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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 1,621 records · Page 90
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

An Overview of the Photovoltaic and Electrochemical Systems Branch at the NASA Glenn Research Center

The Photovoltaic and Electrochemical Systems Branch (LEX) at the NASA Glenn Research Center (GRC) supports a wide variety of space and aeronautics missions, through research, development, evaluation, and oversight.Solar cells, thermal energy conversion, advanced array components, and novel array conceptsLow TRL R&D to component evaluation & flight experimentsSupports NASA missions through PV expertise and facilitiesManagement of SBIR/STTR Topics, Subtopics, and individual efforts.LEX works closely with other NASA organizations, academic institutions, commercial partners, and other Government entities.

Clark, Eric↗
DOE OSTI2022

Phase Identification in Real Distribution Networks with High PV Penetration Using Advanced Metering Infrastructure Data

Many distribution network monitoring and control applications - including state estimation, Volt/VAr optimization, and network reconfiguration - rely on accurate network models; however, the network models maintained by utilities can become outdated because of restoration activities, network reconfiguration, and missing data. With the widespread deployment of advanced metering infrastructure (AMI), abundant measurement data from low-voltage secondary networks are available. The AMI measurement data can be used for phase identification to improve the network models. Although the existing phase identification techniques work well in passive distribution feeders that do not have photovoltaic (PV) generation, they can fail to accurately identify the phases in the presence of PV. This paper proposes a robust phase identification algorithm based on supervised machine learning that accurately identifies the AMI meter phase connectivity in the presence of significant PV generation. The proposed algorithm does not require network topology information or feeder-head measurement data. The algorithm is validated using the AMI measurement data collected in the field and the field-validated phase connectivity database on two real distribution feeders from San Diego Gas & Electric Company that have significant PV generation.

advanced metering infrastructure (AMI)↗
DOE OSTI2024

Leveraging PHIL for Inverter Functionality Requirement Evaluation to Ensure a Reliable Grid

This presentation showcases NREL's ongoing research on advanced Multi-point Power Hardware-in-the-Loop (PHIL) systems, enabling comprehensive evaluation of interoperability, stability, and wide-area stability in complex power grids. Key features include high-power PHIL capabilities, seamless PHIL Interfaces for effortless Grid-Following (GFL) and Grid-Forming (GFM) mode switching, and advanced multi-domain PHIL/Controller Hardware-in-the-Loop (CHIL) capabilities for evaluating diverse technology mixes, facilitating rigorous testing and validation of emerging power systems for reliable integration, enhanced resilience, and optimal performance.

lab capabilities↗
DOE OSTI2021

The Renewable Energy Potential (reV) Model: A Geospatial Platform for Technical Potential and Supply Curve Modeling

The Renewable Energy Potential (reV) model is a platform for detailed assessment of renewable energy (RE) resources and their geospatial intersection with grid infrastructure and land use characteristics. The reV model currently supports photovoltaic (PV), concentrating solar power (CSP) and land-based wind turbine technologies. Modules in the reV framework function at different spatial and temporal resolutions, allowing for assessment of resource potential, technical potential and supply curves at varying levels of detail. The platform runs on NREL's High Performance Computing system, providing scalable and efficient performance from a single location all the way up to continental scales, for a single year or decades of time series resource data. Coupled with NREL's System Advisor Model (SAM), reV supports resource assessment from 5-minute to hourly temporal resolution and provides for analysis of long-term (i.e., year-on-year) variability of RE generation (e.g., interannual variability and exceedance probabilities). Technical potential is measured as a function of resource potential and limitations put on developable land area defined by the user. For example, the user can limit development by land ownership, terrain, land use/cover, and urban areas, as well as custom inputs. Technology, grid interconnection and operation costs, based on the latest market data and future projections, are also embedded in the model. The supply curve module is a spatial sorting algorithm based on plant siting, grid interconnection cost, and regional competition, which provides a geographically discrete estimate of levelized cost of electricity (LCOE) and supply (i.e., capacity) for specific renewable technologies. The reV model currently provides broad coverage across North America, South and Central Asia, South America and South Africa to inform national- and international-scale analyses as well as regional infrastructure and deployment planning.

13 HYDRO ENERGY↗
DOE OSTI2023

Pollen and Bio-Soiling in the Southeast U.S.

Typical PV soiling models presume that soiling follows a sawtooth pattern: linear soiling during dry periods followed by abrupt recovery or cleaning during rainfall events. Due to frequency of rainfall in the in the eastern U.S. sawtooth soiling models report near zero soiling losses in this region. Alternatively, through work with system owner/operators per NREL's PVfleet project it has become clear that there are systems in the Southeast that have soiled as high as 10% which are not recovering with regular rainfall. The current hypothesis is that sticky soiling due to pollen or other biological sources is persistent to rainfall removal. Field data and the latest progress towards de-risking bio-soiling will be presented.

photovoltaic↗
DOE OSTI2020

Decentralized Control of Cascaded H-Bridge Inverters for Medium-Voltage Grid Integration: Preprint

This paper introduces a fully decentralized control strategy that allows for individualized active and reactive power control of H-bridge inverters connected in series. After formulating a model of the system power flows, we outline a communications-free approach where each inverter can act on independent commands. Inverter-level feedback is accomplished locally via a measurement of current flowing through the stack. A key feature is the lack of any centralized control routines or phase-locked loop. In this framework, the reactive power control loops achieve voltage synchronization among the converters and the grid, and the active power control loops modulate the terminal voltage amplitudes that influence power delivery. Furthermore, pole placement via state feedback is used to ensure stability of voltage synchronization while also enabling tracking of bidirectional power commands. Simulations are presented to validate the proposed approach.

communication-free modular converter control↗
DOE OSTI2022

The locational value of distributed energy resources: A parcel-level evaluation of solar and wind potential in New York state

We report distributed energy resources (DERs) are poised to play a significant role in evolving power systems because of their flexibility to be sited in areas of high value to the grid. Traditional DER compensation frameworks, specifically net energy metering (NEM), inadequately communicate differences in the locational and temporal value of DER generation to the grid. As a transition from NEM, New York State's (NYS's) Value of Distributed Energy Resources (VDER) framework provides a methodology for calculating different value components that DERs offer the grid. To study the impacts of VDER frameworks on DER deployment, we developed a model to assess the value of distributed solar and wind systems configured as either a behind-the-meter system or a front-of-the-meter system for each parcel of land in NYS. Using parcel-level granularity, we can closely evaluate DER locational value and siting availability, particularly in urban and suburban settings. Our analysis finds while most DER generators would be modestly compensated for deferred transmission and distribution infrastructure upgrades (~0.01 $\$$/kWh for solar PV), a subset of projects receive significant value from this component (0.035 to 0.089 $\$$/kWh for top 5% of parcels for solar PV). Finally, our analysis finds VDER provides less overall compensation than NEM to the average DER generator, however, it increases access to compensation for front-of-the-meter DERs - a large and emerging market.

14 SOLAR ENERGY↗
DOE OSTI2023

Global horizontal spectral irradiance in Albuquerque - Data and Resources

The Photovoltaic Systems Evaluation Laboratory (PSEL) at Sandia National Laboratories (SNL) in Albuquerque, NM has measured global horizontal spectral irradiance nearly continuously from September 2019 to March 2022. During this time other broadband irradiance measurements (global horizontal, direct normal, diffuse horizontal and global normal) and weather variables were also recorded. For this dataset PV Performance Labs (PVPL) has pulled together data from both sources to assemble a calendar year spectral data set for use in photovoltaic research. It is composed of twelve segments of 15 days each, beginning with January 1-15 and ending with December 1-15. The segments are all taken from the two-year period October 2019 to September 2021.

14 SOLAR ENERGY↗
DOE OSTI2023

Global normal spectral irradiance in Albuquerque - Data and Resources

The Photovoltaic Systems Evaluation Laboratory (PSEL) at Sandia National Laboratories (SNL) in Albuquerque, NM has measured global normal spectral irradiance nearly continuously from August 2013 to April 2018. During this time other broadband irradiance measurements (global horizontal, direct normal, diffuse horizontal and global normal) and weather variables were also recorded. For this dataset PV Performance Labs (PVPL) has pulled together data from both sources to assemble a full calendar year spectral data set for use in photovoltaic research. It is composed of eight continuous segments of different durations taken from the two-year period September 2013 to August 2015.

photovoltaics↗
NASA NTRS1979

Photovoltaic system criteria documents. Volume 2: Quality assurance criteria for photovoltaic applications

Quality assurance criteria are described for manufacturers and installers of solar photovoltaic tests and applications. Quality oriented activities are outlined to be pursued by the contractor/subcontractor to assure the physical and operational quality of equipment produced is included. In the broad sense, guidelines are provided for establishing a QA organization if none exists. Mainly, criteria is provided to be considered in any PV quality assurance plan selected as appropriate by the responsible Field Center. A framework is established for a systematic approach to ensure that photovoltaic tests and applications are constructed in a timely and cost effective manner.

Koenig, John C.↗
DOE OSTI2026

Solar Radiation Research Laboratory (SRRL) Core Project Final Report: Fiscal Years 2022-2024

The Solar Radiation Research Laboratory (SRRL) at the National Laboratory of the Rockies (NLR) is a world-leading solar calibration and measurement facility and maintains and disseminates the World Radiation Reference (essentially the W/m2) for the United States that is essential for traceable and accurate measurements of solar radiation at all solar generation facilities. SRRL operates two calibration facilities that meet International Standards Organization-17025 (ISO-17025) standards and provide unique high-quality calibrations to NREL and other U.S. Department of Energy laboratories. The Baseline Measurement System (BMS) at SRRL provides a high-quality record of solar irradiance and surface meteorological conditions. SRRL capabilities are used to develop (1) improved methods for the calibration of solar radiometers; (2) new standards through the ISO, the International Electrotechnical Commission (IEC), and the American Standards for Testing of Materials (ASTM) International; (c) solar radiation and meteorological models; and (d) advanced instrumentation and methods for operating solar measurement stations. The SRRL datasets are also critical for the validation of new models and datasets, such as the National Solar Radiation Database (NSRDB). The research and development of solar radiation measurement systems and resource modeling techniques are essential for advancing the scientific basis for producing reliable resource data. Specifically, the spatial, temporal, and spectral (wavelength dependency) characteristics of the solar resource are required in several different time frames for various project phases.

14 SOLAR ENERGY↗
DOE OSTI2022

Multiport Control with Partial Power Processing in Solid-State Transformer for PV, Storage, and Fast-Charging Electric Vehicle Integration

This article proposes a multiport control method to enable partial power processing (PPP) in a medium-voltage (MV) multiport solid-state transformer (SST). MV multiport SSTs are promising in integrating low-voltage DC sources or loads such as solar photovoltaic, energy storage, and electric vehicles into smart grids without bulky line-frequency transformers. Compared to voltage-source SST, current-source (CS) SST features single-stage isolated bidirectional AC/AC, AC/DC, or DC/DC conversion using an inductive DC link. For a multiport CS SST, it is revealed in this article that the PPP capability can be enabled through the proposed control without extra hardware, different from the case of voltage-source converters where special hardware architecture is required for the PPP. With the PPP, most power exchange between LV ports is processed by only a fraction of the entire conversion stage, leading to reduced DC-link current, volume, loss, and improved efficiency. The proposed multiport PPP control scheme is analyzed to verify the advantages across a wide voltage and power range against conventional full power processing (FPP) multiport control, using the soft-switching solid-state transformer (S4T) with reduced conduction loss as an example. Comparative experimental results based on a SiC three-port S4T prototype verify the effectiveness of the proposed PPP scheme against the FPP scheme under both steady state and dynamic conditions. Here, the DC-link current reduction is measured to be more than 36%. Significantly, the proposed multiport PPP control scheme is generic and applicable to any hard-switching or soft-switching CS SSTs without extra hardware.

14 SOLAR ENERGY↗
DOE OSTI2023

Life-cycle costing assessment of back contact doping and encapsulation alternatives for increasing the life expectancy of CdTe PV modules (Final Report)

Contribution of Research to the State-of-Knowledge This research produced comparative sustainability evaluations of back contact doping and encapsulation alternatives considered by First Solar for decreasing degradation and increasing the life of the cadmium telluride (CdTe) photovoltaic (PV) modules. Technical Effectiveness and Economic Feasibility of Methods Investigated A holistic life-cycle-assessment of the alternatives considered for longer module operational lives, showed that they add between 0.2% and 2% to environmental impact indicators at the cradle-to-gate module level, but at the cradle-to-grave system level, alternative materials offer only benefits (i.e., environmental impact indicator decreases) to the public and the environment. Parallel experimental studies at First Solar showed that the use of the considered alternative materials did not impact the effectiveness of the current module recycling separations and material recovery processes. Furthermore, the increment on the module manufacturing cost due to using alternative materials was estimated to be negligible (i.e., >1%) and longer module lives more than compensate cost increases. Specifically, increase of the current warranted module life of 30 years to 50 years, would decrease the levelized cost of electricity (LCOE) from $40/MWh to $24/MWh for utility-scale installations in the US-SW, the economic feasibility of the considered alternatives is assured. Benefit to the Public With decreasing degradation from the current ~0.3%/year of Series 6 modules to less than 0.2%/year, the public will be benefited by longer photovoltaic operational lives, and therefore. In addition, the requirement for end-of-life management is shifted from 30 years to 40 or 50 years, with profound benefits to the public and the environment.

14 SOLAR ENERGY↗
NASA NTRS2008

Advanced Solar Cell and Array Technology for NASA Deep Space Missions

A recent study by the NASA Glenn Research Center assessed the feasibility of using photovoltaics (PV) to power spacecraft for outer planetary, deep space missions. While the majority of spacecraft have relied on photovoltaics for primary power, the drastic reduction in solar intensity as the spacecraft moves farther from the sun has either limited the power available (severely curtailing scientific operations) or necessitated the use of nuclear systems. A desire by NASA and the scientific community to explore various bodies in the outer solar system and conduct "long-term" operations using using smaller, "lower-cost" spacecraft has renewed interest in exploring the feasibility of using photovoltaics for to Jupiter, Saturn and beyond. With recent advances in solar cell performance and continuing development in lightweight, high power solar array technology, the study determined that photovoltaics is indeed a viable option for many of these missions.

Piszczor, Michael↗
DOE OSTI2022

Investigating Local Carrier Dynamics in PERC Patterned CdTe Solar Cells

Remarkable progress has been achieved in CdTe photovoltaics (PVs) to further improve cell performance while reducing manufacturing costs. Researchers optimized the front contact that leads the short-circuit current density (J sc ) over 31mA/cm 2 (e.g., (Zn, Mg)O buffer layer and/or alloying CdTe with Se). Reese et al. reported an open-circuit voltage (V oc ) over 1 V with group-V doped single crystal, showing the feasibility of increasing V oc in CdTe PV that is fixed to less than 900 mV in most cases. Recent studies suggested that the V oc improvement in polycrystalline CdTe PVs requires well-passivated back contact. One possible strategy is to use CdMgTe alloy (E g > 1.8 eV), where the band-gap offset (ΔE CB ≈ 0.2 eV) reflects minority carrier electrons, thereby decreasing surface recombination. Another strategy is to utilize a stable Al 2 O 3 layer as an electron reflector; experimental works confirmed the improved performance with a conformal Al 2 O 3 layer. In this configuration, the precise control of Al 2 O 3 (≈1 nm) over the entire CdTe layer is essential because the J sc greatly depends on the tunneling current. While promising, both CdMgTe and Al 2 O 3 passivation on CdTe introduce unfavorable valence band offset that blocks the hole transport. Kephart et al. proposed a patterned passixc vation layer (≈ 20 nm Al 2 O 3 ) with point contacts (≈ 3 μm in diameter) that extract hole carriers. This configuration is similar to the passive emitter and rear contact (PERC) design that has been extensively studied in Si PVs. While remarkably high carrier lifetime and photoluminescence (> 10 X) were measured, consistent improvement in V oc and efficiency in this CdTe PERC were not yet observed. At this time, it is unclear how the surface potential is distributed in the presence of patterned Al 2 O 3 reflectors and how this additional field impacts the PV performance for Cu-doped and group-V doped CdTe PERC devices. To tackle this challenge, we develop robust nanofabrication and characterization platform to study CdTe PERC devices consisting of a patterned Al 2 O 3 layer on CdSe( 1-x )Te x (Cu-doped, GrV-doped; x = 0 to 1; CST). First Solar supplies high-quality CST materials. The dark and light I-Vs under 1-sun illumination are extracted for a series of each set of devices. We perform quantitative and qualitative PV analysis for a series of Cu-doped and Gr-V doped PERC devices, showing notably different V oc changes for GrV-doped compared to Cu-doped PERC devices. This project attempts to produce individual contacts on single grains and grain boundaries to measure lateral transport. As a model system, we use a CdSe( 1-x )Te x film on glass prepared by a colossal grain growth (CGG) technique at National Renewable Research Laboratories (NREL). Our preliminary results confirm that intergranular transport is hindered by the electrical barrier formed near grain boundaries. The PERC fabrication and the lateral transport measurement platform developed in this project can easily be applied to other types of advanced CdSe( 1-x )Te x architectures to better understand local photocarrier transport, in turn, providing the fundamental knowledge to improve the performance of CdTe PVs.

14 SOLAR ENERGY↗