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Results for “Photovoltaic Module”

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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
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 OSTI2019

Moldable photovoltaic solar cell module

A method is provided for making a molded photovoltaic module. The module includes a flexible polymeric flex-circuit substrate having an electrically conductive printed wiring pattern and solder pads defined on it. Small photovoltaic cells are affixed to the flex-circuit substrate by back-surface contacts in electrical contact with the solder pads. At least one thermoformable polymeric film is joined to the flex-circuit substrate. Each said solder pad comprises a solder composition that, after an initial melt, has a melting point that lies above at least a portion of the temperature range for thermoforming the polymeric film.

Nelson, Jeffrey S.↗
DOE OSTI2017

Design of photovoltaics for modules with 50% efficiency

Abstract We describe a spectrum splitting solar module design approach using ensembles of 2–20 subcells with bandgaps optimized for the AM 1.5D spectrum. Device physics calculations and experimental data determine radiative efficiency parameters for III ‐V compound semiconductor subcells and enable modification of conventional detailed balance calculations to predict module efficiency while retaining computational speed for a wide search of the design space. Accounting for nonideal absorption and recombination rates due to realistic material imperfections allows us to identify the minimum subcell quantity, quality, electrical connection configuration, and concentration required for 50% module efficiency with realistic optical losses and modeled contact resistance losses. We predict a module efficiency of 50% or greater will be possible with 7–10 electrically independent subcells in a spectral splitting optic at 300–500 suns concentration, assuming a 90% optical efficiency and 98% electrical efficiency, provided the subcells can achieve an average external radiative efficiency of 3–5% and a short circuit current that is at least 90% of the ideal. In examining spectrum splitting solar cells with both series‐connected and electrically independent subcells, we identify a new design trade‐off independent of the challenges of fabricating optimal bandgap combinations. Series‐connected ensembles, having a single set of electrical contacts, are less sensitive to lumped series resistance losses than ensembles where each subcells are contacted independently. By contrast, ensembles with electrically independent subcells can achieve lower radiative losses when the subcells are designed for good optical confinement. Distributing electrically independent subcells in a concentrating receiver module allows flexibility in subcell selection and fabrication, and can achieve ultra‐high efficiency with conventional III ‐V cell technology.

Warmann, Emily C.↗
DOE OSTI2020

Surface Modification of Backsheets Using Coupling Agents for Roll-To-Roll Processed Thin-Film Solar Photovoltaic (PV) Module Packaging Application

For many flexible electronic and photonic devices, moisture stability is one of the most important factors that affects its short- and long-term performance. To maintain the performance, the device should be packaged in such a way that it hermetically blocks moisture from the device; however, in practice, it is rather difficult to achieve. The more practical solution is to impede the moisture ingress to the device. In optoelectronic devices that will be outdoors like solar cells, the interfacial adhesion strength between the encapsulant layer (adhesive) and a moisture barrier layer is also a critical parameter. This paper presents surface modifications of poly(ethylene terephthalate) (PET) carrier films, one of the layers in the trilayer barrier film that directly adheres to an encapsulant, using chemical, UV/ozone, and both treatments to improve adhesion with the thermoset encapsulant polymer material. Whereas previous studies also utilized treatment methods to increase the wettability characteristics, in this paper, we not only present the results of the adhesion strength upon various techniques to achieve good adhesion but also screen their behavior upon exposure to a damp–heat (60 °C, 90% RH) environment. Here, we found that the combined treatment method increases the adhesion by up to 12.1-fold and demonstrates up to a 200% increase in adhesion strength even upon our severe damp–heat environmental condition.

36 MATERIALS SCIENCE↗
NASA NTRS1978

High efficiency solar photovoltaic power module concept

The investigation of a preliminary concept for high efficiency solar power generation in space is presented. The concept was a synergistic combination of spectral splitting, tailored bandgap cells, high concentration ratios, and cool cell areas.

Bekey, I.↗
NASA NTRS1986

Crystalline-silicon photovoltaics summary module design and reliability

The evolution of the design and reliability of solar modules was described. Design requirements involved 14 different considerations, including residential building and material electrical codes, wind-loading, hail impact, operating temperature levels, module flammability, and interfaces for both the array structure and the operation of the system. Reliability research involved in diverse investigations including glass-fracture strength, soiling levels, electrochemical corrosion, and bypass-diode qualification tests. Based on these internationally recognized studies, performance assessments, and failure analyses, the Flat-plate Solar Array Project in its 11-year duration served to nuture the development of 45 different solar module designs from 15 PV manufacturers.

Ross, R. G., Jr.↗
NASA NTRS1989

A definition study of the on-orbit assembly operations for the outboard photovoltaic power modules for Space Station Freedom

A concept is described for the assembly of the outboard PV modules for Space Station Freedom. Analysis of the on-orbit assembly operations was performed using CADAM design graphics software. A scenario for assembly using the various assembly equipment, as currently defined, is described in words, tables and illustrations. This work is part of ongoing studies in the area of space station assembly. The outboard PV module and the assembly equipment programs are all in definition and preliminary design phases. An input is provided to the design process of assembly equipment programs. It is established that the outboard PV module assembly operations can be performed using the assembly equipment currently planned in the Space Station Freedom Program.

Sours, Thomas J.↗
NASA NTRS1990

Space Station Freedom electric power system photovoltaic power module integrated launch package

The launch of the Space Station Freedom solar power module requires a weight efficient structure that will include large components within the limited load capacity of the Space Shuttle cargo bay. The design iterations to meet these requirements have evolved from a proposal concept featuring a separate cradle and integrated equipment assembly (IEA), to a package that interfaces directly with the Shuttle. Size, weight, and cost have been reduced as a result.

Nathanson, Theodore H.↗
NASA NTRS2004

Russian Activities in Space Photovoltaic Power Modules with Concentrators

Space concentrator modules with point-and line-focus Fresnel lenses and with reflective parabolic troughs have been developed recently at Ioffe Physico-Technical Institute. PV receivers for these modules are based: on the single junction LPE and MOCVD AlGaAs/GaAs solar cells characterized by AM0 efficiencies of 23.5 - 24% at 20 - 50 suns and 24 - 24.75 at 50 - 200 suns; on the mechanically stacked tandem AlGaAs/GaAs-GaSb cells with efficiency of 27 - 28 at 20 - 100 suns. MOCVD AlGaAs/GaAs cells with internal Bragg reflector have shown a higher radiation resistance as compared to a traditional structure. Monolithic two-terminal tandems AlGaAs (top)-GaAs (bottom) for space application and GaSb (top) - InGaAsSb (bottom) for TRV application are under development as well.

Andreev, Vyacheslav M.↗
DOE OSTI2019

Concentrator-type photovoltaic (CPV) modules, receiver and sub-receivers and methods of forming same

CPV modules include a back plate having an array of 1 mm2 or smaller solar cells thereon. A backplane interconnect network is also provided on the back plate. This backplane interconnect network operates to electrically connect the array of solar cells together. A front plate, which is spaced-apart from the back plate, is provided. This front plate includes an array of primary lenses thereon that face the array of solar cells. The front plate can be configured to provide a greater than 1000× lens-to-cell light concentration to the array of solar cells. To achieve this 1000× lens-to-cell light concentration, the primary lenses can be configured as plano-convex lenses having a lens sag of less than about 4 mm. An array of secondary optical elements may also be provided, which extend between the array of primary lenses and the array of solar cells.

14 SOLAR ENERGY↗
DOE OSTI2020

Dark Lock-in Thermography Identifies Solder Bond Failure as the Root Cause of Series Resistance Increase in Fielded Solar Modules

Correlating the electrical performance of photovoltaic modules to the spatially resolved photoluminescence, electroluminescence, and dark lock-in thermography (DLIT) images is an important long-term goal for developing solar cell technology. These images offer highly sophisticated and detailed information about the spatial distribution and (if imaged at successive time intervals) temporal degradation of local series and shunt resistances. There have been extensive studies to correlate these imaging techniques to local characteristics at the cell level. However, it has been difficult to extract and quantify module-level information from the techniques. In this study, we interpret module current-voltage (I-V) measurements along with corresponding DLIT images within a module-scale simulation framework, demonstrating that series resistance degradation of the module I-V characteristics, in this case, can be attributed to solder bond failures. Our simulations highlight how current crowding associated with a failed solder joint (or a section of the solder pad) translates to the characteristic point-like (asymmetric doublet) heating pattern in neighboring solder joints (or the neighboring regions of the solder pad). Overall, the correlation between series resistance and solder joint degradation could inform expedited diagnosis of field degradation of solar modules.

42 ENGINEERING↗
DOE OSTI2024

Technoeconomic analysis of perovskite/silicon tandem solar modules

Tandem photovoltaic (PV) modules offer an opportunity to improve the efficiency and energy yield of available solar resources compared with single-junction devices. Here, we present a cost model and sensitivity analysis of perovskite/silicon (Si) tandem modules to understand how design choices impact overall module costs. We find a minimum sustainable price (MSP) of $\$$0.428/W DC for our baseline two-terminal design and $\$$0.423/W DC for our baseline four-terminal design, each at a module efficiency of 25% and module production of 3 GW per year in the United States. We find that the choice of Si cell architecture, overall module efficiency, and factory throughput have the most significant impacts on cost and competitiveness. The dynamic model provided is designed for researchers, companies, and interested individuals to use and edit as needed to better understand the trade-offs among PV module technologies and enable targeted research to improve module design and fabrication.

14 SOLAR ENERGY↗
DOE OSTI2022

Automated defect identification in electroluminescence images of solar modules

Solar photovoltaic (PV) modules are susceptible to manufacturing defects, mishandling problems or extreme weather events that can limit energy production or cause early device failure. Trained professionals use electroluminescence (EL) images to identify defects in modules, however, field surveys or inline image acquisition can generate millions of EL images, which are infeasible to analyze by rote inspection. Here, we develop a rapid automatic computer vision pipeline (~0.5 seconds/module) to analyze EL images and identify defects including cracks, intra-cell defects, oxygen-induced defects, and solder disconnections. Defect identification is achieved with a machine learning model (Random Forest, ResNet models and YOLO) trained on 762 manually-labeled EL images of PV modules. We compare model performance on an imbalanced real-world validation set containing 134 EL images and determine that ResNet18 and YOLO are the optimal models; we next evaluated these models on a dedicated testing set (129 module images) with resulting macro F1 scores of 0.83 (ResNet18) and 0.78 (YOLO). Using a field EL survey of a PV power plant damaged in a vegetation fire, we analyze 18,954 EL images (2.4 million cells) and inspect the spatial distribution of defects on the solar modules. The results find increased frequency of ‘crack’, ‘solder’ and ‘intra-cell’ defects on the edges of the solar module closest to the ground after fire. We also find an abnormal increase of striation rings on cells which were assumed to be caused mainly in fabrication process. Our methods are published as open-source software. It can also be used to identify other kinds of defects or process different types of solar cells with minor modification on models by transfer learning.

14 SOLAR ENERGY↗
DOE OSTI2021

Generalizable Mechanistic Understanding of Module-Level Light-Moisture and Thermal-Induced Instabilities in CIGS Photovoltaics (Final Report)

The objectives of this project are to identify the root causes of light, heat and humdity induced instabilities in the operation and accelerated testing of commercial Cu(In,Ga)Se 2 [CIGS] photovoltaic modules produced by major module manufacturers (e.g.: Solibro and MiaSolé), correlate them with module degradation/failure modes, and produce accurate service lifetime prediction models.

14 SOLAR ENERGY↗
DOE OSTI2022

Setting the Bar for Device Performance of Photovoltaic Cells and Modules

Cutting-edge photovoltaic (PV) research and development benefits from NREL's world-record accuracy in device performance measurements. NREL is a global leader for PV calibration services to help control manufacturing quality, assess degradation rates, and develop new technologies.

14 SOLAR ENERGY↗
DOE OSTI2021

Cracked Solar Cell Performance Depends on Module Temperature

When cells in a crystalline silicon photovoltaic module crack, packaging materials hold the fragments together. Changes in module temperature cause cell fragments to move, allowing cracked metallization to lose and regain contact. We intentionally cracked cells in commercial PV modules and characterized the modules’ temperature-dependent electroluminescence (EL) response. Here we show that (1) metallization makes contact across cracks in a way that is temperature dependent and (2) this contact is not a function of temperature, but is hysteretic. We expect that any electro-optical characterization made at a single temperature will be misleading as to the effects of cracked cells at different temperatures. And we expect that a single temperature sweep cannot fully characterize the temperature dependence of electro-optical performance of modules with cracked cells.

crack↗
DOE OSTI2021

Computational Modeling of Photovoltaic Mini-Modules Undergoing Accelerated Stress Testing

A finite element model of a four-cell photovoltaic mini-module was developed and compared to experimental results from an accelerated stress test protocol in order to validate that computational models can accurately represent their physical counterparts when subjected to mechanical loading and to assess mini-module representativeness against full scale photovoltaic modules. Deflected shapes across the simulated mini-modules were compared to measured mini-module shapes when subjected to various pressure loads. Displaced mini-module shape results constrained to the experimental protocols of 0.4 mm and 1.1 mm of displacement at the mini-module center were compared to experimental results of full-size modules subjected to module qualification test load levels of 1.0 kPa and 2.4 kPa, to assess if the bending of mini-modules was representative of full-sized modules under the load. Temperature cycling was incorporated into the model to simulate the impacts of stress due to thermal expansion of the backsheet and cells. A preliminary uncertainty analysis was performed to show how variations in material properties and geometric parameters change the simulation results.

computational modeling↗
NASA NTRS1988

Water-module interaction studies

Mechanisms by which moisture enters photovoltaic modules and techniques for reducing such interactions are reported. Results from a study of the effectiveness of various module sealants are given. Techniques for measuring the rate and quantity of moisture ingress are discussed. It is shown that scribe lines and porous frit bridging conductors provide preferential paths for moisture ingress and that moisture diffusion by surface/interfacial paths is considerably more rapid than diffusion by bulk paths, which implies that thin-film substrate and supersubstrate modules are much more vulnerable to moist environments than are bulk-encapsulated crystalline-silicon modules. Design approaches that reduce moisture entry are discussed.

Mon, G.↗