IBM solar collector magnifies sun by 2,000x

TreeHugger has a post on a new combination concentrating solar PV and concentrating solar thermal power device built by IBM - IBM solar collector magnifies sun by 2,000x (without cooking itself), costs 3x less than similar systems.

Cleverly combining solar PV with solar thermal to reach 80% conversion efficiency

Concentrating the sun's ray onto solar photovoltaic (PV) modules requires walking the fine line between optimizing power output and not literally melting your very expensive super-high-efficiency solar cells. A team led by IBM Research seems to have found a way to push back the line. They have created a High Concentration PhotoVoltaic Thermal (HCPVT) system that is capable of concentrating the power of 2,000 suns onto hundreds of triple junction photovoltaic chips measuring a single square centimeter each (they even claim to be able to keep temperatures safe up to 5,000x). The trick is that each solar PV cell is cooled using technology developed for supercomputers; microchannels inspired by blood vessels but only a few tens of micrometers in width pipe liquid coolant in and extract heat "10 times more effective than with passive air cooling."

The beauty is that this heat is not just thrown away. This system gets useful work out of it. So while the PV modules are 30%+ efficient at converting the sun's light into electricity, another 50% of the sun's energy is captured as heat and can then be used to do things like thermal water desalination and adsorption cooling. This means that the system is capable of converting around 80% of the collected solar energy into useable energy (though the electricity is of course more useful than the thermal energy).

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Australia’s largest concentrated solar power plant officially launched

RenewEconomy has an article on Silex's CPV (Concentrated Solar Photovoltaic) power plant at Mildura - Australia’s largest concentrated solar power plant officially launched.

Australia’s largest concentrated photovoltaic (CPV) solar power plant was officially opened today, with the Victorian energy minister joining executives from the plant’s developer, Solar Systems, to cut the ribbon on the 1.5MW demonstration facility in Mildura.

The demonstration of the “dense array” solar technology of parent company Silex Systems is a fore-runner for what is expected to be a 100MW power plant, with construction slated to begin in 2014. Another 1MW demonstration plant is being built in Saudi Arabia, with hopes of further development as that country pushes into the start of a $100 billion solar spending program

The array – whose 40 CPV dishes have been feeding power into the national grid for almost a month, after their successful commissioning began in April – collects sunlight in more than 100 curved mirrors and focuses it onto ultra-high efficiency “mulit-junction” PV cells; technology originally developed by Boeing to power satellites.

Silex CEO Michael Goldsworthy says the cells currently boast efficiency rates of around 43 per cent – about double that of today’s best silicon-based cells and up to four times the efficiency of thin film solar cells – but he hopes this can be lifted to more than 50 per cent, or even 60 per cent, with further research.

The technology also uses ‘active cooling’ technology to maximise power output while minimising water consumption and prolonging the technology’s lifespan.

Last June Silex predicted that the levelised cost of energy (LCOE) for its technology could fall below 10c/kWh ($100/MWh) within a few years – making it cost competitive with a range of technologies such as wind and large-scale solar PV, and below the cost of new gas- and coal-fired generation.

While PV solar in it's various forms has dominated the solar power market in recent years, it seems solar thermal power is still attracting some interest, with a Vast Solar pursuing a plant in western NSW - Plans for Forbes solar thermal project

A solar thermal project near Forbes will demonstrate how cost effective renewable energy can be once its development application is approved. Three-and-a-half thousand moving mirrors, each bigger than a plasma television, will follow the sun like a field of sunflowers. The mirrors will reflect light onto five thermal receivers sitting on towers that will heat a central steam turbine, capable of producing 1.1 megawatts of electricity.

The company behind the project, Vast Solar, already has 700 mirrors and one tower at Jemalong Station. ... The company’s plan is to use a method called air condenser cooling.

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Ultra-Efficient Solar

Technology review has a look at Semprium's approach to high efficiency solar cells using concentrating lenses and gallium arsenide cells - Ultra-Efficient Solar.

This past winter, a startup called Semprius set an important record for solar energy: it showed that its solar panels can convert nearly 34 percent of the light that hits them into electricity. Semprius says its technology, once scaled up, is so efficient that in some places, it could soon make electricity cheaply enough to compete with power plants fueled by coal and natural gas.

Because solar installations have many fixed costs, including real estate for the arrays of panels, it is important to maximize the efficiency of each panel in order to bring down the price of solar energy. Companies are trying a variety of ways to do that, including using materials other than silicon, the most common semiconductor in solar panels today.

For example, a startup called Alta Devices (see the TR50, March/April 2012) makes flexible sheets of solar cells out of a highly efficient material called gallium arsenide. Semprius also uses gallium arsenide, which is better than silicon at turning light into electricity (the record efficiency measured in a silicon solar panel is about 23 percent). But gallium arsenide is also far more expensive, so Semprius is trying to make up for the cost in several ways.

One is by shrinking its solar cells, the individual light absorbers in a solar panel, to just 600 micrometers wide, 600 micrometers long, and 10 micrometers thick. Its manufacturing process is built on research by cofounder John Rogers, a professor of chemistry and engineering at the University of Illinois, who figured out a way to grow the small cells on a gallium arsenide wafer, lift them off quickly, and then reuse the wafer to make more cells. Once the cells are laid down, Semprius maximizes their power production by putting them under glass lenses that concentrate sunlight about 1,100 times.

Concentrating sunlight on solar panels is not new, but with larger silicon cells, a cooling system typically must be used to conduct away the heat that this generates. Semprius's small cells produce so little heat that they don't require cooling, which further brings down the cost. Scott Burroughs, Semprius's vice president of technology, says utilities that use its system should be able to produce electricity at around eight cents per kilowatt-hour in a few years. That's less than the U.S. average retail price for electricity, which was about 10 cents per kilowatt-hour in 2011, according to the U.S. Energy Information Administration.

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