Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have set a world record in solar cell efficiency with a photovoltaic device that converts 40.8 percent of the light that hits it into electricity. This is the highest confirmed efficiency of any photovoltaic device to date.

The inverted metamorphic triple-junction solar cell was designed, fabricated and independently measured at NREL. The 40.8 percent efficiency was measured under concentrated light of 326 suns. One sun is about the amount of light that typically hits Earth on a sunny day. The new cell is a natural candidate for the space satellite market and for terrestrial concentrated photovoltaic arrays, which use lenses or mirrors to focus sunlight onto the solar cells.

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University of Utah engineers have devised a new way to slice thin wafers of the chemical element germanium for use in the most efficient type of solar power cells. They say the new method should lower the cost of such cells by reducing the waste and breakage of the brittle semiconductor.

The expensive solar cells now are used mainly on spacecraft, but with the improved wafer-slicing method, “the idea is to make germanium-based, high-efficiency solar cells for uses where cost now is a factor,” particularly for solar power on Earth, says Eberhard “Ebbe” Bamberg, an assistant professor of mechanical engineering. “You want to do it on your roof.”

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Researchers at the US Department of Energy’s Idaho National Laboratory (INL), have devised an inexpensive way to produce plastic sheets containing billions of nanoantennas that collect heat energy generated by the sun and other sources.

While methods to convert the energy into useable electricity still need to be developed, the sheets could one day be manufactured as lightweight ‘skins’ that power everything from hybrid cars to iPods with higher efficiency than traditional solar cells, say the researchers. The nanoantennas also have the potential to act as cooling devices that draw waste heat from buildings or electronics without using electricity.

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Sanyo Electric’s proprietary solar cell, the ‘heterojunction’ with intrinsic thin layer (HIT), has achieved a cell conversion efficiency of 22.3 per cent.

The latest conversion efficiency is an official record that was measured by Japan’s National Institute of Advanced Industrial Science and Technology (AIST). The cell measures 100.5cm2. It has a short-circuit current of 3.909A, an open-circuit voltage of 0.725V and a fill factor of 79.1 per cent. The maximum power per cell is 2.242W.

According to Sanyo, two key points improved the performance of the latest cell. In a HIT solar cell composed of a crystalline silicon layer sandwiched by amorphous silicon layers, the company improved the technology to wash the surface of the crystalline silicon layer prior to the formation of the amorphous silicon layers. The company also optimised the size and the shape of irreguarlities on the cell surface, which are provided to prevent reflection.

The company aims to enhance the cell conversion efficiency to 23 per cent at the research level, and to 22 per cent or higher at the mass production level by fiscal 2010.

An innovative way of capturing energy from the sun could increase the amount of power generated by solar panels.

The concept devised by engineers from the Massachusetts Institute of Technology (MIT), centres on a ‘solar concentrator’. The solar concentrator evolved from a similar idea developed in the 70’s that involved impregnating dyes in plastic. The idea was abandoned because, among other things, not enough of the collected light could reach the edges of the concentrator. The MIT engineers decided to apply this technique to its solar concentrator.

The MIT solar concentrator comprises a mixture of two or more dyes in specific ratios, which is painted onto the surface of a pane of glass or plastic. The dyes work together to absorb light across a range of wavelengths, which is the re-emitted at a different wavelength and transported across the pane to waiting solar cells.

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Surrey Nanosystems is to supply Ludwig-Maximilians University (LMU) with an advanced spluttering tool, to aid its research into the fabrication of hybrid solar cells.

The tool will be used by researchers in LMU’s Department of Physics and Centre for NanoScience, to develop production techniques that utilise precisely ordered nanowire structures as templates for organic material.

Compared with conventional silicon-based solar energy systems, such new generations of hybrid solar cells have the potential to dramatically lower costs, and provide ‘free’ power for consumer electronics products. By building arrays of organic solar cells on a low-resistance nanowire interconnection substrate, LMU expects to increase the efficiency of the energy conversion process.

To spur new development and demand for renewable energy sources, Intel Corporation is spinning off key assets of a start-up business effort inside Intel’s New Business Initiatives group to form an independent company called SpectraWatt.

SpectraWatt will manufacture and supply photovoltaic cells to solar module makers. Solar cells are the discrete components in a solar energy generation system responsible for converting sunlight to electricity.  In addition to focusing on advanced solar cell technologies, SpectraWatt will concentrate development efforts on improvements in current manufacturing processes and capabilities to reduce the cost of photovoltaic energy generation. SpectraWatt expects to break ground on its manufacturing and advanced technology development facility in Oregon in the second half of 2008 with first product shipments expected by mid-2009.

Commenting on the formation of the new company, Andrew Wilson, SpectraWatt CEO and former general manager in the Intel New Business Initiatives group, said: “The formation of SpectraWatt is an important step forward in the renewable energy market.”