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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 595 records · Page 33

Mechanistic studies of photothermal aging

Cracks were observed forming in Tedlar back cover films on PV modules mounted outdoors in the natural environment. The cracks appear to approximate reasonable straight lines and, in general, are parallel to each other. It is implied that the directionality of these cracks may be in some way related to film orientation. Preliminary results from the Jet Propulsion Laboratory (JPL) studies investigating the causes of these cracks indicate that Tedlar does not become brittle on aging. It was speculated that perhaps compounding ingredients employed in EVA may migrate into the Tedlar film, thus causing a potential for chemical effects.

Liang, R. H.↗

Encapsulant free-surfaces and interfaces: Critical parameters in controlling cell corrosion

Results are reported of studying the interaction of moisture with photovoltaic (PV) modules and custom-built test coupons in both laboratory and outdoor ambient environments. Characteristics measured included module cell-to-frame leakage currents, encapsulant bulk and surface currents, glass surface currents, and encapsulant/glass interface currents as functions of temperature and humidity. Using a computer model of interelectrode conduction, preferential conduction paths in PVB- and EVA-encapsulated modules are identified. In comparing the results of field and laboratory test environments on identical samples, comments are made about the greater severity of the outdoor environment. Several aspects of water-module interaction, including design strategies and continuing research, are discussed.

Mon, G.↗

STS-97 ISS Science Payloads Briefing

John Un, International Space Station (ISS) Lead Increment Scientist, gives an overview of the STS-97 Endeavour mission payload (PV Module P6) and Expedition 1 crew. He describes the research and experimentation to take place on the ISS in the following fields: (1) Life Sciences, (2) Microgravity Research, (3) Commercial, (4) Space Sciences, and (5) Earth Sciences. Observations of Earth include images of the Aral Sea in central Asia and fires in Mongolia. Mr. Un then answers questions from the press.

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STS-97 Post Flight Presentation

Various shots highlight the STS-97 Endeavour mission. Footage shows the crew suiting up and leaving the Operations and Checkout (O&C) Building, the launch, and landing. Various on-orbit activities are seen, such as docking with the International Space Station (ISS), the spacewalks (installing the PV Module P6), array deployment, meeting the Expedition 1 crew, eating, and undocking. Shots show the northern lights and a meteorite entering Earth's atmosphere from above. The Andes can be seen from the Orbiter while the P6 arrays are deploying.

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Solar Electric System

Heat Pipe Technology, Inc. undertook the development of a PV system that could bring solar electricity to the individual home at reasonable cost. His system employs high efficiency PV modules plus a set of polished reflectors that concentrate the solar energy and enhance the output of the modules. Dinh incorporated a sun tracking system derived from space tracking technology. It automatically follows the sun throughout the day and turns the modules so that they get maximum exposure to the solar radiation, further enhancing the system efficiency.

Source record↗

Space and Terrestrial Photovoltaics: Synergy and Diversity

A historical view of the research and development in photovoltaics from the perspective of both the terrestrial and the space communities is presented from the early days through the '70s and '80s and the '90s and beyond. The synergy of both communities in the beginning and once again in the present and hopefully future are highlighted, with examples of the important features in each program. The space community which was impressed by the light-weight and reliability of photovoltaics drove much of the early development. Even up to today, nearly every satellites and other scientific space probe that has been launched has included some solar power. However, since the cost of these power systems were only a small fraction of the satellite and launch cost, the use of much of this technology for the terrestrial marketplace was not feasible. It was clear that the focus of the terrestrial community would be best served by reducing costs. This would include addressing a variety of manufacturing issues and raising the rate of production. Success in these programs and a resulting globalization of effort resulted in major strides in the reduction of PV module costs and increased production. Although, the space community derived benefit from some of these advancements, its focus was on pushing the envelope with regard to cell efficiency. The gap between theoretical efficiencies and experimental efficiencies for silicon, gallium arsenide and indium phosphide became almost non-existent. Recent work by both communities have focused on the development thin film cells of amorphous silicon, CuInSe2 and CdTe. These cells hold the promise of lower costs for the terrestrial community as well as possible flexible substrates, better radiation resistance, and higher specific power for the space community. It is predicted that future trends in both communities will be directed toward advances through the application of nanotechnology. A picture is emerging in which the space and terrestrial solar cell communities shall once again share many common goals and, in fact, companies may manufacture both space and terrestrial solar cells in III-V materials and thin film materials. Basic photovoltaics research including these current trends in nanotechnology provides a valuable service for both worlds in that fundamental understanding of cell processes is still vitally important, particularly with new materials or new cell structures. It is entirely possible that one day we might have one solar array design that will meet the criteria for success in both space and on the Earth or perhaps the Moon or Mars.

Bailey, Sheila↗

Space Station Power Generation in Support of the Beta Gimbal Anomaly Resolution

The International Space Station (ISS) is the largest and most complex spacecraft ever assembled and operated in orbit. The first U.S. photovoltaic (PV) module, containing two solar arrays, was launched, installed, and activated in early December 2000. After the first week of continuously rotating the U.S. solar arrays, engineering personnel in the ISS Mission Evaluation Room (MER) observed higher than expected electrical currents on the drive motor in one of the Beta Gimbal Assemblies (BGA), the mechanism used to maneuver a U.S. solar array. The magnitude of the motor currents continued to increase over time on both BGA's, creating concerns about the ability of the gimbals to continue pointing the solar arrays towards the sun, a function critical for continued assembly of the ISS. A number of engineering disciplines convened in May 2001 to address this on-orbit hardware anomaly. This paper reviews the ISS electrical power system (EPS) analyses performed to develop viable operational workarounds that would minimize BGA use while maintaining sufficient solar array power to continue assembly of the ISS. Additionally, EPS analyses performed in support of on-orbit BGA troubleshooting exercises is reviewed. EPS capability analyses were performed using SPACE, a computer code developed by NASA Glenn Research Center (GRC) for the ISS program office.

Delleur, Ann M.↗

Progress & Frontiers in PV Performance

PowerPoint slides for a presentation given at Solar Power International 2016. Presentation includes System Advisor Model (SAM) introduction and battery modeling, bifacial PV modules and modeling, shade modeling and module level power electronics (MLPE), degradation rates, and PVWatts updates and validation.

14 SOLAR ENERGY↗

Bifacial PV System Performance: Separating Fact from Fiction

The performance of bifacial PV systems depends greatly on the installed conditions. Previous simulations and results have shown very high bifacial gain improvement, but this may not be the case for all conditions, particularly for large-scale systems with self-shading, lower-cost PV modules (PERC) which might have lower bifaciality coefficient, and field deployments over natural ground cover. But not to worry! Financial models indicate that even with these lower performance conditions, and with bifacial gain of 4%-9%, bifacial modules can still provide improved LCOE.

14 SOLAR ENERGY↗

Suggested Modifications for Bifacial Capacity Testing: Preprint

Capacity tests such as those described in ASTM 2848 and IEC 61724-2 are widely used during the contracting and acceptance testing of PV systems. With the increasing deployment of bifacial PV modules, there is a need to develop a standardized approach to capacity test these systems. Although variability and bias error was inherently higher for the measured capacity of bifacial systems, it could be reduced to a level consistent with the monofacial reference system by appropriate incorporation of rear irradiance- either measured or modeled. Three field installations provided bifacial system capacity that was measured with a mean bias error and standard deviation within 1% over the 2-10 month observation period. Capacity test accuracy could be improved further by utilizing measured back-of-module temperature and the IEC 61724-2 test method.

14 SOLAR ENERGY↗

Cyberguardians Webinar

Robust solar industry growth is creating a shortage of U.S. workers who are knowledgeable in emerging Distributed Energy Resource (DER) technologies including networking, operational software, smart advanced inverters, smart advanced PV modules, and cybersecurity. Retraining military veterans and other qualified individuals to fill workforce gaps in those technologies is the project focus. The project leverages the experience and contributions of DER and cybersecurity experts, educational organizations offering accreditation, and groups serving our nation’s veterans to meet its goals. To bridge this workforce skills gap, the Cyberguardians and STEM Warriors project will establish a complete learning and career advancement system for veterans, transitioning military personnel and other qualified individuals into the DER workforce. The project will guide participants successfully through the process of program/vocation selection, curriculum enrollment, academic mentoring, degree or certificate attainment, job board enrollment, introduction to hiring managers at DER companies, and successful job acquisition. This webinar was used to promote the Cyberguardians program and to ensure ample news coverage to reach veterans, employers, and others that would benefit from this program.

14 SOLAR ENERGY↗

More Than Recycling: How Should We Define Circularity Goals for PV in a Global Energy Transition? Preprint

Energy transition to carbon-free electricity is a crucial pillar of the Circular Economy. 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? This work proposes that effective capacity-the installed capacity accounting for degradation rates and failures-is a critical metric to evaluate renewable energy technologies on the path toward circular economy and energy transitions. Our analyses also emphasize the importance of examining a suite of metrics incorporating mass and energy flows to identify potential tradeoffs and inform design or lifecycle management decisions holistically.

bifacial↗

Evaluation of Surface Crack Formation in Photovoltaic Backsheets Using Fragmentation and Finite Element Simulations: Preprint

Backsheet cracking is among the most commonly observed degradation modes of photovoltaic (PV) modules in the field. Cracks can reduce the ability of backsheets to fulfil their functions, for example, protection of the modules from the environment or electrical insulation. This work presents an evaluation of the degradation and cracking propensity of two backsheets during accelerated IEC TS 62788-7-2 A3 (International Electrotechnical Commission) aging with the fragmentation test: a co-extruded polyamide backsheet (AAA), and a laminated multilayer backsheet with a polyethylene terephthalate core and outer layer and ethylene vinyl acetate inner layer (PPE). Results show the surface embrittlement of the AAA outer layer during exposure. A longer time of exposure causes cracks to form at lower strains during stretching and creates deeper cracks. Accordingly, Young's modulus of the outer layer increases, as measured by cross-sectional nanoindentation. PPE exhibits cracking after exposure as well. While no similar increase of modulus or crack depth can be observed, the outer layer of PPE exhibits more obvious signs of erosion during exposure, including progressive morphological changes and thickness losses. A finite element model to simulate surface crack formation is devised, based on initially zero-thickness decohesion elements. Decohesion criteria define a critical stress, at which these elements grow, and cracks can begin to form. These criteria are obtained via parameter optimization by comparison between simulation and experiment. The model is used to interpret crack formation in both backsheets.

backsheet↗

More Than Recycling: The Importance of Multiple Metrics for a Circular Economy for PV in the Energy Transition

Energy transition to carbon-free electricity is a crucial pillar of the Circular Economy. 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? This work proposes that effective capacity-the installed capacity accounting for degradation rates and failures-is a critical metric to evaluate renewable energy technologies on the path toward circular economy and energy transitions. Our analyses also emphasize the importance of examining a suite of metrics incorporating mass and energy flows to identify potential tradeoffs and inform design or lifecycle management decisions holistically.

bifacial↗

A Generic and Multi-Functional Electromagnetic Transient Model for Grid-Following Inverter: Preprint

This article presents a generic and multi-functional electromagnetic transient (EMT) dynamic model of grid following (GFL) inverter-based resource (IBR) using the PSCAD TM software platform. The features of the developed model includes the flexibility in selecting various types and combinations of DC sources covering PV modules, battery modules, ideal DC source module, as well as flexibility in selecting either switched or averaged model of inverter. This model also covers exhaustive lists of controller logic covering open-loop/closed-loop PQ dispatch control, DC voltage and AC terminal voltage control along with the conventional current control designed in dq-domain, aB- domain and positive-negative sequence domain. Moreover, this model is equipped with the flexibility in selecting various types of current limiting schemes that includes saturation-based as well as latching-based current limiter, anti-windup protection. Moreover, the EMT model is agnostic to the MVA rating and is suitable for interfacing transmission systems by being complaint with the IEEE Std. 2800. The generality in the power circuits and the multi-functional options in operation and control of the developed EMT model makes it suitable for both academia and industry to study various power system aspects not limited to but such as fault behavior of GFL IBR and impacts on protection system, transient stability of a system interfaced with large number of GFL IBRs etc.

grid following inverter↗

Combined-Accelerated Stress Testing of Photovoltaic Materials

By applying multiple environmental stresses in fieldrepresentative combinations and sequences, combined-accelerated stress testing (CAST) identifies degradation modes and failure mechanisms of photovoltaic (PV) modules and components that are missed by single stress factor accelerated testing.

14 SOLAR ENERGY↗

Development of Manufacturing Technology to Accelerate Cost Reduction of Low Concentration and

The purpose of this project was to accelerate deployment of cost-effective US-based manufacturing of Solaria’s unique c-Si module technology. This effort successfully resulted in the development of US-based manufacturing technology to support two highly-differentiated, market leading product platforms. The project was initially predicated on developing Solaria’s low-concentration PV (LCPV) module technology which at the time of the award was uniquely positioned to exceed the SunShot price goal of $0.50/Wp for standard c-Si modules. The Solaria LCPV module is a 2.5x concentrator that leverages proven, high-reliability PV module materials and low silicon cell usage into a technology package that already had the lowest direct material cost and leading Levelized Cost of Electricity (LCOE). With over 25 MW commercially deployed globally, the Solaria module was well positioned to continue to lead in PV module cost reduction. Throughout the term of the contract, market conditions changed dramatically and so to did Solaria’s product offerings to support this. However, the manufacturing technology developed for the LCPV module was successfully leveraged and optimized to support two new and different product platforms. BIPV “PowerVision” and High-efficiency “PowerXT” modules. The primary barrier to enabling high-volume PV module manufacturing in the US is the high manual labor component in certain unique aspects of our manufacturing process. The funding was used to develop unique manufacturing automation which makes the manual labor components of these key processes more efficient and increase throughput. At the core of Solaria’s product offerings are its unique and proprietary techniques for dicing and re-arranging solar cells into modules with highly-differentiated characteristics that address key gaps in the c-Si market. It is these techniques that were successfully evolved and deployed into US-based manufacturing site with SunShot funding. Today, Solaria is currently positioned to become the market leader with these two technologies over the coming 24 months largely due to the successful innovations of the underlying manufacturing technology. This success will leverage US-based manufacturing technology and the associated US-jobs to support. Solaria views the project as highly successful and a great example of SunShot funding enabling the creating of US jobs and the deployment of ubiquitous solar energy products.

14 SOLAR ENERGY↗