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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.

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At least 181 records · Page 10

The potential of np GaAs solar cells for high efficiency concentrator applications

This communication considers the design of the front grid contact of np GaAs solar cells for high efficiency concentrator applications. This design involves shadowing, contact resistance, and active layer sheet resistance losses, and at high concentrations, the power loss due to voltage drop on the resistance of the grid fingers should be considered. Analysis of the performance can be calculated as a function of junction depth and surface recombination velocity. The junction depth can be optimized by considering its effect on the collection efficiency of the dark current-voltage characteristics or the open circuit voltage, and on the series resistance loss or the fill factor for material parameters. The choice of the material parameters, calculation of the short circuit current, the selection of the n layer thickness, and the cell maximum power and efficiency are discussed. It is concluded that optimized multi-grid structures should allow the use of 10 by 10 sq cm cells with good efficiencies at high concentration ratios, and efficiencies of 22 to 25% should be obtainable from large area cells at concentrations of 40 AM1.

Flat, A.↗

Solutions Network Formulation Report. NASA's Potential Contributions for Using Solar Ultraviolet Radiation in Conjunction with Photocatalysis for Urban Air Pollution Mitigation and Increasing Air Quality

This Candidate Solution is based on using NASA Earth science research on atmospheric ozone and aerosols data as a means to predict and evaluate the effectiveness of photocatalytically created surfaces (building materials like glass, tile and cement) for air pollution mitigation purposes. When these surfaces are exposed to near UV light, organic molecules, like air pollutants and smog precursors, will degrade into environmentally friendly compounds. U.S. EPA (Environmental Protection Agency) is responsible for forecasting daily air quality by using the Air Quality Index (AQI) that is provided by AIRNow. EPA is partnered with AIRNow and is responsible for calculating the AQI for five major air pollutants that are regulated by the Clean Air Act. In this Solution, UV irradiance data acquired from the satellite mission Aura and the OMI Surface UV algorithm will be used to help understand both the efficacy and efficiency of the photocatalytic decomposition process these surfaces facilitate, and their ability to reduce air pollutants. Prediction models that estimate photocatalytic function do not exist. NASA UV irradiance data will enable this capability, so that air quality agencies that are run by state and local officials can develop and implement programs that utilize photocatalysis for urban air pollution control and, enable them to make effective decisions about air pollution protection programs.

Underwood, Lauren↗

Lunar Solar Origins Exploration (LunaSOX)

The Moon offers a unique vantage point from which to investigate the Sun and its interaction via the solar wind magnetic fields, plasma, and energetic particles with the geospace system including the Moon itself. The lunar surface and exosphere provide in part a record of solar coronal plasma material input and resultant space weathering over billions of years. The structure and dynamics of solar wind interactions with the Moon provide an accessible near-Earth laboratory environment for study of general solar wind interactions with the vast multitude of airless asteroidal bodies of the inner solar system. Spacecraft in lunar orbit have the often simultaneous opportunity, except when in the Earth's magnetosphere, to make in-situ compositional measurements of the solar wind plasma and to carry out remote observations from the Moon of the solar corona, potentially enabled by lunar limb occultation of the solar disk. The LunaSOX project at NASA Goddard Space Flight Center is addressing these heliophysical science objectives from and of the Moon with support from NASA's Lunar Advanced Science and Exploration Research (LASER) program: (1) specify history of solar wind parameters at and sunward of the Moon through enhanced access (http://lunasox.gsfc.nasa.gov/) to legacy and operational mission data products from the Apollo era to the present, (2) model field and plasma interactions with the lunar surface, exosphere, and wake, as constrained by the available data, through hybrid kinetic code simulations, and (3) advance mission concepts for heliophysics from and of the Moon.

Cooper, John F.↗

Exploring the Potential of Factory Installed Solar + Storage for Homebuilding

In recent years, an increasing number of grid disruptions due to intense weather events, natural disasters, and high peak loads resulted in increased interest in energy-resilient homes. Solar + storage (S+S) as an energy resiliency solution can provide continuity, onsite generation, and backup power during critical events. This project explored factory-installed solar plus storage (FISS) to overcome first cost and installation barriers and bring this resiliency solution to scale for single-family affordable and market-rate homebuyers. Guided by the principles of Lean manufacturing, the team explored how factories building high-performance zero energy modular homes can incorporate S+S into their existing construction system while improving quality and productivity and reducing the costs of the resilient energy system.

ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION,↗

Community Solar for All: Key Findings for State Energy Offices and State LIHEAP Agencies from the Inclusive Shared Solar Initiative

Despite the significant potential for community solar to reduce energy burdens and costs, it has largely remained out of reach for low-income households. While the U.S. community solar market has grown considerably over the last decade, as of December 2022 low to moderate-income (LMI) community solar represented just 2% of the overall market. Effective community solar policies and program decisions can help address this dynamic. State laws, policies, and program rules are critical to the development of community solar programs and projects that are affordable for and cater to the needs of LMI utility customers, who often face disproportionately high energy costs relative to their incomes. This report explores how two sets of state agencies in particular — State and Territory Energy Offices and State Low Income Home Energy Assistance Program (LIHEAP) Agencies —can help to streamline and prioritize the delivery of affordable and accessible shared solar. State Energy Offices are often involved in community solar policy and program design from inception, whether by supporting the enactment of enabling legislation or informing the development of program rules and regulations. State Energy Offices may also be charged with administering or overseeing the implementation of statewide community solar programs and, through the U.S. State Energy Program and other sources of funding, can provide resources and loans that enhance community, developer, and utility confidence and capacity to build, host, and derive value from projects. Relatedly, as implementers of federal LIHEAP block grants, State LIHEAP Agencies have a deep understanding of the needs of lower-income households and can help inform the design and delivery of community solar programs.

14 SOLAR ENERGY↗

Impurity gradients and high efficiency solar cells

One potential means of improving the efficiency of solar cells especially after space irradiation is to incorporate built-in fields into the device through the use of impurity doping gradients. A detailed numerical calculation of solar cell performance has been used to study various types of doping gradients. In general, the predicted improvements in performance have been less than previously reported due to various device effects such as, high injection and the dependence of lifetime on doping density.

Fang, C. R.↗

The development of a method of producing etch resistant wax patterns on solar cells

A potentially attractive technique for wax masking of solar cells prior to etching processes was studied. This technique made use of a reuseable wax composition which was applied to the solar cell in patterned form by means of a letterpress printing method. After standard wet etching was performed, wax removal by means of hot water was investigated. Application of the letterpress wax printing process to silicon was met with a number of difficulties. The most serious shortcoming of the process was its inability to produce consistently well-defined printed patterns on the hard silicon cell surface.

Pastirik, E.↗

Using Behavioral Science to Target LMI and High-Value Solar Installations (Final Technical Report)

This project is a data-driven analysis of approaches to facilitate solar adoption in LMI communities and areas with high potential benefits to the electric grid. The cornerstone of the project was two waves of randomized field experiments. The first wave involved novel approaches to reaching LMI communities based on insights from literature. The second wave involved areas of high potential of solar to the electricity grid, as determined in collaboration with the local utilities in Connecticut. Both waves were followed by surveys to develop insight into the effectiveness of different approaches. A third key element of the project is the development of new agent-based models of solar energy diffusion that explicitly incorporate the real spatial and temporal constraints that influence solar diffusion, based on real-world data on solar adoption. The project also involved outreach and dissemination of key findings to relevant stakeholders, including a guidebook on strategies to accelerate solar deployment to low and moderate income communities, multiple academic publications, and numerous presentations of the research findings.

14 SOLAR ENERGY↗

Small solar thermal electric power plants with early commercial potential

Cost-effective small solar thermal electric power plants (1- to 10-MW nominal size) offer an attractive way of helping the world meet its future energy needs. The paper describes the characteristics of a conceptual near-term plant (about 1 MW) and a potential 1990 commercial version. The basic system concept is one in which steam is generated using two-axis tracking, parabolic dish, and point-focusing collectors. The steam is transported through low-loss piping to a central steam turbine generator unit where it is converted to electricity. The plants have no energy storage and their output power level varies with the solar insolation level. This system concept, which is firmly based on state-of-the-art technology, is projected to offer one of the fastest paths for U.S. commercialization of solar thermal electric power plants through moderate technology advances and mass production.

Jones, H. E.↗

Modeling Time to Failure in Potential-Induced Degradation of Silicon Solar Modules based on Quantitative Sodium Kinetics

We present a physics-based simulation environment for the prediction of potential-induced-degradation (PID) failure time in silicon solar modules. Our model is based on experimental sodium migration kinetics obtained from our recently developed trap-corrected bias-stress-temperature method and from secondary ion mass spectrometry measurements. Furthermore, we model sodium migration to stacking faults and subsequent formation of conductive pathways through the p-n junction, which causes a decrease of the shunt resistance and loss of efficiency.

42 ENGINEERING↗

Investigating Electric Field and Light Induced Degradation in Perovskite Solar Cells through Nanometer-Scale Potential Imaging

Electric field and light induced degradations in perovskite solar cells were evaluated through nanometer-scale potential imaging across the device by using in-situ Kelvin probe force microscopy (KPFM). We derived the electric field profile from potential profiles at different bias voltages to evaluate the locations and quality of junctions across the device. We found relative changes in electric field peak intensity at the HTL/perovskite and perovskite/ETL interfaces upon stressing devices separately under voltage or light. KPFM results during 12-hour stress/rest cycling under electrical bias show both reversible and irreversible changes in the device's interfacial fields. We also observed change in the electric field profile between control and degraded devices after 100 hours of stress/rest cycling under light. Our results demonstrate how nanometer-scale potential imaging can be used to understand the impacts of external electric fields and light soaking on both irreversible degradation and reversible metastability in perovskite solar cells.

Kelvin probe force microscopy↗

LA100 Equity Strategies. Chapter 9: Equitable Community Solar Access and Benefits

The LA100 Equity Strategies project integrates community guidance with robust research, modeling, and analysis to identify strategy options that can increase equitable outcomes in Los Angeles' clean energy transition. This chapter focuses on community solar as a means to provide equitable access to local solar and storage benefits in Los Angeles. Specifically, NREL identified potential community solar sites that could host 30 kilowatts (kW)1 of solar or more and evaluated economic and equity metrics under various program design options. Analysis included a Baseline scenario (business-as-usual) and an Equity scenario, which modeled program enhancements to increase access and benefits to low-income customers. Both scenarios modeled the economics of solar and storage under the LADWP Feed-in Tariff (FiT) program (LADWP 2023b) and the LADWP Feed-in-Tariff Plus Pilot program (LADWP 2023d) compared to a community solar financial model. This research was guided by input from the community engagement process, and associated equity strategies are presented in alignment with that guidance.

14 SOLAR ENERGY↗

Three-dimensional analysis of charging events on days 87 and 114, 1979, from SCATHA

Angular distributions of ions and electrons from the Spacecraft Charging at High Altitudes (SCATHA) were investigated for the floating potential and the differential charging of the spacecraft as deduced from Liouville's theorem. The following was found: (1) short time charging events on the spacecraft are associated with short time increases of the intensity of 10 keV to 1 MeV electrons; (2) short time changes of the spacecraft differential potential are associated with simultaneous short time changes of the spacecraft floating potential; (3) solar UV intensities in penumbra anticorrelate with the spacecraft floating potentials; (4) NASCAP predicts correct forms of sunshade asymmetric surface potentials; (5) certain enhancements of the intensity of energetic ions diminishes the absolute value of the spacecraft surface potential; (6) spacecraft discharging events in times shorter than 20 sec did not change in the spectrum of the energetic plasma; (7) partial discharging of the spacecraft occurred upon entry into a magnetically depleted region; and (8) steady state potentials and transient potentials of duration less than 30 seconds are simulated by the NASCAP code.

Saflekos, N. A.↗

The electric potential of the moon in the solar wind

Acceleration and detection of the lunar thermal ionosphere in the presence of the lunar electric field yields a value of approximately +10 V for the lunar electric potential for solar zenith angles between 20 and 45 deg and in the magnetosheath or solar wind. The ion number density of the thermal ionosphere observed is compatible with a surface neutral number density of about 100,000 atoms/cu cm.

Freeman, J. W., Jr.↗

Modeling of the coupled magnetospheric and neutral wind dynamos

The solar wind interaction with the earth's magnetosphere generates electric fields and currents that flow from the magnetosphere to the ionosphere at high latitudes. Consequently, the neutral atmosphere is subject to the dissipation and conversion of this electrical energy to thermal and mechanical energy through Joule heating and Lorentz forcing. As a result of the mechanical energy stored within the neutral wind (caused in part by Lorentz--and pressure gradient--forces set up by the magnetospheric flux of electrical energy), electric currents and fields can be generated in the ionosphere through the neutral wind dynamo mechanism. At high latitudes this source of electrical energy has been largely ignored in past studies, owing to the assumed dominance of the solar wind/magnetospheric dynamo as an electrical energy source to the ionosphere. However, other researchers have demonstrated that the available electrical energy provided by the neutral wind is significant at high latitudes, particularly in the midnight sector of the polar cap and in the region of the magnetospheric convection reversal. As a result, the conclusions of a number of broad ranging high-latitude investigations may be modified if the neutral-wind contribution to high-latitude electrodynamics is properly accounted for. These include the following: studies assessing solar wind-magnetospheric coupling by comparing the cross polar cap potential with solar wind parameters; research based on the alignment of particle precipitation with convection or field aligned current boundaries; and synoptic investigations attributing seasonal variations in the observed electric field and current patterns to external sources. These research topics have been initiated by satellite and ground-based observations and have been attributed to magnetospheric causes. However, the contribution of the neutral wind to the high-latitude electric field and current systems and their seasonal and local time dependence has yet to be quantitatively evaluated. In this program, we are evaluating the coupled magnetospheric and neutral wind dynamos at high latitudes under various conditions. In addition to examining the impact of seasonal variations, we are investigating the consequences of the separate dynamos having pure current-source or voltage-source behaviors.

Thayer, Jeff P.↗

Transient Thermal Analysis of a Refractive Secondary Solar Concentrator

A secondary concentrator is an optical device that accepts solar energy from a primary concentrator and further intensifies and directs the solar flux. The refractive secondary is one such device; fabricated from an optically clear solid material that can efficiently transmit the solar energy by way of refraction and total internal reflection. When combined with a large state-of-the-art rigid or inflatable primary concentrator, the refractive secondary enables solar concentration ratios of 10,000 to 1. In support of potential space solar thermal power and propulsion applications, the NASA Glenn Research Center is developing a single-crystal refractive secondary concentrator for use at temperatures exceeding 2000K. Candidate optically clear single-crystal materials like sapphire and zirconia are being evaluated for this application. To support this evaluation, a three-dimensional transient thermal model of a refractive secondary concentrator in a typical solar thermal propulsion application was developed. This paper describes the model and presents thermal predictions for both sapphire and zirconia prototypes. These predictions are then used to establish parameters for analyzing and testing the materials for their ability to survive thermal shock and stress.

Geng, Steven M.↗

Electric potential of the moon in the solar wind.

Acceleration and detection of the lunar thermal ionosphere in the presence of the lunar electric field yields a value of at least +10 V for the lunar electric potential for solar zenith angles between approximately 20 and 45 deg and in the magnetosheath or solar wind. An enhanced positive ion flux is observed with the Apollo Lunar Surface Experiments Package Suprathermal Ion Detector Experiment when a preacceleration voltage attains certain values. This enhancement is greater when the moon is in the solar wind as opposed to the magnetosheath.

Freeman, J. W., Jr.↗