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Results for “Silicon Solar Cells”

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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

Improved silicon solar cells

Redistribution of phosphorus within the n-type layers of n-on-p silicon solar cells results in significant improvements in cell performance. Electrical current output is increased, reduction in current output due to radiation damage is lessened, and very shallow junctions are no longer needed.

Kautz, H. E.↗
NASA NTRS1976

Comparison of type A and C Fluorinated Ethylene Propylene (FEP) as cover materials for silicon solar cells

Fluorinated ethylene propylene film (FEP, 0.0127 cm thick) was heat and pressure laminated to silicon solar cells as a low cost substitute for quartz covers. The FEP-C, treated on one side for bonding, was compared to FEP-A, an untreated FEP. With FEP-A, a silane adhesion promoter was applied to the cells. The FEP-C covers delaminated during accelerated temperature-humidity testing and Earth environmental exposure testing; FEP-A covers were unchanged. No differences were observed in peel tests, but FEP-A is superior in its resistance to tearing and in retention of transmission properties after exposure to ultraviolet radiation.

Broder, J. D.↗
NASA NTRS1976

A study of efficiency in low resistivity silicon solar cells

A general device-analysis program has been utilized to study the efficiency of silicon solar cells. The analysis is applied to specific geometries of both n(+)-p and n(+)-p-p(+) solar cells, and involves a numerical solution of the basic transport and continuity equations. This approach allows solutions that are free of typical limiting assumptions involved in solving the device equations as well as solutions relating to lifetime, mobility variations, and diffused-region profiles. The analysis includes available empirical information on diffusion length, mobility, and lifetime as a function of doping, as well as a Gaussian profile for the diffused region. Results are presented which illustrate the limitations of efficiency as a function of doping. It is found that the maximum efficiencies for both types of cell converge at lower resistivities to around 16% with air-mass-zero radiation and a single-layer absorbing-SiO antireflecting film. It is also found that the minority-carrier lifetime, both in the n(+) surface and p-type bulk regions, presents serious limitations to conversion efficiency, particularly in the low-resistivity cells.

Dunbar, P. M.↗
NASA NTRS1985

Measurement of electrical parameters and current components in the bulk of silicon solar cells

A review and illustration of electrical measurements for determination of the bulk parameters in silicon solar cells is given. The presentation concentrates on transient and small signal admittance measurements. These measurements yield accurate and reliable values of the base lifetime and the surface recombination velocity at the back contract without inaccuracies that normally results from electrons and holes in the p/n junction space charge region. This then allows the determination of the recombination current in each region of the cell. As an example, current components in the emitter, low doped base, high doped base and junction space charge region of the back surface field cell are obtained. Such analysis is essential in determining the relative importance of the base and the emitter and, thus, the region that limits the cell efficiency.

Neugroschel, A.↗
DOE OSTI2024

Innovative recycling of high purity silver from silicon solar cells by acid leaching and ultrasonication

Precious and scarce silver (Ag) is used as a front electrical contact in silicon solar panels. With massive amounts of solar panel waste coming to end-of-life, it is imperative to recover all the Ag from these modules. In this paper, we propose a novel method to easily reclaim Ag from end-of-life silicon solar cells using low concentration sulfuric acid (H 2 SO 4 ) leaching followed by ultrasonication. Our process simplifies the Ag recycling procedure by directly recovering the Ag contacts from solar cells, eliminating the need for secondary precipitation/electrodeposition. First, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) was used to study the leaching and ultrasonication process on rejected solar wafers. Next, a solar panel from landfill was heated in a furnace to burn off the polymer encapsulant. The silicon wafers were then collected from the burning process and leached in 2 M H 2 SO 4 at two different shaking speeds for 48 hours at room temperature. Finally, the end-of-life silicon wafer pieces were collected, sonicated in water, and then the sonication water was centrifuged to show a proof-of-concept to recover the Ag contacts. Inductively coupled plasma optical emission spectroscopy (ICPOES) is used to monitor dissolved elements in the leachate as a function of time and shaking speed. XPS is used to evaluate the composition of the silicon cell wafer surface before and after H 2 SO 4 leaching. SEM is used to image the recovered Ag contacts morphology and EDX confirms the recovered particles contain high amounts of Ag. Furthermore, a proposed schematic illustrates the authors’ hypothesis for the peeling mechanism.

14 SOLAR ENERGY↗
NASA NTRS1980

Study program to improve the open-circuit voltage of low resistivity single crystal silicon solar cells

The results of a 14 month program to improve the open circuit voltage of low resistivity silicon solar cells are described. The approach was based on ion implantation in 0.1- to 10.0-ohm-cm float-zone silicon. As a result of the contract effort, open circuit voltages as high as 645 mV (AMO 25 C) were attained by high dose phosphorus implantation followed by furnace annealing and simultaneous SiO2 growth. One key element was to investigate the effects of bandgap narrowing caused by high doping concentrations in the junction layer. Considerable effort was applied to optimization of implant parameters, selection of furnace annealing techniques, and utilization of pulsed electron beam annealing to minimize thermal process-induced defects in the completed solar cells.

Minnucci, J. A.↗
NASA NTRS1970

Improved protection for silicon solar cells

Fluorinated ethylene propylene /FEP/ film is substituted for epoxy cement in bonding glass covers to silicon solar cells. Insensitivity of FEP to ultraviolet radiation reduces requirement for filtering and does not impair cell performance. Cell costs are reduced and cover mounting is simplified.

Broder, J. D.↗