SEARCH · Engineering Papers

Results for “Solar PV”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4

All sources NASA NTRS DOE OSTI

NASA NTRS2007

Preliminary Low Temperature Electron Irradiation of Triple Junction Solar Cells

For many years extending solar power missions far from the sun has been a challenge not only due to the rapid falloff in solar intensity (intensity varies as inverse square of solar distance) but also because some of the solar cells in an array may exhibit a LILT (low intensity low temperature) degradation that reduces array performance. Recent LILT tests performed on commercial triple junction solar cells have shown that high performance can be obtained at solar distances as great as approx. 5 AU1. As a result, their use for missions going far from the sun has become very attractive. One additional question that remains is whether the radiation damage experienced by solar cells under low temperature conditions will be more severe than when measured during room temperature radiation tests where thermal annealing may take place. This is especially pertinent to missions such as the New Frontiers mission Juno, which will experience cell irradiation from the trapped electron environment at Jupiter. Recent testing2 has shown that low temperature proton irradiation (10 MeV) produces cell degradation results similar to room temperature irradiations and that thermal annealing does not play a factor. Although it is suggestive to propose the same would be observed for low temperature electron irradiations, this has not been verified. JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature. A fluence of 1E15 1MeV electrons was selected as representative of a moderately high dose that might be expected for a solar powered mission. Fluences much greater than this would require large increases in array area and mass, compromising the ability of PV to compete with non-solar alternatives.

Stella, Paul M.↗

NASA NTRS2015

Space Environment Testing of Photovoltaic Array Systems at NASA's Marshall Space Flight Center

CubeSats, Communication Satellites, and Outer Planet Science Satellites all share one thing in common: Mission success depends on maintaining power in the harsh space environment. For a vast majority of satellites, spacecraft power is sourced by a photovoltaic (PV) array system. Built around PV cells, the array systems also include wiring, substrates, connectors, and protection diodes. Each of these components must function properly throughout the mission in order for power production to remain at nominal levels. Failure of even one component can lead to a crippling loss of power. To help ensure PV array systems do not suffer failures on-orbit due to the space environment, NASA's Marshall Space Flight Center (MSFC) has developed a wide ranging test and evaluation capability. Key elements of this capability include: Testing: a. Ultraviolet (UV) Exposure b. Charged Particle Radiation (Electron and Proton) c. Thermal Cycling d. Plasma and Beam Environments Evaluation: a. Electrostatic Discharge (ESD) Screening b. Optical Inspection and easurement c. PV Power Output including Large Area Pulsed Solar Simulator (LAPSS) measurements This paper will describe the elements of the space environment which particularly impact PV array systems. MSFC test capabilities will be described to show how the relevant space environments can be applied to PV array systems in the laboratory. A discussion of MSFC evaluation capabilities will also be provided. The sample evaluation capabilities offer test engineers a means to quantify the effects of the space environment on their PV array system or component. Finally, examples will be shown of the effects of the space environment on actual PV array materials tested at MSFC.

Schneider, Todd A.↗

NASA NTRS1986

Crystalline-silicon photovoltaics summary module design and reliability

The evolution of the design and reliability of solar modules was described. Design requirements involved 14 different considerations, including residential building and material electrical codes, wind-loading, hail impact, operating temperature levels, module flammability, and interfaces for both the array structure and the operation of the system. Reliability research involved in diverse investigations including glass-fracture strength, soiling levels, electrochemical corrosion, and bypass-diode qualification tests. Based on these internationally recognized studies, performance assessments, and failure analyses, the Flat-plate Solar Array Project in its 11-year duration served to nuture the development of 45 different solar module designs from 15 PV manufacturers.

Ross, R. G., Jr.↗

NASA NTRS1997

Preliminary Findings of the Photovoltaic Cell Calibration Experiment on Pathfinder Flight 95-3

The objective of the photovoltaic (PV) cell calibration experiment for Pathfinder was to develop an experiment compatible with an ultralight UAV to predict the performance of PV cells at AM0, the solar spectrum in space, using the Langley plot technique. The Langley plot is a valuable technique for this purpose and requires accurate measurements of air mass (pressure), cell temperature, solar irradiance, and current-voltage(IV) characteristics with the cells directed normal to the direct ray of the sun. Pathfinder's mission objective (95-3) of 65,000 ft. maximum altitude, is ideal for performing the Langley plot measurements. Miniaturization of electronic data acquisition equipment enabled the design and construction of an accurate and light weight measurement system that meets Pathfinder's low payload weight requirements.

Vargas-Aburto, Carlos↗

NASA NTRS2005

Photovoltaic Engineering

The Ohio Aerospace Institute through David Scheiman and Phillip Jenkins provided the Photovoltaics Branch at the NASA Glenn Research Center (GRC) with expertise in photovoltaic (PV) research, flight experiments and solar cell calibration. NASA GRC maintains the only world-class solar cell calibration and measurement facility within NASA. GRC also has a leadership role within the solar cell calibration community, and is leading the effort to develop ISO standards for solar cell calibration. OAI scientists working under this grant provided much of the expertise and leadership in this area.

Source record↗

NASA NTRS2017

Energy Exchange NASA Opening Plenary

Rick Marrs, Deputy Assistant Administrator Office of Strategic Infrastructure NASA Headquarters will be speaking during the 2017 Energy Exchange opening plenary. His presentation showcases the NASA mission, sustainability at NASA, NASA's strategic Sustainability Performance Plan, Existing PV Partnerships, and NASA funded Solar Initiatives at KSC.

Marrs, Rick↗

NASA NTRS2000

SAVANT: Solar Array Verification and Analysis Tool Demonstrated

The photovoltaics (PV) industry is now being held to strict specifications, such as end-oflife power requirements, that force them to overengineer their products to avoid contractual penalties. Such overengineering has been the only reliable way to meet such specifications. Unfortunately, it also results in a more costly process than is probably necessary. In our conversations with the PV industry, the issue of cost has been raised again and again. Consequently, the Photovoltaics and Space Environment Effects branch at the NASA Glenn Research Center at Lewis Field has been developing a software tool to address this problem. SAVANT, Glenn's tool for solar array verification and analysis is in the technology demonstration phase. Ongoing work has proven that more efficient and less costly PV designs should be possible by using SAVANT to predict the on-orbit life-cycle performance. The ultimate goal of the SAVANT project is to provide a user-friendly computer tool to predict PV on-orbit life-cycle performance. This should greatly simplify the tasks of scaling and designing the PV power component of any given flight or mission. By being able to predict how a particular PV article will perform, designers will be able to balance mission power requirements (both beginning-of-life and end-of-life) with survivability concerns such as power degradation due to radiation and/or contamination. Recent comparisons with actual flight data from the Photovoltaic Array Space Power Plus Diagnostics (PASP Plus) mission validate this approach.

Chock, Ricaurte↗

NASA NTRS2002

Battery Reinitialization of the Photovoltaic Module of the International Space Station

The photovoltaic (PV) module on the International Space Station (ISS) has been operating since November 2000 and supporting electric power demands of the ISS and its crew of three. The PV module contains photovoltaic arrays that convert solar energy to electrical power and an integrated equipment assembly (IEA) that houses electrical hardware and batteries for electric power regulation and storage. Each PV module contains two independent power channels for fault tolerance. Each power channel contains three batteries in parallel to meet its performance requirements and for fault tolerance. Each battery consists of 76 Ni-Hydrogen (Ni-H2) cells in series. These 76 cells are contained in two orbital replaceable units (ORU) that are connected in series. On-orbit data are monitored and trended to ensure that all hardware is operating normally. Review of on-orbit data showed that while five batteries are operating very well, one is showing signs of mismatched ORUs. The cell pressure in the two ORUs differs by an amount that exceeds the recommended range. The reason for this abnormal behavior may be that the two ORUs have different use history. An assessment was performed and it was determined that capacity of this battery would be limited by the lower pressure ORU. Steps are being taken to reduce this pressure differential before battery capacity drops to the point of affecting its ability to meet performance requirements. As a first step, a battery reinitialization procedure was developed to reduce this pressure differential. The procedure was successfully carried out on-orbit and the pressure differential was reduced to the recommended range. This paper describes the battery performance and the consequences of mismatched ORUs that make a battery. The paper also describes the reinitialization procedure, how it was performed on orbit, and battery performance after the reinitialization. On-orbit data monitoring and trending is an ongoing activity and it will continue as ISS assembly progresses.

Hajela, Gyan↗

NASA NTRS1993

Ion measurements during Pioneer Venus reentry: Implications for solar cycle variation of ion composition and dynamics

During the final, low solar activity phase of the Pioneer Venus (PV) mission, the Orbiter Ion Mass Spectrometer (OIMS) measurements found all ion species, in the midnight-dusk sector, reduced in concentration relative to that observed at solar maximum. Molecular ion species comprised a greater part of the total ion concentration as O(+) and H(+) had the greatest depletions. The nightside ionospheric states were strikingly similar to the isolated solar maximum 'disappearing' ionospheres. Both are very dynamic states characterized by a rapidly drifting plasma and 30-100 eV superthermal O(+) ions.

Grebowsky, J. M.↗

NASA NTRS1982

Design description of the Tangaye Village photovoltaic power system

The engineering design of a stand alone photovoltaic (PV) powered grain mill and water pump for the village of Tangaye, Upper Volta is described. The socioeconomic effects of reducing the time required by women in rural areas for drawing water and grinding grain were studied. The suitability of photovoltaic technology for use in rural areas by people of limited technical training was demonstrated. The PV system consists of a 1.8-kW (peak) solar cell array, 540 ampere hours of battery storage, instrumentation, automatic controls, and a data collection and storage system. The PV system is situated near an improved village well and supplies d.c. power to a grain mill and a water pump. The array is located in a fenced area and the mill, battery, instruments, controls, and data system are in a mill building. A water storage tank is located near the well. The system employs automatic controls which provide battery charge regulation and system over and under voltage protection. This report includes descriptions of the engineering design of the system and of the load that it serves; a discussion of PV array and battery sizing methodology; descriptions of the mechanical and electrical designs including the array, battery, controls, and instrumentation; and a discussion of the safety features. The system became operational on March 1, 1979.

Martz, J. E.↗

NASA NTRS2014

On-Orbit Measurement of Next Generation Space Solar Cell Technology on the International Space Station

On-orbit measurements of new photovoltaic (PV) technologies for space power are an essential step in the development and qualification of advanced solar cells. NASA Glenn Research Center will fly and measure several solar cells attached to NASA Goddards Robotic Refueling Mission (RRM), expected to be launched in 2014. Industry and government partners have provided advanced PV devices for evaluation of performance and environmental durability. The experiment is completely self-contained, providing its own power and internal data storage. Several new cell technologies including Inverted Metamorphic Multi-junction and four-junction cells will be tested.

robotic refueling mission↗

NASA NTRS1993

Evidence for day-to-night ion transport at low solar activity in the Venus pre-dawn ionosphere

Periapsis of the Pioneer Venus (PV) spacecraft dropped below 180 km on August 28, 1992 near midnight, and 42 orbits of low altitude data at moderately low solar activity in the pre-dawn sector were obtained before contact was lost to the spacecraft in October, 1992. Through a combination of analysis of data from the PV orbiter ion mass spectrometer (OIMS) and modeling, we consider here what can be learned about the relative importance of plasma transport from the dayside and electron precipitation in maintaining the nightside ionosphere during the re-entry period. In particular, we examine here the atomic ion density profiles. We compute the average peak density of O(+) as a function of solar zenith angle and determine what fluxes of atomic ions or precipitating electrons would be necessary to produce those values. We then compare model calculations of the ion densities to those observed during the re-entry period. We find that the low solar activity nightside ionosphere shows evidence of significant day-to-night plasma transport.

Brannon, J. F.↗

NASA NTRS1986

Sensitivity analysis for solar plates

Economic evaluation methods and analyses of emerging photovoltaic (PV) technology since 1976 was prepared. This type of analysis was applied to the silicon research portion of the PV Program in order to determine the importance of this research effort in relationship to the successful development of commercial PV systems. All four generic types of PV that use silicon were addressed: crystal ingots grown either by the Czochralski method or an ingot casting method; ribbons pulled directly from molten silicon; an amorphous silicon thin film; and use of high concentration lenses. Three technologies were analyzed: the Union Carbide fluidized bed reactor process, the Hemlock process, and the Union Carbide Komatsu process. The major components of each process were assessed in terms of the costs of capital equipment, labor, materials, and utilities. These assessments were encoded as the probabilities assigned by experts for achieving various cost values or production rates.

Aster, R. W.↗

NASA NTRS1986

Flat-plate solar array project. Volume 7: Module encapsulation

The objective of the Encapsulation Task was to develop, demonstrate, and qualify photovoltaic (PV) module encapsulation systems that would provide 20 year (later decreased to 30 year) life expectancies in terrestrial environments, and which would be compatible with the cost and performance goals of the Flat-Plate Solar Array (FSA) Project. The scope of the Encapsulation Task included the identification, development, and evaluation of material systems and configurations required to support and protect the optically and electrically active solar cell circuit components in the PV module operating environment. Encapsulation material technologies summarized include the development of low cost ultraviolet protection techniques, stable low cost pottants, soiling resistant coatings, electrical isolation criteria, processes for optimum interface bonding, and analytical and experimental tools for evaluating the long term durability and structural adequacy of encapsulated modules. Field testing, accelerated stress testing, and design studies have demonstrated that encapsulation materials, processes, and configurations are available that meet the FSA cost and performance goals.

Cuddihy, E.↗

NASA NTRS2000

Power System Options Evaluated for the Radiation and Technology Demonstration Mission

The Radiation and Technology Demonstration (RTD) Mission is under joint study by three NASA Centers: the NASA Johnson Space Center, the NASA Goddard Space Flight Center, and the NASA Glenn Research Center at Lewis Field. This Earth-orbiting mission, which may launch on a space shuttle in the first half of the next decade, has the primary objective of demonstrating high-power electric thruster technologies. Secondary objectives include better characterization of Earth's Van Allen trapped-radiation belts, measurement of the effectiveness of the radiation shielding for human protection, measurement of radiation effects on advanced solar cells, and demonstration of radiation-tolerant microelectronics. During the mission, which may continue up to 1 year, the 2000-kg RTD spacecraft will first spiral outward from the shuttle-deployed, medium-inclination, low Earth orbit. By the phased operation of a 10-kW Hall thruster and a 10-kW Variable Specific Impulse Magneto-Plasma Rocket, the RTD spacecraft will reach a low-inclination Earth orbit with a radius greater than five Earth radii. This will be followed by an inward spiraling orbit phase when the spacecraft deploys 8 to 12 microsatellites to map the Van Allen belts. The mission will conclude in low Earth orbit with the possible retrieval of the spacecraft by the space shuttle. A conceptual RTD spacecraft design showing two photovoltaic (PV) array wings, the Hall thruster with propellant tanks, and stowed microsatellites is presented. Early power system studies assessed five different PV array design options coupled with a 120-Vdc power management and distribution system (PMAD) and secondary lithium battery energy storage. Array options include (1) state-of-the-art 10-percent efficient three-junction amorphous SiGe thin-film cells on thin polymer panels deployed with an inflatable (or articulated) truss, (2) SCARLET array panels, (3) commercial state-of-the-art, planar PV array rigid panels with 25-percent efficient, three-junction GaInP2/GaAs/Ge solar cells, (4) rigid panels with 25-percent efficient, three-junction GaInP2/GaAs/Ge solar cells, in a 2 -concentrator trough configuration, and (5) thin polymer panels with 25-percent efficient, three-junction GaInP2/GaAs/Ge solar cells deployed with an inflatable (or articulated) truss. To assess the relative merits of these PV array design options, the study group developed a dedicated Fortran code to predict power system performance and estimate system mass. This code also modeled Earth orbital environments important for accurately predicting PV array performance. The most important environmental effect, solar cell radiation degradation, was calculated from electron-proton fluence input from the industry standard AE8/AP8 trapped radiation models and the concept of damage equivalence. Power systems were sized to provide 10 kW of thruster power and approximately 1 kW of spacecraft power at end of life. Of the five PV array design options, the option 1 (thin-film cells) power system was the most massive 590 kg, whereas the option 4 (trough concentrator) power system was the lightest 260 kg. Arguably, the lowest cost would come from the option 3 (commercial array panels) power system with an acceptable, albeit greater, system mass of 320 kg. Predicted power system performance during the spiral-out mission phase is shown the preceding graph for the option 5 (flexible-panel) array. From the results, the radiation-induced power loss over time is evident as the spacecraft slowly spirals outward through the trapped proton belt. The importance of the spiral trip time is also evident in the two curves representing 74-day and 182-day spiral-out periods. The longer spiral time introduces a beginning-of-life power oversizing penalty greater than 1 kW. Future studies will analyze power system performance and mass with a 50-Vdc power management and distribution architecture favorable to the VASIMR thruster and longer missions.

Kerslake, Thomas W.↗

NASA NTRS2003

The Implementation of Advanced Solar Array Technology in Future NASA Missions

Advanced solar array technology is expected to be critical in achieving the mission goals on many future NASA space flight programs. Current PV cell development programs offer significant potential and performance improvements. However, in order to achieve the performance improvements promised by these devices, new solar array structures must be designed and developed to accommodate these new PV cell technologies. This paper will address the use of advanced solar array technology in future NASA space missions and specifically look at how newer solar cell technologies impact solar array designs and overall power system performance.

Piszczor, Michael F.↗

NASA NTRS2007

Recovery of Electron/Proton Radiation-Induced Defects in n+p AlInGaP Solar Cell by Minority-Carrier Injection Annealing

A high efficient In0.48Ga0.52P/In0.01Ga0.99As/Ge triple junction solar cell has been developed for application in space and terrestrial concentrator PV system [1-3]. Recently, a high conversion efficiency of 31.5% (AM1.5G) has been obtained in InGaP/(In)GaAs/Ge triple junction solar cell, and as a new top cell material of triple junction cells, (Al)InGaP [1] has been proposed to improve the open-circuit voltage (Voc) because it shows a higher Voc of 1.5V while maintaining the same short-circuit current (ISC) as a conventional InGaP top cell under AM1.5G conditions as seen in figure 1 (a). Moreover, the spectral response of 1.96eV AlInGaP cell with a thickness of 2.5..m shows a higher response in the long wavelength region, compared with that of 1.87eV InGaP cell with 0.6..m thickness, as shown in figure 1 (b). Its development will realize next generation multijunction (MJ) solar cells such as a lattice mismatched AlInGaP/InGaAs/Ge 3-junction and lattice matched AlInGaP/GaAs/InGaAsN/Ge 4-junction solar cells. Figure 2 shows the super high-efficiency MJ solar cell structures and wide band spectral response by MJ solar cells under AM1.5G conditions. For realizing high efficient MJ space solar cells, the higher radiation-resistance under the electron or proton irradiation is required. The irradiation studies for a conventional top cell InGaP have been widely done [4-6], but little irradiation work has been performed on AlInGaP solar cells. Recently, we made the first reports of 1 MeV electron or 30 keV proton irradiation effects on AlInGaP solar cells, and evaluated the defects generated by the irradiation [7,8]. The present study describes the recovery of 1 MeV electron / 30 keV proton irradiation-induced defects in n+p- AlInGaP solar cells by minority-carrier injection enhanced annealing or isochronal annealing. The origins of irradiation-induced defects observed by deep level transient spectroscopy (DLTS) measurements are discussed.

Lee, H. S.↗

NASA NTRS1989

Launch packaging options for the photovoltaic power module cargo element

The National Aeronautics and Space Administration recently embarked on the Space Station Freedom program, which will utilize the Shuttle Orbiter for transportation to orbit. This task will be accomplished with a number of flights over several years. Each flight is unique in terms of the hardware that is manifested and the method by which it is integrated to form viable cargo elements. Work Package 4 is responsible for the electric power system for Space Station Freedom, and was delegated the authority to develop a photovoltaic (PV) power module cargo element. The PV power module consists of several unique assemblies. The first of these is the combined solar array/beta gimbal assembly. The remaining assemblies form the single combined integrated equipment assembly for each PV power module. These three combined assemblies are packaged into a launch cradle to form the PV power module cargo element, which is placed in the cargo bay of the Shuttle Orbiter for transportation to orbit. Various constraints determine the packaging options for the three PV power module combined assemblies. The size and shape of the combined assemblies in relation to the Shuttle Orbiter cargo bay dimensions and other manifested hardware are ultimately a factor in determining the acceptable packaging schemes for the PV power module cargo element. Several packaging options for the PV power module cargo element are presented. These options are discussed in terms of their impact on the overall flight hardware manifest as determined by the various constraints.

Hoberecht, Mark A.↗