BP Solar

About: BP Solar is a based out in . It is known for research contribution in the topics: Silicon & Solar cell. The organization has 202 authors who have published 156 publications receiving 3826 citations.

Photovoltaic module framing system with integral electrical raceways

Abstract: A multi-purpose photovoltaic module framing system is provided which combines and integrates the framing system with the photovoltaic electrical system. The user friendly framing system is easy to install and can be directly mounted to a roof surface without auxiliary brackets and beams. The economical framing system has aesthetically pleasing frames to mechanically hold and support photovoltaic modules. The multi-purpose frames desirably have integral electrical raceways which conceal and protect most electrical components and wires. The reliable frames are specially constructed and arranged to permit easy access to output wires and do not require junction boxes. Ground clips can be directly connected to the convenient framing system.

Very high efficiency solar cell modules

Abstract: The Very High Efficiency Solar Cell (VHESC) program is developing integrated optical system–PV modules for portable applications that operate at greater than 50% efficiency. We are integrating the optical design with the solar cell design, and have entered previously unoccupied design space. Our approach is driven by proven quantitative models for the solar cell design, the optical design, and the integration of these designs. Optical systems efficiency with an optical efficiency of 93% and solar cell device results under ideal dichroic splitting optics summing to 42·7 ± 2·5% are described. Copyright © 2008 John Wiley & Sons, Ltd.

Casting Single Crystal Silicon: Novel Defect Profiles from BP Solar's Mono2 TM Wafers

Abstract: A novel crystal growth method has been developed for the production of ingots, bricks and wafers for solar cells. Monocrystallinity is achievable over large volumes with minimal dislocation incorporation. The resulting defect types, densities and interactions are described both microscopically for wafers and macroscopically for the ingot, looking closely at the impact of the defects on minority carrier lifetime. Solar cells of 156 cm2 size have been produced ranging up to 17% in efficiency using industrial screen print processes.

Chemical Natures and Distributions of Metal Impurities in Multicrystalline Silicon Materials

Abstract: We present a comprehensive summary of our observations of metal-rich particles in multicrystalline silicon (mc-Si) solar cell materials from multiple vendors, including directionally-solidified ingot-grown, sheet, and ribbon, as well as multicrystalline float zone materials contaminated during growth. In each material, the elemental nature, chemical states, and distributions of metal-rich particles are assessed by synchrotron-based analytical x-ray microprobe techniques. Certain universal physical principles appear to govern the behavior of metals in nearly all materials: (a) Two types of metal-rich particles can be observed (metal silicide nanoprecipitates and metal-rich inclusions up to tens of microns in size, frequently oxidized), (b) spatial distributions of individual elements strongly depend on their solubility and diffusivity, and (c) strong interactions exist between metals and certain types of structural defects. Differences in the distribution and elemental nature of metal contamination between different mc-Si materials can largely be explained by variations in crystal growth parameters, structural defect types, and contamination sources. Copyright © 2006 John Wiley & Sons, Ltd.

Impact of Metal Contamination in Silicon Solar Cells

Abstract: Summary The impact on solar cell performance of transition metals like iron, chromium, nickel, titanium and co pper is the topic of this extended abstract. Each impurity has been intentionally added to silicon feedstock used to gr ow p-type directionally solidified multicrystalline silicon i ngots. A state of the art screen print solar cell process ha s been applied to wafers cut from the bottom to the top of these ingots. Adding 50 ppmwt of iron or 40 ppmwt of nickel or chromium to silicon feedstock, results in comparabl e solar cell performances to reference uncontaminated material in the range 40% to 70% of the ingot height. Addition of 10 ppmwt of titanium dramatically reduces the efficien cy along the entire ingot. Impurities like iron, chromium an d titanium cause a reduction in the diffusion length. Nickel d oes not reduce the diffusion length. On the other hand affe cts strongly the emitter recombination reducing the sol ar cell performance significantly. Copper has the peculiari ty to impact both bulk recombination as well as emitter recombination. A model based on Scheil distribution of impurity ha s been derived to fit the degradation along the ingot. So lar cell performance has been modeled as function of base bulk recombination and emitter recombination. The model fits very well the experimental data and has been also successfully validated. Unexpectedly, the Scheil di stribution of impurity along the ingot leaves its finger-print also at the end of the solar cell process. A measure of impurit y impact has been defined as the level of impurity which cau ses a degradation of less than 2% up to 90% of the ingot height. The advantage of this parameter is that comprises t he different impurities physical characters in one sin gle parameter, easy to compare.