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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Cybersecurity Assessment for a Behind-the-Meter Solar PV System: A Use Case for the DER-CF

The world's energy production is shifting toward lower-cost, cleaner, more efficient, and sustainable sources. The increasing numbers of distributed energy resources (DERs) are allowing for the rapid transformation of electric grids toward achieving the goal of energy decarbonization. Along with cleaner and more efficient energy, however, we must also aim for a secure energy future. Solar photovoltaic (PV) systems are an important part of this transition. This paper discusses a cybersecurity risk assessment for behind-the-meter DERs using a solar PV system as a use case of the Distributed Energy Resource Cybersecurity Framework (DER-CF) developed by the National Renewable Energy Laboratory. This poster presents a conference paper on the risk assessment processes and summarizes the DER-CF's use case recommendations to strengthen the cybersecurity posture of the electric grid.

cybersecurity↗
DOE OSTI2023

Expanding Solar Access: State Community Solar Landscape (2022)

This report supports the NCSP 2025 goal by documenting existing state-level community solar policies and programs. Although the purpose of this report is to present the existing market and policy status for community solar, with increasing attention on expanding access to solar energy for LMI customers, we also discuss key considerations for incorporating energy justice into community solar policies.

14 SOLAR ENERGY↗
DOE OSTI2017

Electron–Ion Intensity Dropouts in Gradual Solar Energetic Particle Events during Solar Cycle 23

Since the field-line mixing model of Giacalone et al. suggests that ion dropouts cannot happen in the “gradual” solar energetic particle (SEP) event because of the large size of the particle source region in the event, the observational evidence of ion dropouts in the gradual SEP event should challenge the model. We have searched for the presence of ion dropouts in the gradual SEP event during solar cycle 23. From 10 SEP events the synchronized occurrence of ion and electron dropouts is identified in 12 periods. Our main observational facts, including the mean width of electron–ion dropout periods being consistent with the solar wind correlation scale, during the dropout period the dominance of the slab turbulence component and the enhanced turbulence power parallel to the mean magnetic field, and the ion gyroradius dependence of the edge steepness in dropout periods, are all in support of the solar wind turbulence origin of dropout events. Also, our observation indicates that a wide longitude distribution of SEP events could be due to the increase of slab turbulence fraction with the increased longitude distance from the flare-associated active region.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2023

Simulation of the Solar Energetic Particle Event on 2020 May 29 Observed by Parker Solar Probe

This paper presents a stochastic three-dimensional focused transport simulation of solar energetic particles (SEPs) produced by a data-driven coronal mass ejection (CME) shock propagating through a data-driven model of coronal and heliospheric magnetic fields. The injection of SEPs at the CME shock is treated using diffusive shock acceleration of post-shock suprathermal solar wind ions. A time-backward stochastic simulation is employed to solve the transport equation to obtain the SEP time–intensity profile at any location, energy, and pitch angle. The model is applied to a SEP event on 2020 May 29, observed by STEREO-A close to ∼1 au and by Parker Solar Probe (PSP) when it was about 0.33 au away from the Sun. The SEP event was associated with a very slow CME with a plane-of-sky speed of 337 km s −1 at a height below 6 RS as reported in the SOHO/LASCO CME catalog. We compute the time profiles of particle flux at PSP and STEREO-A locations, and estimate both the spectral index of the proton energy spectrum for energies between ∼2 and 16 MeV and the equivalent path length of the magnetic field lines experienced by the first arriving SEPs. We find that the simulation results are well correlated with observations. The SEP event could be explained by the acceleration of particles by a weak CME shock in the low solar corona that is not magnetically connected to the observers.

Solar energetic particles↗
DOE OSTI2020

India Solar Resource Data: National Solar Radiation Database (NSRDB)

The National Solar Radiation Database (NSRDB) provides high-resolution solar radiation data for long periods of time, which allows user to have a clear understanding of the spatial and temporal correlation of the data to determine the true impact of solar variability on the grid. This fact sheet specifically outlines solar resource data for India included in NSRDB.

energy systems↗
DOE OSTI2025

Solar Modulation of Cosmic Nuclei over a Solar Cycle: Results from the Alpha Magnetic Spectrometer

We report the properties of precision time structures of cosmic nuclei He, Li, Be, B, C, N, and O fluxes over an 11-year solar cycle from May 2011 to November 2022 in the rigidity range from 1.92 to 60.3 GV. The nuclei fluxes show similar but not identical time variations with amplitudes decreasing with increasing rigidity. In particular, below 3.64 GV the Li, Be, and B fluxes, and below 2.15 GV the C, N, and O fluxes, are significantly less affected by solar modulation than the He flux. We observe that these differences in solar modulation are linearly correlated with the differences in the spectral indices of the cosmic nuclei fluxes. This shows, in a model-independent way, that solar modulation of galactic cosmic nuclei depends on their spectral shape. In addition, solar modulation differences due to nuclei velocity dependence on the mass-to-charge ratio (𝐴/𝑍) are not observed.

cosmic ray composition & spectra↗
DOE OSTI2025

First observations of solar halo gamma rays over a full solar cycle

We analyze 15 years of Fermi-LAT data and produce a detailed model of the Sun’s inverse-Compton scattering emission (solar halo), which is powered by interactions between ambient cosmic-ray electrons and positrons with sunlight. By developing a novel analysis method to analyze moving sources, we robustly detect the solar halo at energies between 31.6 MeV and 100 GeV, and angular extensions up to 45° from the Sun, providing new insight into spatial regions where there are no direct measurements of the Galactic cosmic-ray flux. The large statistical significance of our signal allows us to subdivide the data and provide the first 𝛾-ray probes into the time variation and azimuthal asymmetry of the solar modulation potential, finding time-dependent changes in solar modulation both parallel and perpendicular to the ecliptic plane. Our results are consistent with (but with independent uncertainties from) local cosmic-ray measurements, unlocking new probes into astrophysical processes near the solar surface.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1971

Silicon solar cells as a high-solar-intensity radiometer

The characteristics of a conventional, 1- by 2-cm, N/P, gridded silicon solar cell when used as a radiometer have been determined for solar intensity levels to 2800 mW/sq cm (20 solar constants). The short-circuit current was proportional to the radiant intensity for levels only to 700 mW/sq cm (5 solar constants). For intensity levels greater than 700 mW/sq cm, it was necessary to operate the cell in a photoconductive mode in order to obtain a linear relation between the measured current and the radiant intensity. When the solar cell was biased with a reverse voltage of -1 V, the measured current and radiant intensity were linearly related over the complete intensity range from 100 to 2800 mW/sq cm.

Spisz, E. W.↗
NASA NTRS1972

Photovoltaic solar array technology required for three wide scale generating systems for terrestrial applications: rooftop, solar farm, and satellite

Three major options for wide-scale generation of photovoltaic energy for terrestrial use are considered: (1) rooftop array, (2) solar farm, and (3) satellite station. The rooftop array would use solar cell arrays on the roofs of residential or commercial buildings; the solar farm would consist of large ground-based arrays, probably in arid areas with high insolation; and the satellite station would consist of an orbiting solar array, many square kilometers in area. The technology advancement requirements necessary for each option are discussed, including cost reduction of solar cells and arrays, weight reduction, resistance to environmental factors, reliability, and fabrication capability, including the availability of raw materials. The majority of the technology advancement requirements are applicable to all three options, making possible a flexible basic approach regardless of the options that may eventually be chosen. No conclusions are drawn as to which option is most advantageous, since the feasibility of each option depends on the success achieved in the technology advancement requirements specified.

Berman, P. A.↗
NASA NTRS1973

Solar flare observations and solar flare models

The use of solar flare models based on specific and detailed observations of solar flares is discussed. A process for determining the validity of various solar models is analyzed. The process relegates the infall-impact model for flares to a secondary role in high energy solar events. The strictly thermal infall-impact model cannot lead to temperatures greater than five million degrees K. Another process is needed to explain the high energy aspects of solar flares which are related to temperatures equal to or greater than 10 to the 7th power degrees K, nonthermal X-ray and radio emissions, white light flares, high energy particles from the sun, and gamma ray producing particles in the sun.

Hyder, C. L.↗
NASA NTRS1974

A possible correlation between maxima of the far ultraviolet solar irradiance and central meridian passages of solar magnetic sector boundaries

Satellite observations of the sun over almost five years have shown that principally two UV active longitudes have persisted over a significant portion. A comparison between the position of solar magnetic sector boundaries and UV enhancements of the sun indicates that the UV maxima tend to occur near the times when a solar sector boundary is near central meridian. An estimate of the magnitude of the variable UV solar energy input into the atmosphere resulting from the rotation of active solar longitudes is that for wavelengths less than 175 nm and down to H. Lyman-alpha it exceeds the annual variation, whereas at longer wavelengths it is less. The total observed peak-to-peak variation in the UV irradiance from 120 to 300 nm over a solar rotation is typically at least 230 ergs/sq cms.

Heath, D. F.↗
NASA NTRS1975

Flat-Plate Solar-Collector Performance Evaluation with a Solar Simulator as a Basis for Collector Selection and Performance Prediction

The use of a solar simulator for performance determination permits collector testing under standard conditions of wind, ambient temperature, flow rate and sun. The performance results determined with the simulator have been found to be in good agreement with outdoor performance results. The measured thermal efficiency and evaluation of 23 collectors are reported which differ according to absorber material (copper, aluminum, steel), absorber coating (nonselective black paint, selective copper oxide, selective black nickel, selective black chrome), type of glazing material (glass, Tedlar, Lexan, antireflection glass), the use of honeycomb material and the use of vacuum to prevent thermal convection losses. The collectors were given performance rankings based on noon-hour solar conditions and all-day solar conditions. The determination with the simulator of an all-day collector performance was made possible by tests at different incident angles. The solar performance rankings were made based on whether the collector is to be used for pool heating, hot water, absorption air conditioning, heating, or for a solar Rankine machine.

Simon, F. F.↗
NASA NTRS1975

H-alpha synoptic charts of solar activity during the first year of solar cycle 20, October 1964 - August 1965

Solar activity during the period October 28, 1964 through August 27, 1965 is presented in the form of charts for each solar rotation constructed from observations made with the chromospheric H-alpha spectra line. These H-alpha synoptic charts are identical in format and method of construction to those published for the period of Skylab observations. The sunspot minimum marking the start of Solar Cycle 20 occurred in October, 1964; therefore, charts represent solar activity during the first year of this solar cycle.

Mcintosh, P. S.↗
NASA NTRS1974

A search for solar neutrons during solar flares

A new upper limit to the 1-20 MeV neutrons produced at the sun during large solar flares was obtained as a result of measurements made by a neutron detector on board the OGO-6 satellite. It was found that the 1-20 MeV solar neutron flux for the Nov. 2, June 13, June 15, Sept. 25, and Dec. 19, 1969, solar flare events cannot be greater than 0.05 n per sq cm per sec at the 95% confidence level. These measurements are consistent with the models proposed by Lingenfelter (1969) and Lingenfelter and Ramaty (1967) for solar neutron production during solar flares.

Ifedili, S. O.↗
NASA NTRS1976

The 3-D solar radioastronomy and the structure of the corona and the solar wind

The mechanism causing solar radio bursts (1 and 111) is examined. It is proposed that a nonthermal energy source is responsible for the bursts; nonthermal energy is converted into electromagnetic energy. The advantages are examined for an out-of-the-ecliptic solar probe mission, which is proposed as a means of stereoscopically viewing solar radio bursts, solar magnetic fields, coronal structure, and the solar wind.

Steinberg, J. L.↗
NASA NTRS1976

Solar-wind tritium limit and the mixing rate of the solar atmosphere

Tritium has been measured, in Surveyor 3 samples, some of which were adjacent to those in which solar-wind-implanted He-4 had previously been measured. Little of the H-3 can be attributed to solar-wind implantation. The upper limit for the H-3/He-4 ratio in the solar wind is four times ten to the minus tenth power and corresponds to a H-3/H-1 limit of two times ten to the minus eleventh power. This limit imposes a requirement on the mixing rate in the solar atmosphere if the H-3 production rate in solar-surface nuclear reactions is greater than 160 sq cm/sec.

Fireman, E. L.↗
NASA NTRS1977

A search for a general gradient in the solar wind speed at low solar latitudes

Long-term averages of solar-wind-speed data obtained in the ecliptic plane from July 1964 through December 1975 have been examined for a regular variation in flow speed associated with earth's yearly excursion to latitudes of plus or minus 7.25 deg about the solar equator. Regular speed modulations of about 70 km/s peaking at the highest latitudes are discernible from mid-1964 through 1966 and from early 1969 to early 1971. During the remainder of this 11.5-year interval, the modulations in speed seem to be aperiodic. A superposed epoch analysis of all the data fails to reveal a general solar latitude gradient in the solar-wind flow for these 11.5 years. It is concluded that with near-earth observations, a latitude dependence of the flow speed is too small to be detected on a regular basis against a background 'noise' of solar-wind streams, which vary in longitude, latitude, and time.

Bame, S. J.↗
NASA NTRS1976

Solar wind H-3 and C-14 abundances and solar surface processes

Tritium is measured as a function of depth in a Surveyor 3 sample. The upper limit for solar-wind-implanted tritium gives an H-3/H-1 limit for the solar wind of 10 to the -11th power. The temperature-release patterns of C-14 from lunar soils are measured. The C-14 release pattern from surface soils differs from a trench-bottom soil and gives positive evidence for the presence of C-14 in the solar wind with a C-14/H-1 ratio of approximately 6 by 10 to the -11th power. This C-14 content fixes a minimal magnitude for nuclear processes on the solar surface averaged over the past 10,000 yr. The H-3 and C-14 contents combine to require that either the mixing rate above the photosphere be rapid or that the H-3 produced by nuclear reactions be destroyed by secondary nuclear reactions before escaping in the solar wind.

Fireman, E. L.↗