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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 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Stabilization of light-induced effects in Si modules for IEC 61215 design qualification

Standardized testing of commercial photovoltaic modules is widely used around the world and decreases risks of module failures. Such testing also reduces financial risks for module manufacturers and customers. This work examines the expected impact of certain defects in silicon (Si) modules during standardized accelerated testing. Specifically, the behavior of boron-oxygen (BO) light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) are simulated during some of the stress tests in IEC 61215. LID and LeTID reaction rates at qualification temperatures are estimated from earlier published data. It is demonstrated the BO-related LID may cause some false positives and false negatives when IEC 61215 tests are performed as prescribed in the 2016 published version. Possible stabilization steps to avoid these false results are suggested. State changes for the defects causing LeTID occur much more slowly than those causing BO LID, and therefore LeTID is predicted to have a lesser impact on the IEC 61215 stress tests results.

14 SOLAR ENERGY↗
DOE OSTI2022

Manufacturing Supply Chain Development for Modular Solar-Thermochemical Conversion Platform - CRADA 387 (Final Report)

Modular chemical process intensification (MCPI) is an emerging field where chemical processing is performed using small-scale modular equipment instead of conventional large centralized chemical plants. Conventional chemical plants benefit from economies of scale that encourage scale-up to ever larger plants. A goal of MCPI is to develop technology that intensifies processing so that equipment can be dramatically smaller and integrated into modular systems. Scale-up occurs by adding more modules in parallel rather than making the equipment larger. A key concept is that equipment and modules can ultimately be cheaper by leveraging economies of mass production, analogous to the automotive industry, in manufacturing the equipment. This project made significant progress toward this outcome by meeting the RAPID institute metric to reduce equipment cost by 20% for each doubling in manufacturing volume. The MCPI application was thermochemical technology that is being commercialized by STARS Technology Corporation, one of the CRADA partners. The technology converts solar and renewable power to chemical energy to produce renewable hydrogen, fuels, and chemicals. The benefit to the public is reduction in greenhouse gases that are contributing to climate change. The project transitioned the steam methane reforming (SMR) reactor from conventional fabrication methods to additive manufacturing (AM) direct metal laser sintering (DMLS) process. This is projected to reduce the cost of making a reactor by 58% when producing 100 reactors per year. Innovations in the DMLS process produced a patented design that reduces reactor weight by 60%. Reductions in material costs and processing time extend the DMLS advantage to higher production volumes. The new design promises to be 38% cheaper than the conventional processes at 1000 units per year. The resulting 87% reduction in the steam methane reforming (SMR) module cost in scaling from current costs meets the RAPID metric. The project was successful in producing and testing the first ever additively manufactured SMR reactors. A reactor achieved over 82% efficiency in converting electric power to chemical energy, which is a world record for an inductively heated SMR. The project has contributed to the design and assembly of a first demonstration plant that is headed to a hydrogen bus filling station in Thousand Palms, CA.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

US DOE Regional Test Centers Program - 2016 Annual Report.

The US Department of Energy’s Regional Test Center (RTC) program provides outdoor validation and bankability data for innovative solar technologies at five sites across the US representing a range of climate conditions. Data helps get new technologies to market faster and improves US industry competitiveness. Managed by Sandia National Laboratories and the National Renewable Energy Laboratory (NREL), the RTC program partners with US manufacturers of photovoltaic (PV) technologies, including modules, inverters, and balance-of-system equipment. The study is collaborative, with manufacturers (also known as RTC industry partners) and the national labs working together on a system design and validation strategy that meets a clearly defined set of performance and reliability objectives.

14 SOLAR ENERGY↗
DOE OSTI2016

Numbering-Up of Microscale Devices for Megawatt-Scale Supercritical Carbon Dioxide Concentrating Solar Power Receivers

Concentrated solar power (CSP) plants have the potential to reduce the consumption of nonrenewable resources and greenhouse gas emissions in electricity production. In CSP systems, a field of heliostats focuses solar radiation on a central receiver, and energy is then transferred to a thermal power plant at high temperature. However, maximum receiver surface fluxes are low (30–100 W cm -2 ) with high thermal losses, which has contributed to the limited market penetration of CSP systems. Recently, small (~4 cm 2 ), laminated micro pin-fin devices have shown potential to achieve concentrated surface fluxes over 100 W cm -2 using supercritical CO 2 as the working fluid. The present study explores the feasibility of using these microscale unit cells as building blocks for a megawatt-scale (250 MW thermal) open solar receiver through a numbering-up approach, where multiple microscale unit cell devices are connected in parallel. A multiscale model of the full-scale central receiver is developed. The model consists of interconnected unit cell and module level (i.e., multiple unit cells in parallel) submodels which predict local performance of the central receiver. Each full-scale receiver consists of 3000 micro pin-fin unit cells divided into 250 modules. The performance of three different full-scale receivers is simulated under representative operating conditions. The results show that the microscale unit cells have the potential to be numbered up to megawatt applications while providing high heat flux and thermal efficiency. At the design incident flux and surface emissivity, a global receiver efficiency of approximately 90% when heating sCO 2 from 550 °C to 650 °C at an average incident flux of 110 W cm -2 can be achieved.

14 SOLAR ENERGY↗
DOE OSTI2021

PV in the circular economy, a dynamic framework analyzing technology evolution and reliability impacts

Rapid, terawatt-scale deployment of photovoltaic (PV) modules is required to decarbonize the energy sector. Despite efficiency and manufacturing improvements, material demand will increase, eventually resulting in waste as deployed modules reach end of life. Circular choices for decommissioned modules could reduce waste and offset virgin materials. We present PV ICE, an open-source python framework using modern reliability data, which tracks module material flows throughout PV life cycles. We provide dynamic baselines capturing PV module and material evolution. PV ICE includes multimodal end of life, circular pathways, and manufacturing losses. We present a validation of the framework and a sensitivity analysis. Results show that manufacturing efficiencies strongly affect material demand, representing >20% of the 9 million tons of waste cumulatively expected by 2050. Reliability and circular pathways represent the best opportunities to reduce waste by 56% while maintaining installed capacity. Shorter-lived modules generate 81% more waste and reduce 2050 capacity by 6%.

14 SOLAR ENERGY↗
DOE OSTI2019

Field-Aged Glass/Backsheet and Glass/Glass PV Modules: Encapsulant Degradation Comparison

Ethylene vinyl acetate (EVA) is the predominant encapsulant in crystalline-silicon photovoltaic (PV) modules; however, its degradation is a subject of major concern, which causes significant power loss under field conditions. This article presents a comparison of EVA degradation in field-aged PV modules with glass/backsheet (G/B) and glass/glass (G/G) architectures. Modulelevel characterization included UV fluorescence imaging and I-V measurements. Material analytical techniques, including colorimetry, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Raman spectroscopy, were performed to correlate the module performance parameters with EVA material properties. An intense EVA discoloration in G/G modules was observed, which was corroborated by higher module Isc and Pmax degradation rates compared with its counterpart G/B modules. Higher power degradation was accompanied by a significant increase in EVA crosslinking, vinyl acetate content, yellowness index, and presence of functional groups containing unsaturated moieties that are linked to degradation products of photothermal reaction, and a higher decrease in the degree of crystallinity. The absence of a polymeric backsheet in hermetically sealed G/G modules, which restricts photobleaching and enhances the entrapment of volatile acetic acid and other degradation by-products, plays a major role in causing higher EVA degradation in G/G modules. This article concludes that EVA might have been a good choice of an encapsulant for the G/B modules over the decades, but it may prove to be an inappropriate choice for the G/G modules because of potential degassing, corrosion, and/or discoloration issues. Ionomers or polyester-based encapsulants like polyolefins could be best suited for G/G modules as it appears to be a current trend in the industry.

14 SOLAR ENERGY↗
DOE OSTI2018

NREL's Cell and Module Performance Group's Asymptotic Pmax Protocol for Perovskite Devices

Perovskite photovoltaic devices have demonstrated a very rapid rise in reported efficiencies. Potentially extreme artifacts which tend to manifest themselves as large hysteresis effects, depending an scan rates and directions and light bias exposure history are often seen. This can make characterization difficult and may have resulted in some exaggerated efficiency reports. NREL's Cell and Module Performance (CMP) group's approach to standardized measurements of perovskites is discussed.

14 SOLAR ENERGY↗
DOE OSTI2015

U.S. Photovoltaic Prices and Cost Breakdowns. Q1 2015 Benchmarks for Residential, Commercial, and Utility-Scale Systems

The price of photovoltaic (PV) systems in the United States (i.e., the cost to the system owner) has continued to decline across all major market sectors. This report provides a Q1 2015 update regarding the prices of residential, commercial, and utility scale PV systems, based on an objective methodology that closely approximates the book value of a PV system. Several cases are benchmarked to represent common variations in business models, labor rates, and system architecture choice. We estimate a weighted-average cash purchase price of $3.09/W for residential scale rooftop systems, $2.15/W for commercial scale rooftop systems, $1.77/W for utility scale systems with fixed mounting structures, and $1.91/W for utility scale systems using single-axis trackers. All systems are modeled assuming standard-efficiency, polycrystalline-silicon PV modules, and further assume installation within the United States.

14 SOLAR ENERGY↗
DOE OSTI2017

Impinging Water Droplets on Inclined Glass Surfaces

Multiphase computational models and tests of falling water droplets on inclined glass surfaces were developed to investigate the physics of impingement and potential of these droplets to self-clean glass surfaces for photovoltaic modules and heliostats. A multiphase volume-of-fluid model was developed in ANSYS Fluent to simulate the impinging droplets. The simulations considered different droplet sizes (1 mm and 3 mm), tilt angles (0°, 10°, and 45°), droplet velocities (1 m/s and 3 m/s), and wetting characteristics (wetting=47° contact angle and non-wetting = 93° contact angle). Results showed that the spread factor (maximum droplet diameter during impact divided by the initial droplet diameter) decreased with increasing inclination angle due to the reduced normal force on the surface. The hydrophilic surface yielded greater spread factors than the hydrophobic surface in all cases. With regard to impact forces, the greater surface tilt angles yielded lower normal forces, but higher shear forces. Experiments showed that the experimentally observed spread factor (maximum droplet diameter during impact divided by the initial droplet diameter) was significantly larger than the simulated spread factor. Observed spread factors were on the order of 5 - 6 for droplet velocities of ~3 m/s, whereas the simulated spread factors were on the order of 2. Droplets were observed to be mobile following impact only for the cases with 45° tilt angle, which matched the simulations. An interesting phenomenon that was observed was that shortly after being released from the nozzle, the water droplet oscillated (like a trampoline) due to the "snapback" caused by the surface tension of the water droplet being released from the nozzle. This oscillation impacted the velocity immediately after the release. Future work should evaluate the impact of parameters such as tilt angle and surface wettability on the impact of particle/soiling uptake and removal to investigate ways that photovoltaic modules and heliostats can be designed to maximize self-cleaning.

14 SOLAR ENERGY↗
DOE OSTI2020

PV High Wind User Test Facility

The creation of a PV high wind test facility at the NREL Flatirons Campus that will enable private and public research efforts aimed at storm hardening PV systems. The facility will be instrumented to monitor effects of high wind conditions on modules and other array components. These in-field tests will coordinate with flow models, wind tunnel testing, validation of PV aeroelastic design codes, and post-testing module and system component analysis.

14 SOLAR ENERGY↗
DOE OSTI2023

Analyzing Terawatt Scale Sustainability with PV ICE Tool

Renewable energy reduces environmental impacts and decarbonizes the production of other goods. But, manufacturing renewable energy sources, such as photovoltaic (PV) modules, require energy inputs that are currently carbon intensive. So, how do we decarbonize and circularize these critical technologies to achieve a sustainable energy transition? As we manufacture and deploy solar PV at a fast pace to support the Energy Transition, this talk will cover some of the most relevant metrics for evaluating the success of our circular economy and sustainability choices.

circular economy↗
DOE OSTI2019

Rapid Aqueous Spray Fabrication of Robust NiO x : A Simple and Scalable Platform for Efficient Perovskite Solar Cells

Organometal halide perovskites have powerful intrinsic potential to drive next-generation solar technology, but their insufficient thermomechanical reliability and unproven large-area manufacturability limit competition with incumbent silicon photovoltaics. This work addresses these limitations by leveraging large-area processing and robust inorganic hole transport layers (HTLs). Inverted perovskite solar cells utilizing NiO x HTLs deposited by rapid aqueous spray-coating that outperform spin-coated NiO x and lead to a 5× improvement in the fracture energy (Gc), a primary metric of thermomechanical stability, are presented. Additionally, the morphology, chemical composition, and optoelectronic properties of the NiO x films are characterized to understand and optimize compatibility with an archetypal double cation perovskite, Cs .17 FA .83 Pb(Br .17 I .83 ) 3 . Perovskite solar cells with sprayed NiO x show higher photovoltaic performance, exhibiting up to 82% fill factor and 17.7% power conversion efficiency (PCE)—the highest PCE reported for inverted cell with scalable charge transport layers—as well as excellent stability under full illumination and after 4000 h aging in inert conditions at room temperature. By utilizing open-air techniques and aqueous precursors, this combination of robust materials and low-cost processing provides a platform for scaling perovskite modules with long-term reliability.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Large-Area Material and Junction Damage in c-Si Solar Cells by Potential-Induced Degradation

A new potential-induced degradation (PID) mechanism for c-Si is reported. Multiple characterization techniques in various aspects of a material's chemical, structural, electrical, and optoelectrical nature, as well as in atomic, nanometer, micrometer, millimeter, and cell and module scales, are combined. All results point consistently to a new discovery: substantial large-area deterioration of materials and junctions plays a major role.

14 SOLAR ENERGY↗
DOE OSTI2017

Comparison of Pyranometers and Reference Cells on Fixed and One-axis Tracking Surfaces

Photovoltaic (PV) system perfomance is monitored by a wide variety of sensors. These instruments range from secondary standard pyranometers to photodiode-based pyranometers to reference cells. Although instruments are mounted in the plane of array of the modules a wide range of results have been obtained. Some of these difference have been assumed to come from systematic uncertainties associated with the irradiance sensors. This study is an attempt to quantify these differences by comparing the output of selected thermopile-based pyranometers to photodiode-based pyranometers and reference cells on a horizontal surface, a fixed-tilt surface, and a one-axis tracking surface. This analysis focuses on clear-sky results from two sites with different climatic conditions. Several important features were observed. Photodiode-based pyranometers and reference cells produce widely different results under clear skies, especially at larger angles-of-incidence even though both instruments are based on measuring the short circuit current of solar cells. The difference is caused by the scattering of light as it passes through the glazing of the reference cell or the diffuser lens of the photodioded- base pyranometer. Both instruments are shown to have similar response to the spectral distribution of the irradiance when compared to the thermopile-based pyranometer that has a response nearly independent of the wavelength of light used by PV modules.

14 SOLAR ENERGY↗
DOE OSTI2024

Tracking the Sun: Pricing and Design Trends for Distributed Photovoltaic Systems in the United States, 2024 Edition [Slides]

Berkeley Lab’s annual Tracking the Sun report describes trends among grid-connected, distributed solar photovoltaic (PV) and paired PV+storage systems in the United States. For the purpose of this report, distributed solar includes residential systems, roof-mounted non-residential systems, and ground-mounted systems up to 5 MW-AC. Ground-mounted systems larger than 5 MW-AC are covered in Berkeley Lab’s companion annual report, Utility-Scale Solar. The latest edition of the report is based on 3.7 million systems installed through year-end 2023, representing close to 80% of systems installed to date. The report describes and discusses key trends related to: -Project characteristics, including system size, module efficiencies, roof-coverage ratios, prevalence of paired PV with storage, use of module-level power electronics, third-party ownership, mounting configurations, panel orientation, and customer segmentation -Median installed-price trends, both nationally and by state -Variability in pricing according to system size, state, installer, equipment type, and other factors, relying on both descriptive analysis and a multi-variate regression to estimate the effects of key pricing drivers for residential systems installed in 2023.

14 SOLAR ENERGY↗
DOE OSTI2021

New Modulation and Impact of Transformer Leakage Inductance on Current-Source Solid-State Transformer

This article presents a novel modulation scheme for device voltage stress mitigation and comprehensive analysis of the impact of transformer leakage inductance in a current-source solid-state transformer (SST). Different from dual active bridge (DAB) SST, the operation of the current-source SST is similar to that of a flyback converter. The device bridge on only one side of the transformer is active to store energy into or release energy from the magnetizing inductance which acts as a current-source dc link. Such flyback operation with reverse-blocking switches can lead to additional device voltage stress and incomplete zero-voltage switching (ZVS) on the current-source soft-switching solid-state transformer (S4T) under conventional modulation. A new modulation scheme is proposed to address this issue. Moreover, different from the DAB, the leakage inductance of the medium-frequency transformer (MFT) in the S4T is a parasitic element similar to that in a matrix SST and can cause additional device voltage stress. Though the resonant capacitors, originally added to achieve ZVS, can absorb and recycle the leakage energy in the S4T, these capacitors need to be increased with larger leakage inductances to limit the voltage stress. However, large resonant capacitors can result in more lost duty cycles and reduced efficiency. The impact of such leakage inductance on device voltage stress is analyzed comprehensively, which is critical to guide future research and design of the S4T. Experimental results from S4T prototypes for DC-DC, multiport AC-DC, and AC-AC conversion with 1:1 and 4:1 MFT comprehensively verify the proposed concepts. Lastly, a case study of a three-phase AC-AC S4T over a power range from 1 kVA to 100 kVA each module reveals that the MFT leakage inductance should be less than 1% of the magnetizing inductance for safe operation.

14 SOLAR ENERGY↗