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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Antisoiling Coatings for Solar-Energy Devices

Fluorocarbons resist formation of adherent deposits. Promising coating materials reduce soiling of solar photovoltaic modules and possibly solar thermal collectors. Contaminating layers of various degrees of adherence form on surfaces of devices, partially blocking incident solar energy, reducing output power. Loose soil deposits during dry periods but washed off by rain. New coatings help prevent formation of more-adherent, chemically and physically bonded layers rain alone cannot wash away.

Cuddihy, E. F.↗
NASA NTRS1985

Encapsulant selection and durability testing experience

The Flat Plate Solar Array Project (FSA) has established technically challenging cost and service life goals for photovoltaic modules. These goals are a cost of $70 sq m and an expected 30 years of service life in an outdoor weathering environment. out of the cost goal, $14 sq m is allocated for encapsulation materials, which includes the cost of a structural panel. At FSA's inception in 1975, the cumulative cost of encapsulation materials in popular use, such as room temperature vulcanized (RTV) silicones, aluminum panels, etc., greatly exceeded $14/sq m. Accordingly, it became necessary to identify and/or develop new materials and new material technologies to achieve the goals. Many of these new materials are low cost polymers that satisfy module engineering and encapsulation processing requirements but unfortunately are not intrinsically weather stable. This necessitates identifying lifetime and/or weathering deficiencies inherent in these low cost materials and developing specific approaches to enhancing weather stability.

Cuddihy, E. F.↗
NASA NTRS1985

Electrical research on solar cells and photovoltaic materials

A systematic study of the properties of various polymer pottant materials and of the electrochemical corrosion mechanisms in solar cell materials is required for advancing the technology of terrestrial photovoltaic modules. The items of specific concern in this sponsored research activity involve: (1) kinetics of plasticizer loss in PVB, (2) kinetics of water absorption and desorption in PVB, (3) kinetics of water absorption and desorption in EVA, (4) the electrical properties at PVB as a function of temperature and humidity, (5) the electrical properties of EVA as a function of temperature and humidity, (6) solar cell corrosion characteristics, (7) water absorption effects in PVB and EVA, and (8) ion implantation and radiation effects in PVB and EVA.

Orehotsky, J.↗
NASA NTRS1986

Chemical bonding technology

Primers employed in bonding together the various material interfaces in a photovoltaic module are being developed. The approach develops interfacial adhesion by generating actual chemical bonds between the various materials bonded together. The current status of the program is described along with the progress toward developing two general purpose primers for ethylene vinyl acetate (EVA), one for glass and metals, and another for plastic films.

Plueddemann, E.↗
NASA NTRS1986

Water permeation and electrical properties of pottants, backings, and pottant/backing composites

It is reported that the interface between plastic film back covers and ethylene vinyl acetates (EVA) or polyvinyl butyral (PVB) in photovoltaic modules can influence water permeation, and electrial properties of the composites such as leakage current and dielectric constant. The interface can either be one of two dissimilar materials in physical contact with no intermixing, or the interface can constitute a thin zone which is an interphase of the two materials having a gradient composition from one material to the other. The former condition is described as a discrete interface. A discrete interface model was developed to predict water permeation, dielectric strength, and leakage current for EVA, ethylene methyl acrylate (EMA), and PVB coupled to Tedlar and mylar films. Experimental data was compared with predicted data.

Orehotsky, J.↗
NASA NTRS1990

Orientation of Space Station Freedom electrical power system in environmental effects assessment

The orientation effects of six Space Station Freedom Electrical Power System (EPS) components are evaluated for three environmental interactions: aerodynamic drag, atomic oxygen erosion, and orbital debris impact. Designers can directly apply these orientation factors to estimate the magnitude of the examined environment and the environmental effects for the EPS component of interest. The six EPS components are the solar array, photovoltaic module radiator, integrated equipment assembly, solar dynamic concentrator, solar dynamic radiator, and beta gimbal.

Lu, Cheng-Yi↗
NASA NTRS1992

Results of thermal vacuum tests for the PASP Plus flight panels

The PASP+ experiment is collection of 16 individual cell strings on 12 different photovoltaic modules, representing a wide variety of cell and array technologies, which will be launched from a Pegasus in early 1993. The main objectives of the experiment are to obtain environmental interaction data between the modules and the space plasma; and to obtain radiation damage data on the newer types of cells. The orbit will be about 1050 nautical miles by 190 nautical miles with an inclination of 70 degrees. During late June and early July of this year, we took the PASP+ panels with all 12 modules and the flight controller to Boeing for a series of thermal vacuum tests. The main objectives of these tests were to verify the thermal balance model of the space experiment; to obtain good data for temperature coefficients of the various modules; and to have an 'end-to-end' test of the modules and controller. We will present data on the module temperatures and the measured temperature coefficients. We shall discuss the limitations of the test setup and some of the assumptions that were made. We shall also present some module performance as a function of temperature.

Guidice, Don↗
NASA NTRS2004

Reconditioning of Batteries on the International Space Station

Primary source of electric power for the International Space Station (ISS) is the photovoltaic module (PVM). At assembly complete stage, the ISS will be served by 4 PVMs. Each PVM contains two independent power channels such that one failure will result in loss of only one power channel. During early stages of assembly, the ISS is served by only one PVM designated as P6. Solar arrays are used to convert solar flux into electrical power. Nickel hydrogen batteries are used to store electrical power for use during periods when the solar input is not adequate to support channel loads. Batteries are operated per established procedures that ensure that they are maintained within specified temperature limits, charge current is controlled to conform to a specified charge profile, and battery voltages are maintained within specified limits. Both power channels on the PVM P6 have been operating flawlessly since December 2000 with 100 percent power availability. All components, including batteries, are monitored regularly to ensure that they are operating within specified limits and to trend their wear out and age effects. The paper briefly describes the battery trend data. Batteries have started to show some effects of aging and a battery reconditioning procedure is being evaluated at this time. Reconditioning is expected to reduce cell voltage divergence and provide data that can be used to update the state of charge (SOC) computation in the software to account for battery age. During reconditioning, each battery, one at a time, will be discharged per a specified procedure and then returned to a full state of charge. The paper describes the reconditioning procedure and the expected benefits. The reconditioning procedures have been thoroughly coordinated by all affected technical teams and approved by all required boards. The reconditioning is tentatively scheduled for September 2004.

Hajela, Gyan↗
NASA NTRS2004

Space Station Power Generation Investigated 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 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 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 (see the on-orbit photograph). The magnitude of the motor currents continued to increase over time on both BGAs, 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. The BGA provides two critical capabilities to the ISS: (1) transfer of electrical power across a rotating joint and (2) positioning of the solar arrays. A number of engineering disciplines convened in May 2001 to address this on-orbit hardware anomaly. Over the course of a year, many scenarios were developed and used. Only two are discussed here: parked arrays and dual-angle mode.

Delleur, Ann M.↗
DOE OSTI2020

Methods and systems for determining soiling on photovoltaic devices

An aspect of the present disclosure relates to radiating light on to a front surface of a glass pane comprising a first surface and a second surface defining a thickness between the first surface and the second surface, wherein the first surface is substantially parallel to the second surface; detecting a transmittance of the light through the glass pane; comparing the transmittance through the glass pane to a reference transmittance value corresponding to a clean reference glass pane; and determining, using the transmittance and the reference transmittance, a soiling metric of a photovoltaic module.

14 SOLAR ENERGY↗
DOE OSTI2022

Spatiotemporal Modeling of Real World Backsheets Field Survey Data: Hierarchical (Multilevel) Generalized Additive Models: Preprint

Assessing photovoltaic module backsheet durability is critical to increasing module lifetime. Lab based accelerating testing has recently failed to predict large scale failures of widely adopted polymeric materials. Field surveyed data is critical to assess the performance of component lifetime. Using a documented field survey protocol, 13 field surveys where conducted. Each measurement is encoded with it's spatial location in respect to the other modules. By combining field survey data on degradation predictors with real time satellite weather data, data-driven predictive models of backsheet degradation were trained. LOESS models were constructed to investigate the spatial dependence of measurements. It was found that micro-climatic effects like treelines, ground surface changes, and elevation changes effected the magnitude and variance of the measurements. A GAM model was created to predict the value of degradation based on measured predictors. The model includes variables on the climate of the system and the location of each measurement in the PV mounting structure. The model performed well with an adj:R2 of 0:95 for yellowness index prediction. The model was cross-validated using k-folds.

backsheet↗
DOE OSTI2023

Tunable negative coefficient thermal expansion materials and composites

The present disclosure is directed to variable composition ceramics. Zr (2−x) Hf (x) WP 2 O 12 and Hf 2 WP 2 O 12 exhibit large negative thermal expansion that is linear over a large temperature range up to at least 900° C., These new ceramic material particles may be mixed with polymers to make a composite suitable for use in backsheets for photovoltaic modules or in other applications. The thermal expansion coefficient of the composite can be tailored to match that of the solar cell in order to reduce stress resulting from daily thermal cycling.

Gordon, Margaret Ellen↗
DOE OSTI2026

Robotics for Energy Infrastructure Construction on Earth and Beyond: Pilot Study Exploring Level 3-4 Semi-Autonomous Installation of a Reduced-Scale Photovoltaic Power Plant Prototype: Preprint

There is a growing need to build energy infrastructure at massive scale on both Earth and in space. On Earth, increasing electricity demand from applications such as AI data centers is driving rapid expansion of power systems, while in space, long-duration missions such as lunar operations require reliable and resilient energy infrastructure that can be deployed quickly. These needs outpace the capabilities of conventional construction methods. Robotic construction offers a path to faster, lower-cost, and more consistent deployment, yet most existing approaches focus on automating individual tasks rather than end-to-end assembly. The Industrialized Construction Innovation (ICI) team at the National Laboratory of the Rockies (NLR), in collaboration with the Colorado School of Mines, has been investigating robotics and automation strategies for rapid end-to-end energy infrastructure construction. This paper presents a pilot study demonstrating level 3-4 semi-autonomous, end-to-end robotic assembly of a reduced-scale photovoltaic power plant prototype under terrestrial conditions. The approach combines hardware redesign of photovoltaic components for robotic compatibility, discrete-event and physics-based robotic simulations in synthetic environments, and sim-to-real deployment to execute end-to-end robotic assembly of[NM1.1][NM1.2] tracking components, structural members, photovoltaic modules, and embedded electrical connections. The pilot identifies key limitations like tolerance management, perception and localization, end effector capability, fastening methods, and multi-physics simulation fidelity, that must be addressed to enable end-to-end robotic assembly of full-scale energy infrastructure. The study highlights how these insights inform scaling strategies for terrestrial energy infrastructure and adaptation to unstructured and extreme environments, including off-world scenarios such as robotic assembly of vertical tall lunar towers.

14 SOLAR ENERGY↗
DOE OSTI2020

Detection and Localization of Damaged Photovoltaic Cells and Modules Using Spread Spectrum Time Domain Reflectometry

The operating efficiency of photovoltaic (PV) plants can be improved if damaged or degraded modules can be detected and identified. Currently, string-level power electronics can detect problems with modules or cabling but not locate them, which would facilitate addressing these issues. Here, we investigate the ability of spread spectrum time domain reflectometry (SSTDR) to both detect and locate/identify damaged cells and modules within a series-connected PV string. We tested the ability of SSTDR to detect and locate single-cell mini-modules and full-sized PV modules, which were intentionally damaged by impacts with a hammer (breaking the glass and damaging the silicon below) or by cutting through some or all busbars. Damage to the glass and silicon of cells was detected and located within a small string of minimodules. Busbar damage was detectable only if an open was created by cutting through all intercell busbars. Furthermore, physical impact damage to the glass and silicon of a full-sized PV module could be detected, but further development of signal processing is needed to achieve localization of such damaged modules within a string.

14 SOLAR ENERGY↗
DOE OSTI2025

Photovoltaic Mini-Module Soiling Stations: Cooperative Research and Development (Final Report)

Photovoltaic (PV) panels can become soiled due to a variety of environmental factors. This soiling reduces the amount of light reaching the cells and thus their energy output. The ratio of actual output of the soiled device that of a clean device is known as the soiling ratio. The daily change in soiling ratio is known as the soiling rate. To study soiling for different glass coatings. Two soiling stations were fabricated. The stations were designed to monitor the short-circuit current of PV cells encapsulated with glass featuring different coatings and measure the daily soiling ratio with a pair of reference cells, one of which is automatically brushed daily. This work meets the need to understand how the glass coatings perform in additional environments. The stations are designed to quantify both the soiling ratio (the ratio between actual/expected photovoltaic panel power output) as well as differences in anti-soiling performance of different glass coatings. The design of the dirty/clean reference cell system is described by Toth et al. The soiling ratio is calculated by calculating the average irradiance measured within one hour of solar noon by each of the reference cells and then taking the ratio of these daily near-noon averages. The soiling ratio time series for the station deployed in Georgia is shown in Figure 1. This figure shows that the soiling ratio at the site has not yet fallen below 0.99, indicating that peak daily soiling losses have been below 1%. The site was chosen because it is thought to be affected by pollen soiling. With continued monitoring over the course of at least a full year, we expect to be able to observe and quantify pollen soiling events.

14 SOLAR ENERGY↗
DOE OSTI2020

Combined Spatially Resolved Characterization of Antireflection and Antisoiling Coatings for PV Module Glass

Characterization of photovoltaic (PV) module materials throughout different stages of service life is crucial to understanding and improving the durability of these materials. Currently the large-scale of PV modules (>1 m 2 ) is imbalanced with the small-scale of most materials characterization tools (= 1 cm 2 ). Furthermore, understanding degradation mechanisms often requires a combination of multiple characterization techniques. Here, we present adaptations of three standard materials characterization techniques to enable mapping characterization over moderate sample areas (=25 cm 2 ). Contact angle, ellipsometry, and UV-Vis spectroscopy are each adapted and demonstrated on two representative samples: a commercial multi-functional coating for PV glass and an oxide combinatorial sample library. Best practices are discussed for adapting characterization techniques for large area mapping and combining mapping information from multiple techniques.

14 SOLAR ENERGY↗