Wednesday, March 28, 2012

Hot news in cleantech: Solar, cheap at half the price

Cheaper, more efficient solar! NOW! That’s been the name of the game in cleantech over the past week, with three different US solar cell makers touting new technological developments: two claiming they could halve the per Watt cost of solar power; one claiming it could produce 200 per cent the power of conventional solar cells.
Let’s begin with California-based start-up Twin Creeks Technologies, which gained media attention last week (Technology Review says the company had been “operating in secret” until that time) with the claim that its manufacturing equipment could produce solar cells for 40 cents per watt, about half today’s leading 80 cents per watt. As reported on CleanTechnica, the company claims that wafers produced on its Hyperion manufacturing system are less than one-tenth as thick as conventional wafers. Twin Creeks also says that these 20-micrometer-thick wafers can be produced with less raw material – 90 per cent less silicon, for starters – and less capital-intensive manufacturing equipment. This all translates to solar panels that sell for nearly 50 per cent less than conventional panels, as well as new generations of inexpensive semiconductors. It also reduces companies’ exposure to silicon price swings, says Twin Creeks. Meanwhile, the extreme slenderness of the Si cells has the added bonus of making them bendable, rendering the “traditional glass sandwich” unnecessary. Instead, the “ultra-thin modules can be wrapped in a flexible encapsulant, reducing both weight and cost,” says Twin Creeks.
The company’s primary plan, says Technology Review, is to sell manufacturing equipment, rather than produce solar cells. “I expect that by this time next year, we’ll have a half a dozen to a dozen of these tools in the field,” says Twin Creeks CEO Siva Sivaram. The technology has been tested in a small, 25MW-per-year solar-cell factory the company built in Mississippi, and while one of its advantages is that it can be added to existing production lines, it does require one change, says TR: the implementation of an alternative anti-reflection technology to that used in the conventional production process. For those who would like a more detailed description of how the Twin Creeks solar cell manufacturing process works, Technology Review has that covered.
Now to the second company that aims to cut the cost of solar cells in half: Colorado-based Ampulse Corporationdescribed by CleanTechnica as another solar industry up-comer, this week revealed it has made radical changes to the production process of solar cells it claims can push the prices of solar power to less than $0.50 per watt. Ampulse aims to do this by reducing the use of silicon wafers – accountable for about half the cost of a typical solar panel – while still using silicon as the core material in its thin-film crystalline silicon (c-Si) PV cells, says CleanTechnica. It does this by growing the silicon on an inexpensive, textured metal foil by using a chemical vapor deposition process. This requires less heat than the manufacturing of traditional silicon wafers, and also results in a much thinner wafer, less than 10 microns. Ampulse also bypasses the sawing phase of manufacturing, which usually results in a loss of half of the refined silicon.
According to Ampulse CEO Steven Hane, solar panels using the company’s wafers will cost less then 50 cents per watt, with an efficiency of 15 per cent. But not just yet. The company is installing a new pilot manufacturing facility in National Renewable Energy Laboratory’s (NREL) Process Development Integration Laboratory (PDIL), but is already planning stages of a full-scale production line. As well as NREL, it has development agreements with Oak Ridge National Laboratory, and almost $US1.5 million in funds dedicated to further research.
And back to California now, to another would-be solar cell trailblazer, Solar3D, which this week announced the completion of a “detailed simulation analysis comparing its breakthrough solar cell with conventional solar cells,” which it says turned up the rather dramatic finding that its solar cell “can produce 200 per cent of the power output of conventional solar cells.” The company says its “innovative single wafer silicon solar cell is based on a 3-dimensional design with two very powerful and unique patent-pending features: wide angle light collection and high conversion efficiency.” The wide angle feature is kind of self-explanatory – it creates greater surface area to capture more light at sunset and sunrise and in winter months – while the 3-dimensional design increases electricity generation efficiency by trapping sunlight inside photovoltaic microstructures, which are etched into the wafer, where photons bounce around until they are converted into electrons.
Solar3D says its analysis – which CleanTechnica points out is neither based on a working prototype, nor is it independently verified – indicates that, while a typical 17 per cent efficient solar cell performs more like a 5 per cent efficient cell when the sun is not directly overhead, its Solar3D cell can maintain its high 25 per cent efficiency for a longer period of time and can generate 200 per cent of the power output of conventional solar cells. This translates to an estimated 40 per cent reduction in the payback period of a fully installed Solar3D panel array, the company says. “With Solar3D cells, utility solar farms can be smaller in size and easier to operate without the need for mechanical systems to track the sun,” says the company’s CEO, Jim Nelson. “Space limited applications, such as rooftops, can finally generate enough useful power to successfully compete against other sources of electricity. We believe that our 3D design is a game changer.” The company is currently working on a prototype 3D solar cell.

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