Other companies have made thin wafers of silicon using new sawing techniques or other methods. But other approaches tend to produce fragile wafers, and they can’t be used with existing cell manufacturing equipment. Rajesh Rao, the company’s director of technology, says the metal backing on Astrowatt’s cells makes them more durable.
The company has demonstrated the technology in the lab, making large, eight-inch-wide wafers and small solar cells that are nearly 15 percent efficient. That’s slightly less efficient than conventional crystalline silicon solar cells, but the researchers haven’t yet applied all of the known methods for increasing solar-cell efficiency. In fact, the cells could theoretically reach higher efficiencies than conventional silicon solar cells because they’re thinner, which makes it easier for electrons to exit the cell to generate electricity.
The next step is to demonstrate the process on commercial-scale equipment. Almost all of the steps in the process can be done on machines already found in solar-cell factories.
So far, Astrowatt has raised an undisclosed amount in an initial round of venture capital investment, along with $1.5 million under the U.S. Department of Energy’s Sunshot initiative, which aims to make solar power competitive with electricity from fossil fuels.
The approach does have some drawbacks. The metal-silicon films curl up slightly, which makes them somewhat difficult to handle on a conventional production line. Also, unlike some other approaches, this one doesn’t completely eliminate the need to make a block of crystalline silicon and saw into it, although it does greatly reduce the amount of sawing needed.
Other approaches, such as one being developed by startup 1366 Technologies, aim to eliminate these steps altogether, which could further reduce manufacturing costs. That technology, however, has challenges of its own, including achieving high yields and producing high-quality silicon.
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