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At least 109 records · Page 6

Solar Farm Development Impacts on Eastern Box Turtle ( Terrapene carolina ) Home Ranges

Eastern Box Turtle (Terrapene carolina) populations have declined drastically since 1970 because of continued destruction and fragmentation of their habitat. Although they are known to shift their home ranges because of environmental degradation, it is unknown how solar arrays impact Eastern Box Turtles. From 2011–2018, we collected data on Eastern Box Turtle movement and occupancy in a 79-ha solar farm. The solar farm is divided into six fenced areas, each containing wildlife openings for movement of terrestrial fauna every 23 m around the fenced solar arrays. For this work, we hypothesized that the solar arrays changed the home range sizes of turtles that interacted with the field. We fitted 41 Eastern Box Turtles with radio transmitters and tracked their locations twice per week in June–August from 2011–2018. Seventeen turtles had home ranges that overlapped with the solar arrays whereas 24 turtles had home ranges that never interacted with the solar arrays. We calculated home range sizes and tested for differences between overlapping and nonoverlapping groups. We further considered if the number of observations within the solar farm impacted home range size and displacement. We found that Eastern Box Turtles that used the solar farm exhibited 55–83% larger home ranges on average than turtles in natural habitats, but there was no significant association of home range size with the amount of time observed within the solar farm. Finally, we discuss strategies to mitigate negative impacts of solar farm development on turtles.

Radio telemetry↗

Cybersecurity Standards for Photovoltaic Operations

Solar energy plays an important role in securing a more resilient, cyber-secure electrical grid in Pennsylvania. Solar's ability to be widely "distributed" on residential and large roofs, marginal lands, and many other locations across Pennsylvania - as opposed to being centralized - offers a strong option for addressing the myriad of potential disruptions that can occur to the grid's infrastructure. And when combined with energy storage, local energy needs can be met immediately without having to wait on the delivery of an off-site fuel source. As more and more distributed solar electricity generation is brought online, researchers, technology developers, solar developers and grid operators are paying close attention to the potential for solar to enhance grid cybersecurity. Although nobody may know when, where, or how the next cyberattack will take place, there are security measures, technical solutions, and management practices that are being implemented across the industry to protect against network control issues and grid operations. Everyone participating in the solar value chain stands to gain from a coordinated, iterative approach to protect against cyber vulnerabilities and build deeper resilience into the architecture of our grid.

cybersecurity↗

SEP solar array development testing

This paper describes the test program of a lightweight 25 kW solar array for solar electric propulsion. A full-scale development wing was made of aluminum with the containment box cover of graphite-epoxy, while the flight design array wing uses a graphite-epoxy structure. The full-scale continuous longeron array extension mast was tested for performance on a water table, and the full scale wing was functionally tested to demonstrate automatic containment box unlocking, wing extension, and retraction, blanket tensioning, and automatic application of blanket preload. The wing was then tested to the Shuttle acoustic environment, followed by a thermal/vacuum test in which the wing was extended and retracted at high and low temperature. Finally, the wing was tested in vibration with sine and random vibration environments.

Elms, R. V., Jr.↗

Peeled film GaAs solar cell development

Thin-film, single-crystal gallium arsenide (GaAs) solar cells could exhibit a specific power approaching 700 W/kg including coverglass. A simple process has been described whereby epitaxial GaAs layers are peeled from a reusable substrate. This process takes advantage of the extreme selectivity of the etching rate of aluminum arsenide (AlAs) over GaAs in dilute hydrofluoric acid. The feasibility of using the peeled film technique to fabricate high-efficiency, low-mass GaAs solar cells is presently demonstrated. A peeled film GaAs solar cell was successfully produced. The device, although fractured and missing the aluminum gallium arsenide window and antireflective coating, had a Voc of 874 mV and a fill factor of 68 percent under AM0 illumination.

Wilt, D. M.↗

Heat engine development for solar thermal power systems

The technical status of three heat engines (Stirling, high-temperature Brayton, and Combined cycle) for use in solar thermal power systems is presented. Performance goals necessary to develop a system competitive with conventional power requirements include an external heated engine output less than 40 kW, and efficiency power conversion subsystem at least 40% at rated output, and a half-power efficiency of at least 37%. Results show that the Stirling engine can offer a 39% efficiency with 100 hours of life, and a 20% efficiency with 10,000 hours of life, but problems with seals and heater heads exist. With a demonstrated efficiency near 31% at 1500 F and a minimum lifetime of 100,000 hours, the Brayton engine does not offer sufficient engine lifetime, efficiency, and maintenance for solar thermal power systems. Examination of the Rankine bottoming cycle of the Combined cycle engine reveals a 30 year lifetime, but a low efficiency. Additional development of engines for solar use is primarily in the areas of components to provide a long lifetime, high reliability, and low maintenance (no more than $0.001/kW-hr).

Pham, H. Q.↗

JPL lithium doped solar cell development program

One of the most significant problems encountered in the use of silicon solar cells in space is the sensitivity of the device to electron and proton radiation exposure. The p-diffused-into-n-base solar cells were replaced with the more radiation tolerant n-diffused-into-p-base solar cells. Another advancement in achieving greater radiation tolerance was the discovery that the addition of lithium to n-base silicon resulted in what appeared to be annealing of radiation-induced defects. This phenomenon is being exploited to develop a high efficiency radiation resistant lithium-doped solar cell. Lithium-doped solar cells fabricated from oxygen-lean and oxygen-rich silicon were obtained with average initial efficiencies of 11.9% at air mass zero and 28 C, as compared to state-of-the-art n-p cells fabricated from 10 ohm cm silicon with average efficiencies of 11.3% under similar conditions. Lithium-doped cells demonstrated the ability to withstand three to five times the fluence of 1-MeV electrons before degrading to a power equivalent to state-of-the-art solar cells. The principal investigations are discussed with respect to fabrication of high efficiency radiation resistant lithium-doped cells, including starting material, p-n junction diffusion, lithium source introduction, and lithium diffusion.

Berman, P. A.↗

A field gas chromatograph using technology developed for solar system exploration

Trace gas analysis is an integral part of biospheric studies. Analytical instruments, primarily gas chromatographs (GC), are capable of measuring gases and volatiles to the ppb-level in real time. Trace gases significant in the study of biocycles include nitrous oxide, hydrogen sulfide, other nitrogen and sulfur species, as well as methane and ethylene. The concept of a field gas chromatograph is derived from technology being pursued in the design of ultra-compact instruments for solar system exploration. The instrument breadboard incorporates the specialized porous column packings and the highly sensitive metastable ionization detector developed by the Solar System Exploration Office. These parts ensure a broad capability for which the analysis of ambient N2O is one example. A commercial, portable gas chromatograph is currently being extensively modified to incorporate analytical concepts and components derived from flight GC technology. Data storage devices suitable for field use are presently being studied.

Woeller, F. H.↗

Vegetation Change Detection in Southern California Solar Energy Developments

Change detection from satellite sensor vegetation indices (VIs) presents an opportunity to monitor trends and disturbances at the regional scale for southern California's Mojave and Lower Colorado Deserts. Renewable energy sites are being constructed in this region on public lands under the Bureau of Land Management (BLM). We have developed a framework for VI change detection over the past two decades, with initial focus on three sites, Joshua Tree National Park, Mojave National Preserve, and a proximal group of Development Focus Areas (DFAs), for comparison between protected and development-targeted lands. Three Terra MODIS VIs (normalized difference [NDVI], enhanced [EVI], soil-adjusted [SAVI]) were evaluated in the Breaks for Additive Season and Trend (BFAST) setting for the regional MODIS 250-m resolution grid to estimate significant time series shifts (breakpoints) from February 2000 to May 2018. All three VIs tended to detect the maximum number of breakpoints at a grid location, but cross-correlations with precipitation and comparison with timing of wildfire burns near the study sites for breakpoint density (proportion of area with a breakpoint) showed that NDVI had the strongest response to these major disturbances, supporting its use for subsequent analysis. Time series of NDVI breakpoint change densities for individual solar energy sites did not have a consistent vegetation response following construction. Bootstrapping showed that the DFAs had significantly larger kurtosis and variance in the positive NDVI breakpoint distribution than did the protected sites, but there was no significant difference in the negative distribution for all three sites. The inconsistent post-construction NDVI signal and the large number of breakpoints overall suggested that the largest changes in vegetation cover density were tied to seasonal precipitation amounts. The distributional results indicated that existing site-specific conditions were the main control on VI responses, given the history of human disturbances in the DFAs. Although the results do not support persistent VI disturbances resulting from recent solar energy development, continued monitoring and examination of other ecological variables and surface temperatures will be vital to the long-term protection of this desert environment.

Potter, Christopher S.↗

Activities in space-based solar power development

Two space-based power concepts are considered. The satellite solar power system concept employs a large solar cell array to convert solar energy to electrical energy. The energy, in the form of microwaves, is transmitted to the ground where it is converted to dc power and transmitted to the utility network. According to the power relay satellite concept, power is generated on the ground at large stations in remote areas. The generated power in the form of microwaves is beamed for distribution to a relay satellite. Studies related to an investigation of the feasibility of the two concepts are briefly discussed.

Whitacre, W. E.↗

Solar Energy Development on the FSST Reservation

FSST undertook this project to install PV solar with the goal of reducing retail power consumption at 11 Tribal buildings. A combined total of 318kW has been installed over these sites and power savings are being recorded on a regular basis. The Tribe entered into the project with several specific objectives that made this a unique effort. First of all, all of the systems were installed by Tribal maintenance personnel with some technical support. This model had been developed with previous projects that Nebraska Renewable Energy Systems (NRES) had completed and had shown great success. This approach helped to ensure we met the DOE goal of ‘building capacity’ within the Tribe. There was some skepticism about this model in Flandreau at the onset of discussions, but the excellent final results spoke for themselves! A second objective was to overcome the sore lessons that were learned after FSST invested in early deployment of pole mounted solar systems that were not sturdy enough for SD winds. It was a very courageous decision to move forward again with solar pole mounts (and other types) in this very high wind area. We shall report that the Tribe was fully successful in achieving what they set out to do there. The final major objective was to deploy the PV Solar systems in such a way as to integrate them into their surroundings wherever possible. In some cases the mounting choice was clear, but in several locations, the system was designed to be a functional and aesthetically enhancing part of their surroundings. These elevated systems allowed the PV system to act as a shade structure and create useful space under them as well as making power. FSST had these elevated ground mount systems specially designed for our application by Ironridge and were rated for the tough winds of South Dakota (120MPH+).

14 SOLAR ENERGY↗

Development of Thin Solar Cells for Space Applications at NASA Glenn Research Center

NASA GRC Thin Film Solar Cell program is developing solar cell technologies for space applications which address two critical metrics: higher specific power (power per unit mass) and lower launch stowed volume. To be considered for space applications, an array using thin film solar cells must offer significantly higher specific power while reducing stowed volume compared to the present technologies being flown on space missions, namely crystalline solar cells. The NASA GRC program is developing single-source precursors and the requisite deposition hardware to grow high-efficiency, thin-film solar cells on polymer substrates at low deposition temperatures. Using low deposition temperatures enables the thin film solar cells to be grown on a variety of polymer substrates, many of which would not survive the high temperature processing currently used to fabricate thin film solar cells. The talk will present the latest results of this research program.

Dickman, John E.↗

Multi-100 kW: Planar low cost solar array development

The development of a 100 kW planar low cost solar array is presented. Tasks are defined, objectives are stated, and test results are given. A study of alternate contact configuration concluded that gridded back contact cells sharply reduced solar absorptance, that copper contacts will require a developmental program before interface can be achieved, and that gridded back contact cells using Ti-Pd-Ag as the contact materials appear to be the most cost-effective design.

Source record↗

The Development of Solar Sail Propulsion for NASA Science Missions to the Inner Solar System

This paper examines recent assessments of the technology challenges facing solar sails, identifies the systems and technologies needing development, and the approach employed by NASA's In-space Propulsion Program in NASA to achieve near term products that move this important technology from low technology readiness level (TRL) toward the goal of application to science missions in near earth space and beyond. The status of on-going efforts to design, build, and test ground demonstrators of alternate approaches to structures (inflatable versus rigid), membrane materials, optical shape sensing, and attitude control will be presented along with planned future investments.

Montgomery, Edward E, IV↗

Development of Solar Sail Propulsion for Inner Solar System NASA Science Missions

This paper examines recent assessments of the technology challenges facing solar sails, identifies the systems and technologies needing development, and the approach employed by NASA's In-Space Propulsion program in NASA to achieve near-term products that move this important technology from low technology readiness level toward the goal of application to science missions in near-Earth space and beyond.

Montgomery, Edward E., IV↗

Solar cell development for the power extension package

The PEP is a 32 kilowatt flexible substrate, retrievable, solar array system for use on the Space Shuttle. Solar cell costs will be reduced by increasing cell area and simplifying cell and coverglass fabrication processes and specifications. The cost goal is to produce cells below $30 per watt. Two and ten ohm-cm silicon cells were investigated. In phase I of the cell development program a few thousand candidate cells will be produced and evaluated for utility and quality. In phase II a large number of cells will be fabricated to verify production readiness and cell yields and costs. This schedule is compatible with PEP initial operational capability in 1984. Approximately 140,000 large area (5.9 x 5.9 cm) cells will be required for two PEP solar arrays. The status of the cell development and testing, including a radiation damage test and side-by-side comparison of candidate cell types with pre- and post-irradiation airplane calibration of outer space short-circuit current, is reported.

Baraona, C. R.↗