Abstract: A power converting apparatus comprising intermediate DC power which rectifies AC from a commercial power to output DC, a solar array connected in parallel to the intermediate DC power, an inverter which converts DC inputted respectively from the intermediate DC power and the solar array into AC having the variable frequency and the variable voltage, then supply its AC output to a load, and circuit networks for power regeneration which regenerates a surplus power of the solar array into the commercial power, when the generated voltage of the solar array exceeds the prescribed voltage.
TL;DR: In this paper, the authors present a generic mathematical framework which is used for the analysis of the shadow effect of large-scale solar power systems (photovoltaic or thermal) of different kinds in increasing and the shading effect of neighboring collectors becomes critical for the optimal design of such systems.
TL;DR: In this paper, the application of a new hydroelectric generator air-gap measurement system is presented, which is a continuous on-line system using optical triangulation, fiber-optic, and a microprocessor-based monitor.
Abstract: This paperpresents theapplication ofa new hydroelectric generator air-gap measurementsystem. Itisa continuous on-line systemusing optical triangulation, fiber- optics, a microprocessor-based monitor, specially developed
Patent•
18 Dec 1987
TL;DR: In this paper, the open circuit voltage of the photovoltaic array (41) is sensed by inhibiting the operation of the switching power converter for short sampling periods at regular intervals.
Abstract: Electrical power transfer apparatus (40) for controlling the supply of electrical power from an array of photovoltaic cells (41) to an electrical load (46) by means of a switching power converter (45). The switching power converter (45) is controlled by a regulator (58) to maintain the output voltage from the photovoltaic array (41) at a fixed fraction of the open circuit voltage of the photovoltaic array (41), the fixed fraction suitably being between 0.75 and 0.8, whereby the power transfer from the photovoltaic array (41) is maximised. The open circuit voltage of the photovoltaic array (41) is sensed by inhibiting the operation of the switching power converter for short sampling periods at regular intervals, and allowing a capacitor (52) to charge to the voltage of the open-circuited photovoltaic array (41) during the sampling periods.
01 Jan 1987
Patent•
18 Dec 1987
TL;DR: In this article, the open circuit voltage of the photovoltaic array (41) is sensed by inhibiting the operation of the switching power converter for short sampling periods at regular intervals.
Abstract: Electrical power transfer apparatus (40) for controlling the supply of electrical power fram an array of photovoltaic cells (41) to an electrical load (46) by means of a switching power converter (45). The switching power converter (45) is controlled by a regulator (58) to maintain the output voltage from the photovoltaic array (41) at a fixed fraction of the open circuit voltage of the photovoltaic array (41), the fixed fraction suitably being between 0.75 and 0.8, whereby the power transfer from the photovoltaic array (41) is maximized. The open circuit voltage of the photovoltaic array (41) is sensed by inhibiting the operation of the switching power converter for short sampling periods at regular intervals, and allowing a capacitor (52) to charge to the voltage of the open-circuited photovoltaic array (41) during the sampling periods.