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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 397 records · Page 22

The Role of Water on the Interfacial Adhesion in Si Solar Modules

Delamination of solar module interfaces often occurs in field-tested solar modules after decades of service due to environmental stressors such as humidity. As water diffuses into the module, failure mechanisms like corrosion and delamination are significantly affected. In the presence of water, the interfaces between EVA and the cell, glass, and backsheet all experience losses of adhesion exposing the module to accelerated degradation. Understanding the relation between interfacial adhesion and water content inside PV modules can help mitigate detrimental power losses. Water content measurements via short wave infrared reflectometry combined with 180 degrees peel tests were used to study and quantify the effect of water ingress and egress on adhesion. Changes in adhesion strength for different module interfaces are quantified, correlating spatial distribution of water content to adhesion for damp heat and dry heat exposed samples. After 1000 hours of damp heat exposure, decreases in adhesion strength of approximately 1 N/mm were noted for all interfaces.

adhesion↗

Upstream Extraction of Tellurium from Copper Concentrates

A major barrier to increasing CdTe PV module production is the availability of tellurium (Te), an element necessary to manufacture CdTe PV cells that currently has a very limited supply. Most Te is obtained from ore extracted for copper mining, but the current processing methods only extract 3-4% of the available Te in this ore, with the rest being discarded during other processing steps. This project aims to increase Te supply by developing an innovative extraction method that will recover more Te from the copper ore earlier in the process. This method will also extract toxic elements like antimony and arsenic, making the copper mining process more environmentally friendly.

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Updates to the Instant Online PV LCOE Calculator Tool

Levelized cost of energy (LCOE) is an important metric for techno-economic analysis of PV modules, systems, and performance. An NREL team within DuraMAT has developed a simplified PV-specific LCOE calculator as an alternative to the NREL System Advisor Model (SAM) for applications that do not have the degree of detail required by SAM. This webinar will review recent data and new features that have been added to the simplified calculator this year, including breakeven buttons, commercial system options, and inverter loading ratios. It will also review the structure of the source code on GitHub, how to edit a local version of the calculator, and walk through some example use cases for the calculator.

calculator↗

Annual Supply Chain for Photovoltaics (ASC-PV) in the United States: 2024 in Review

This report analyzes U.S. PV and BESS supply chains and costs in 2024, for PV module and battery technologies, structural and electrical balance of system (BOS) components, as well as PV recycling. The report concludes with an analysis of technology installation trends, government support for domestic manufacturing, manufacturing jobs, and the domestic content of PV systems installed in the United States in 2024.

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Direct Current Arc-Flash Hazards of Solar Photovoltaic Systems

An arc-flash is a rapid release of thermal energy, pressure waves, and electromagnetic interference from a high-power electrical system, caused by such events as unintentional shorting or equipment malfunction. Arc-flashes are hazardous to people and equipment. Incident energy (IE) is a means of quantifying the degree of thermal hazard posed by an arc-flash event. The calculated IE value dictates what level of personal protective equipment (PPE) workers are required to wear when servicing equipment. Overly burdensome PPE may increase a worker’s discomfort and decrease dexterity, which could lead to unintentional shorting, while inadequate PPE also comes with increased safety risks. The majority of arc-flash research to date has focused on alternating current (ac) systems. For example, IE calculations and PPE for ac systems are relatively well understood and have been applied across many equipment types and voltages. IE calculation methodologies in ac systems are backed by a wide range of industry tests and are included in Institute of Electrical and Electronics Engineers (IEEE) and National Fire Protection Association (NFPA) standards. However, very little is known about direct current (dc) arc-flash and its hazards. This is a significant knowledge gap, as an increasing number of dc systems are being deployed: solar photovoltaic (PV) plants, battery storage, and electric vehicles and their charging infrastructure. The dc arc-flash hazard publications are rooted primarily in theory, and their IE calculation methods contradict each other. Insufficient knowledge and data are preventing the formation of industry consensus and standards around dc arc-flash hazard assessment. Here, this white paper highlights the current status and research opportunities for assessing arc-flash hazards in dc systems, with a focus on PV plants. The nonlinear current-voltage characteristics of PV modules make them unique in comparison to other linear dc sources, such as batteries. Also, PV equipment has rapidly evolved from 600 Vdc to 1,500 Vdc (in the United States), increasing potential arc-flash hazards. The operating regime of a PV-array within its I-V characteristic curve during an arc-flash event and the sustainability of arc-flash events in a utility-scale PV plant need to be investigated. Arc-flash experiments on a 1-MWdc nameplate capacity utility-owned ground-mount photovoltaic plant suggest that the PV array acts as a constant-current supply with currents near the short-circuit portion of the I-V characteristic curve of the array, with median arc voltage as 1/3 of the rated voltage. Various engineering software packages (CYME7 by EATON, PTW by SKM, ArcFlash™ by EasyPower, ETAP, and so on) have started offering dc arc-flash calculation features to estimate the risk of arc-flash in dc and PV systems. However, they are reliant on the same simplified arc-flash models, which contradict each other due to differences in assumptions such as characteristics of the power source, arc current, voltage and impedance, arc-operating regime, and so on. Physical arc-flash testing and improved physics-based modeling with correct assumptions representing practical scenarios are two methods to improve understanding and quantify the risks associated with dc arc-flash hazards. The results would inform development of a more accurate calculation procedure for IE and proper PPE levels.

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Evaluation of the PID-s Susceptibility of Modules Encapsulated in Materials of Varying Resistivity

A common mechanism of potential-induced degradation is by shunting (PID-s) in PV modules, usually associated with the transport of sodium ions (Na+) through the encapsulant and penetrating the front junction of solar cells under voltage stress. Encapsulants with high volume resistivity have been suggested as a potentially cost-effective solution to this degradation mechanism. In this work, we examine three polyolefin elastomer (POE) encapsulants with volume resistivity varying over two orders of magnitude (ranging from 9 x 10^13 to 1 x 10^16 ..omega.. cm) that show equivalent and complete resistance to PID at the damp heat stress test level of 85 degrees C and 85% relative humidity and -1000 V system voltage stress. Performance is compared with a PID-susceptible ethylene vinyl acetate (EVA) encapsulant with resistivity 1 x 10^13 ..omega.. cm. The independence of PID susceptibility with respect to the resistivity of the polyolefin is attributed to the impermeability of POEs to Na + ions. Specific ions (i.e. Na + ), rather than charge-carrying species in general, are responsible for this degradation mechanism.

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Durable Module Materials (DuraMAT) Consortium (Final Technical Report)

The DuraMAT Consortium brings together DOE national lab and university research capabilities with the photovoltaic (PV) and supply-chain industries to accelerate a sustainable, just, and equitable transition to zero carbon electricity generation by 2035 through our five core objectives: development of a central data resource for PV modules, multi-scale and multi-physics modeling, disruptive acceleration science, forensic tools for fielded modules, and materials solutions for more durable, reliable, and resilient modules.

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Review of the environmental effects of the Space Station Freedom photovoltaic power module

An overview is provided of the environment in the low Earth orbit (LEO), the interaction of this environment with the Photovoltaic (PV) Power system of the Space Station Freedom is reviewed, and the environmental programs are described that are designed to investigate the interactions of the LEO environment with the photovoltaic power system. Such programs will support and impact the design of the subsystems of the PV module in order to survive the design lifetime in the LEO natural and induced environment.

Nahra, Henry K.↗

Review of the environmental effects on the Space Station Freedom photovoltaic power module

An overview is provided of the environment in the low earth orbit (LEO), the interaction of this environment with the photovoltaic (PV) power system of the Space Station Freedom is reviewed, and the environmental programs are described that are designed to investigate the interaction of the LEO environment with the photovoltaic power system. Such programs will support and impact the design of the subsystems of the PV module in order to survive the design lifetime in the LEO natural and induced environment.

Nahra, Henry K.↗

Uncertainty Quantification of Bifacial Performance Modeling

Analysis on uncertainty in the annual energy of PV systems that can be attributed to parameters of particular importance to bifacial PV modules is presented. Monte Carlo simulations are used to evaluate the effect of uncertain module bifaciality factors, module transmission fractions, albedo values, and ground clearance. The analyses cover a wide spectrum of potential PV array archetypes through variation of installation parameters. The results of the Monte Carlo analysis reveal that the uncertainty is largely dependent on albedo uncertainty, but more simulations are needed to identify trends across system archetypes. The simulations are aimed at attributing an annual energy uncertainty factor for bifacial considerations that can be applied in post-processing of project probability of exceedance analysis.

energy modeling↗

Uncertainty Quantification of Bifacial Performance Modeling

Analysis on uncertainty in the annual energy of PV systems that can be attributed to parameters of particular importance to bifacial PV modules is presented. Monte Carlo simulations are used to evaluate the effect of uncertain module bifaciality factors, module transmission fractions, albedo values, and ground clearance. The analyses cover a wide spectrum of potential PV array archetypes through variation of installation parameters. The results of the Monte Carlo analysis reveal that the uncertainty is largely dependent on albedo uncertainty, but more simulations are needed to identify trends across system archetypes. The simulations are aimed at attributing an annual energy uncertainty factor for bifacial considerations that can be applied in post-processing of project probability of exceedance analysis.

bifacial↗

Uncertainty Quantification of Bifacial Performance Modeling: Preprint

Analysis on uncertainty in the annual energy of PV systems that can be attributed to parameters of particular importance to bifacial PV modules is presented. Monte Carlo simulations are used to evaluate the effect of uncertain module bifaciality factors, module transmission fractions, albedo values, and ground clearance. The analyses cover a wide spectrum of potential PV array archetypes through variation of installation parameters. The results of the Monte Carlo analysis reveal that the uncertainty is largely dependent on albedo uncertainty, but more simulations are needed to identify trends across system archetypes. The simulations are aimed at attributing an annual energy uncertainty factor for bifacial considerations that can be applied in post-processing of project probability of exceedance analysis.

energy modeling↗

Enhancing lifetime, forecasting, and economic benefits of photovoltaic technologies undergoing UV-induced degradation with optical filtering

Ultraviolet-induced degradation (UV-ID) of various PV cell types was analyzed under optical UV filters with different cutoff wavelengths. Cell types studied included interdigitated back contact (IBC), passivated emitter and rear totally diffused (PERT), and heterojunction technology (HJT) based on crystalline Si (c-Si), and metal halide perovskite (MHP) cells. Analyzing degradation rates in two distinct regimes proved beneficial for all cell types. We used empirical linearizing functions ln(t) for c-Si technologies and 2 √t for MHP samples where t is time. These were applied to extrapolate UV-induced degradation over the lifetime of PV modules under various levels of optical UV filtering and used to predict the relative economic benefits for PV power plants. Degradation rates for all technologies were generally faster under the long pass optical filters having shorter cutoff wavelengths transmitting more UV irradiation and at elevated temperatures when testing MHP samples in the range between 60 °C and 90 °C.

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Multiple Hail Impact Testing

For resilient energy delivery PV modules and systems must withstand extreme weather events such as hailstorms, which are the leading cause of PV insurance claims. Currently, the industry testing is limited to one strike at a time, but in real hailstorms multiple hail strikes can occur within a fraction of a second. In this project we test if multiple simultaneous or near-simultaneous hail strikes cause more damage than with single hail strike testing.

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Bifacial PV System Mismatch Loss Estimation & Parameterization

Non-uniform irradiance on the rear-side of bifacial PV systems can cause additional mismatch loss which may not be appropriately captured in PV energy production estimates and software. We have evaluated several rooftop mounted systems over high albedo reflective roofs. Mismatch losses of up to 2% annual loss for very close-mounted (0.15 m) rooftop systems were found, but losses for high ground-clearance rooftop systems were lower (<0.5%). A simplified empirical relationship was found that links the spatial variation of irradiance (specifically the mean absolute difference of irradiance) to the resulting mismatch loss factor, with a R2 fit better than 0.985. This approximate relationship has been validated by experiments on mismatched PV modules, and provides a basis for fast estimation of bifacial mismatch loss factors for use in hourly PV performance simulations such as PVSyst or SAM.

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Bifacial PV System Mismatch Loss Estimation and Parameterization: Preprint

Non-uniform irradiance on the rear-side of bifacial PV systems can cause additional mismatch loss which may not be appropriately captured in PV energy production estimates and software. We have evaluated several scenarios including horizontal single-axis tracking (HSAT) and rooftop mounted systems over high albedo reflective roofs. Mismatch losses of up to 2% annual loss for very close-mounted (0.15 m) rooftop systems were found, but losses for HSAT systems and high ground-clearance rooftop systems were lower (<0.5%). A simplified empirical relationship was found that links the spatial variation of irradiance (specifically the mean absolute difference of irradiance) to the resulting mismatch loss factor, with a R2 fit better than 0.985. This approximate relationship has been validated by experiments on mismatched PV modules, and provides a basis for fast estimation of bifacial mismatch loss factors for use in hourly PV performance simulations such as PVSyst or SAM.

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Material characterization of seven photovoltaic backsheets using seven accelerated test conditions

A variety of polymeric backsheet materials can be found in fielded photovoltaic (PV) modules, mostly based on fluoropolymer and polyethylene terephthalate (PET) materials. Cost reduction and sustainability considerations drive the recent development of alternative backsheet materials and designs [1]. In some fielded PV installations, polymeric materials are susceptible to environmental degradation in the form of backsheet cracking. To prevent backsheet degradation that can result in a module failure, thorough laboratory reliability testing is needed. In this report we studied the durability of seven commercial and experimental PV backsheets through accelerated stress testing using seven photolytic, hygrometric, and custom tests with the goal to understand if novel fluoropolymer-free backsheets are sufficiently environmentally durable to be commercialized. We divided the mechanisms observed during aging into two categories: core degradation and surface degradation. Although core degradation due to hydrolysis was observed in all commercial PET-, and polyamide (PA)-based backsheets aged with 85 degrees C/85% relative humidity, this test is unlikely to be field relevant. Photo-oxidative reactions on the exposed surface during UV weathering affected all seven backsheets regardless of the outer layer polymer material and additives. This degradation was limited to the outermost micrometers of the surface, except for backsheets containing PA-12, which resulted in surface cracking. A custom test combining UV with water spray caused the most severe backsheet degradation, including surface erosion and loss of insulating properties in polyolefin (PO)- and PA-based backsheets. This highlights the importance of combined accelerated stress testing to screen for complex backsheet degradation mechanisms. We also showed that, with material and design optimization, coextruded experimental PO-based backsheets have the potential to be a durable alternative to commercial PET- and fluoropolymer-based PV backsheets.

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