Showing papers on "Photovoltaic system published in 1970"

System for detecting and utilizing the maximum available power from solar cells

Abstract: In a power solar cell array consisting of many solar cells connected to deliver useful electrical power, there is imbedded a smaller reference solar array consisting of solar cells connected in series with a Zener diode and load resistor so devised that the voltage that appears across the load resistor is equal to or a constant fraction of the voltage at which the power array, operating at the same temperature and solar exposure as the reference array, delivers maximum electrical power. The voltage difference between the large solar array or the given fraction thereof and the reference solar array is used directly as means to constrain the large array to operate at the voltage of maximum power, typically any excess power being used to charge a storage battery.

Flexible solar cell modular assembly

Abstract: A module for a solar cell panel with silicon photovoltaic cells fused between two sheets of FEP Teflon. The plastic is mounted on an aluminum frame with two side members adapted to interlock with similar modules. The side frame members also act as current carrying bass members.

Optimum performance spacecraft solar cell system

Abstract: A spacecraft solar cell system including a switching circuit which comprises relay operated switches for changing a plurality of solar cells from a first series-parallel interconnection to a second series-parallel interconnection is disclosed. The relays are actuated by a command device which may be a telemetry receiver. A protection circuit comprising a photodiode is connected between the command device and the relays to ensure appropriate solar cell orientation when switching occurs. This prevents arcing across the relay switches.

Solar energy powered heliotrope

Abstract: This invention relates to a solar energy powered heliotrope which functions in a passive, stored energy manner to orient a solar array towards the sun. A bimetallic motor element is activated by solar energy to generate a work output. A constant torque spring assembly coupled to the motor element stores useful energy as a function of the work output. A bimetallic sensing element detects misorientation between the solar array and the sun. An escapement mechanism is actuated by the sensing element whenever misorientation between the solar array and the sun is detected; the escapement mechanism automatically and incrementally releases the stored energy to rotate the solar array in discrete increments until it is oriented towards the sun.

Low-Energy Proton Damage to Silicon Solar Cells

Abstract: The effect of low-energy (<2 MeV) proton irradiation upon the junction properties of silicon solar cells has been measured. These measurements are used to explain the large power loss observed on the ATS-1 and Intelsat II-4 satellites.

High voltage solar arrays with integral power conditioning

Abstract: High voltage solar array with integral power conditioning, discussing weight factors, panel design and layout, mechanization, performance prediction, etc

Power Without Pollution

Abstract: A concept for a satellite solar power station is described to meet future large scale electrical power requirements without burdening the environment or leading to natural resource exhaustion. Considerations are given to solar energy conversion, microwave generation and transmission, and conversion of microwave energy to electrical power on earth. The system considerations and the development tasks for a large satellite solar power station are reviewed and the potential technilogical needs are identified.

Method and apparatus for calibrating a solar array

Abstract: A method and apparatus for calibrating a solar array to predict its characteristic volt-ampere or I-V curve in outer space by periodically illuminating the array in rapid succession with a flashlamp whose radiation closely simulates natural solar radiation in outer space, and measuring the array current at short circuit, open circuit, and selected array voltage levels. The output of a standard cell which is illuminated concurrently with the solar array by each flash is recorded to permit correction for any variation from flash-to-flash.

Oriented flexible rolled-up solar array

Abstract: Space power systems in use at the present time require up to 407o of the in-orbit spacecraft weight allocation as well as a sizable launch volume allocation for high power systems. The Oriented Flexible Rolled-Up Solar Array program (FRUSA) was initiated to reduce both the weight and launch volume requirements of the power subsystem and to fulfill the need for reliable, cost effective large power systems. The FRUSA'program has increased the watts per pound figure of merit by a minimum of 2.5, reduced the launch volume to an acceptable level, and provided the technology to cost effectively expand the use of photovoltaic systems to the range 100 kw and beyond. Introduction Sunlight is the most cost-effective source of spacecraft electrical power during flight. However, as spacecraft increase in size, the amount of electrical power that can be supplied by surface-mounted solar cells does not increase at the same rate as the payload volume. To keep power and size in step, rolled-up arrays deployed in orbit have been developed. Hughes verified the feasibility of the flexible array concept with a 500-w model and design of a deployment and orientation system. FRUSA is a complete 1500-w power system that can be extended or retracted in orbit by command. Representing an average 30070 increase in w-lb ratio over current spacecraft power systems, FRUSA, designed for low Earth and synchronous orbits, is compatible with electrically propelled Presented as Paper 70-738 at the AIAA 3rd Communications Satellite Systems Conference, Los Angeles, Calif.,April 6-8, 1970. The author acknowledges the contribution to this paper made by A. Wittman, Senior Project Engineer, Structural Mechanics Department, and R.B. Clark, Manager of the Liquid Slip Ring Project, both of Hughes Aircraft Company. ^Associate Program Manager, FRUSA Program. (Now in development under contract F33615-68-C-1676 to Air Force Aero Propulsion Laboratory, Wright-Patterson AFB. 409 Purchased from American Institute of Aeronautics and Astronautics

Flexible Rolled-Up Solar Array.

Abstract: : The main activities on the Flexible Rolled-Up Solar Array (FRUSA) program during the ninth quarterly reporting period consisted of assembly of the development/qualification model of the orientation mechanism, solar array, drum mechanism, control electronics unit (CEU), and solar cell electronics unit (SCEU). Cells, simulated blanks, and busses were bonded to the two qualification model panels. The panels were connected to the drum mechanism, which had been assembled without the interface wiring and water table deployment/retraction tests on the complete assembly successfully conducted. Functional acceptance testing of the CEU and the SCEU have been initiated. The instrumentation conditioning unit (ICU) is still awaiting the two hi-reliability capacitors before acceptance tests can be initiated. Fabrication of detailed parts for the power conditioning unit (PCU) and battery/charge controller are nearing completion, and detailed parts drawings and the schematic have been released for the load bank assembly. An updated FRUSA/Agena wiring diagram, Space Experiment Plan, and Flight Model Design and Test Specification have been completed and submitted to Wright-Patterson Air Force Base. (Author)

Limits of grid extension in the Lao PDR: A financial perspective

Abstract: This paper articulates a financial model for estimating the limits of grid extensionin the Lao PDR versus three decentralised renewable energy (DRE) options: micro-hydropower,pico-hydropower and solar photovoltaic. The model is based on a like-for-like comparison of thedifferent DRE options against grid extension, such that each option supplies the same amount ofelectricity (in kWh) over the project timeframe. The amount of electricity supplied is estimatedbased on the forecast electricity demand of a typical rural Lao household. Therefore, if a householdconsumes 7 kWh per day, then the micro-hydro, pico-hydro, solar PV and grid extension systems areall sized in the model to supply 7 kWh per day. This is in contrast to more conventional approaches,where grid extension is compared to DRE systems of typically lower capacities (e.g. grid extensioncompared against 50 W solar home systems). The limits of grid extension are expressed in termsof a breakeven distance, which is the maximum distance from a village at which grid extension isthe more cost-effective option. Beyond this breakeven distance, DRE technologies can be installedat a lower cost, while providing the same amount of electricity to the end-user.

A regulated solar-array model-a tool for power systems analysis

Abstract: A digitally regulated solar-array represents a new concept in high-voltage power supply regulation, A mathematical model of the key elements of such a regulator is presented. It can be used in the performance evaluation of the interface between such a power source and a typical load. A range of load conditions and source states can be simulated. The model permits easy incorporation of source performance changes e.g. changes to solar-cell volt-ampere characterisitics due to temperature or due to radiation degradation.

Performance of a Solar Heating System with Photovoltaic Thermal Hybrid Collectors and Heat Pump

Abstract: The energy consumption in buildings accounts for a large part of the World’s CO2 emissions. Much energy is used for appliances, domestic hot water preparation and space heating. In solar heating systems, heat is captured by solar collectors when the sun is shining and used for heating purposes. When the solar collectors are unable to supply the heat demand an auxiliary heat source is used. Heat pumps can generate this heat. Liquid/water heat pumps have better performance than air/water heat pumps in cold climates but requires installation of a tubing system for the cold side of the heat pump. The tubes are typically placed in the ground, requires a significant land area and increase the installation cost. A new system design of a solar heating system with two storage tanks and a liquid/water heat pump is presented. The system consists of PVT collectors that generate both heat and electricity. Heat from the collectors is transferred to a domestic hot water storage tank or to a cold storage tank, which is used as the source for the heat pump. When the heat pump charges the warm storage tank, heat is extracted from the cold storage tank, which then can be reheated by the PVT collectors. In this system, it is possible to have the high performance of the liquid/water heat pump but without the need to install tubes in the ground. The performance of the system with automated energy discharge over several months is evaluated.

High-voltage solar array for ion engines

Abstract: High voltage solar arrays for ion engines, discussing spacecraft propulsion, electric generation, insulation integrity, cell degradation and current leakage

La formación en energía solar fotovoltáica en la Universidad Politécnica de Valencia.

Abstract: The installation of a solar photovoltaic station at the Universidad Politecnica de Valencia (UPV) in 1999 was an important step in bringing the UPV closer to the increasingly important alternative energy sources such as solar and wind. The solar photovoltaic station can produce 17,5 kWp and contains 234 solar panels, six monophase inverters supplying power to the electrical grid, a data acquisition system and a weather station.

Radiation effects in silicon solar cells

Abstract: Silicon solar cells have been utilized as the principal source of electrical energy for space satellites during the past decade. Despite the reliability of these photovoltaic devices, degradation of their power output by charged particle radiation in the earth's geomagnetic field has continued to be the primary problem for their use on flights of long-duration. A study of radiation damage induced by 1 MeV electrons in a variety of current silicon solar cell types has been conducted as a function of dopant impurity and resistivity of the base region. A companion study of radiation damage induced by nominal 0.2 MeV protons was performed in solar cells with coverslips having small cell areas exposed alongside the coverslip. The photovoltaic current-voltage characteristics were measured under a solar simulator emitting 140mW/cm2 at air mass zero. Irradiations were performed at room temperature to fluences of 1 × 1015 e/cm2 and 1 × 1015 p/cm2. The efficiency of 10 ohm-cm cells after large fluences was...

Maximum power transfer by conductance comparison

Abstract: Most scientific satellites to date have utilized solar cells as the main power source for the spacecraft payload. Two basic methods have been utilized for operating a solar cell array at or near the maximum power point of its I-V characteristics. These two methods may be categorized as either an open loop system or a closed loop system. An open loop system makes use of design parameters of the solar array whereas a closed loop system constantly monitors some system parameter in order to determine maximum power point operation.

Development of an integrated lightweight flexible silicon solar cell array Final report

Abstract: Methods and analytical techniques for fabricating integrated lightweight flexible silicon solar array blanket

SPOT-4 Solar Array Deployment - Tests/analysesCorrelation

Abstract: To validate the complex in-flight deployment of the new SPOT solar array, a mix of accurate simulations and ground tests was required. We describe in this paper the activities performed at MATRA MARCONI Space to predict the kinematics and dynamics of the deployment with special emphasis on the ground tests which were conducted to validate our prediction models. The successful in-flight deployment of a solar array of the same design has confirmed the validity of our analyses.

High voltage solar array electrical configuration study Final report

Abstract: Mathematical models for increasing reliability and reducing weight of high voltage solar-cell power systems for spacecraft

A Portable Photovoltaic Powerplant for Emergency Electrical Power Supply in Disaster Affected Areas

Abstract: We propose a novel portable photo voltaic electric generator capable of tracking sunlight in all directions essential for disaster areas. Such occurrence often results in disruptions of public services especially power grids. The system prototype consists of a 10W solar panels capable of two axes motion of 120° horizontal and 360° azimuth driven by ATMega8535 micro controller. Two-axis movement is based on two types of sensors capable of 360° directional movements based on the HMC5883 compass sensor. This compass sensor panel is also configured to always directs towards the sun so that if the direction of the base plate was changed, it will automatically direct the panel to the direction of the sun; while 120° vertical movement based on three pieces of LDR (Light Dependent Resistor) as sun sensors. Thus the amount of light received and hence the power output are maximized.