More Solar

MIT Creates Self-Assembling Solar Cells That Repair Themselves

by Jaymi Heimbuch

MIT's Test Cell Patrick Gillooly, MIT
Solar cells are intended to mimic the photosynthesis of plants -- converting light into energy in the most efficient manner possible. But what other characteristics of plants could be handy for the renewable energy sector to mimic? How about the self-assembly of chloroplast, the component of plants that do all the vital photosynthesis. Leaves repair themselves after sun damage again and again to keep up their ability to convert light into energy. Now, MIT researchers believe they've discovered how to use this self-assembly to restore solar cells damaged by the sun.

Popular Science writes, "To recreate this unique regenerative ability, the MIT team devised a novel set of self-assembling molecules that use photons to shake electrons loose in the form of electricity. The system contains seven different compounds, including carbon nanotubes that provide structure and a means to conduct the electricity away from the cells, synthetic phospholipids that form discs that also provide structural support, and other molecules that self-assemble into "reaction centers" that actually interact with the incoming photons to release electrons."
These compounds can assemble themselves into structures able to harvest solar energy at an efficiency of about 40%. As they loose efficiency from damage, a surfacant can be spread across them to break down the compounds, then when it is filtered out, the cells reassemble good as new. The researchers think they can eventually boost the efficiency even higher, and perhaps provide solar cells that are virtually indestructible.
MIT is constantly coming out with new possibilities for the solar industry, from solar concentrators that improve both efficiency and designs, to printing thin film solar cells on paper. And now, perhaps, solar cells that bring us even closer to completely mimicking leaves.

SkyFuel’s SkyTrough is World’s Most Efficient Solar Concentrator

by Timon Singh

When it comes to producing solar power, efficiency is the key – efficiency of the panels, efficiency of the system’s collectors and, according to SkyFuel, efficiency of the solar concentrator technology. Solar concentrators are increasingly being used in the industry, due to their efficiency in providing cheap solar energy. By harnessing the sun’s energy, a solar concentrator can provide the necessary heat for dozens of homes and thus save electricity. As such, the systems are more efficient than regular solar generators as captured power is not just converted into electricity. But according to SkyFuel, a U.S.-based company, their SkyTrough solar concentrator technology has a thermal efficiency of 73% at 350˚C (662˚F). More than just a shallow claim, their statement has been confirmed by the National Renewable Energy Laboratory (NREL), which has certified the SkyTrough solar concentrator technology to have the highest efficiency in its class!

 

Performance of the optical elements of the SkyTrough was measured at the Optical Efficiency Test Loop in Golden, Colorado. The test facility was designed to allowed the study of the optical performance independent of the receiver’s heat loss characteristics. Optical efficiency is a direct gauge of the design elements unique to the SkyTrough’s mirror reflectance, parabolic accuracy, receiver alignment to the focal line of the trough, and the system’s tracking precision. ”The SkyTrough solar collector is a new, low-weight design that takes advantage of the patented reflector film jointly developed by SkyFuel and NREL,” said Chuck Kutscher, Principal Engineer and Manager of NREL’s Thermal Systems Group.
In a statement from SkyFuel, the company’s Chief Technology Officer Randy Gee said, “A lot of thoughtful engineering went into the SkyTrough, so we were confident our efficiency would be high, but NREL’s confirmation really validates our technology. We couldn’t be more pleased with NREL’s assessment.”
Parabolic trough solar concentrators, such as the SkyTrough, are designed to harness the sun’s energy to make steam for electricity generation. The more efficiently that a trough can harness the sun’s energy and convert it to steam, the more electricity it will be able to make. In the SkyTrough’s case, nearly three quarters of the solar radiation is thus converted into thermal energy, and then into electricity – a very high figure for solar power production. The fact that the thermal-to-electricity loss is only 27% is quite remarkable considering the large losses of efficiency that occur within the industry.

Global Solar rolls out stick-on solar panels

by Martin LaMonica

Glue may be the magic ingredient to making solar power cheaper.
Solar company Global Solar introduced a line of flexible solar modules which are designed for flat commercial rooftop buildings.
Rather than install racking systems to hold heavy glass-covered solar panels, the company's PowerFlex BIPV modules can be adhered onto a roof or built right into roofing materials. The modules are quicker to installer, lighter, and don't require any penetrations into the roof, according to the company.
The installed cost of Global Solar modules is about the same as traditional polycrystalline silicon panels with racks, said Jean-Noel Poirier, the vice president of marketing and business development. But because there is no need for spacing between racks, the flexible thin-film modules can cover more roof space and generate more power, he said.
The company plans to sell its solar modules--long strips of solar panels which almost 19 feet long and one and a half feet wide--through roof membrane manufacturers. The solar cells are made from a combination of copper, indium, selenium, and gallium (CIGS) and perform comparatively well in areas that don't have direct sun, Poirier said.
The company plans to get certification for the modules, which are being evaluated by roofing membrane companies now, by the end of the year and start production early next year.
Global Solar, one of many solar companies developing CIGS solar cells and modules, now has 75 megawatts worth of production capacity at two plants in Tucson, Arizona and Berlin, Germany. Until now, the company has supplied solar cells to panel manufacturers, but the company is now manufacturing its own modules for building-integrated photovoltaics, said CEO Jeff Britt.

New Black Silicon Solar Cells are Cheap and Absorb More Sun

by Brit Liggett

While the reflective and shiny solar panels that researchers have been making thus far look pretty, they’re no match for the National Renewable Energy Laboratory’s (NREL) recently discovered black silicon solar cell. The scientists at NREL discovered that etching thousands of tiny holes into a silicon wafer causes it to be almost black and thus able to absorb almost all of the sun’s rays, and more absorbent solar cells mean more efficient panels.

 

We recently reported on researchers that are using off the shelf dyes to help solar cells absorb a wider range of light but this experiment goes even further. No color can stand up to black when it comes to absorbing . Black doesn’t bounce anything back – it hoards all photons for itself. The researchers got the idea from a team in Munich that had carefully placed a thin layer of gold and some fancy chemicals on their silicon to turn it black.
By mixing gold and chemicals into a cocktail and spraying it on silicon, they were able to create a black silicon wafer in under 3 minutes at room temperature. At 100 degrees Fahrenheit they can do it in less than a minute — this bodes well for mass manufacturing. They call their black silicon wet-etched, because the chemical and gold mixture is wet when applied and etches holes into the substance. Their next effort — and its a big one — is engineering a workable solar panel around their etched silicon.