BOSTON — A Massachusetts company has won a conditional $150 million federal loan guarantee to develop a dramatically cheaper way to produce the silicon wafers that are the key component of solar panels.Department of Energy Secretary Steven Chu on Friday called the project by 1366 Technologies Inc. a “game changer” that could slash the price of solar power by cutting the wafers’ manufacturing costs in half.”It is exactly the kind of innovation that puts America at the forefront of the global clean energy race,” Chu said.The wafers are 6-by-6-inch squares — less than eight-thousandths of an inch thick — that are converted to solar cells and joined together to make the main part of a solar panel.The 1366 Technologies process makes the wafers by individually forming them from a pool of molten silicon, then freezing them. The company says it’s far cheaper than the current method of using wires to saw the ultra-thin wafers from chunks of silicon.”We’re not inventing a product, we’re inventing a process,” said Craig Lund, the company’s vice president of business development. “[It’s] the same product, but a much more streamlined, efficient process.”The U.S. has a small but growing 5 percent to 7 percent market share of the world’s solar energy industry, according to a report for the Solar Energy Industries Association. China and Germany are leading players in the market.The price of solar energy is a major competitive disadvantage, even compared to other renewable sources of electricity.A U.S. Energy Information Administration projection of the cost of electricity from new plants coming on line in 2016 puts the cost of solar at 21.1 cents per kilowatt hour. It’s cheaper than offshore wind (24.3 cents) but much more expensive than land wind (9.6 cents) and conventional coal (9.5 cents), for instance.But 1366 Technologies says its manufacturing process can chop the price of solar electricity down to about 4 cents per kilowatt hour by 2020.The Lexington-based company, founded in 2007, has previously received two Department of Energy grants worth a combined $7 million to help develop its technology.As a condition of the $150 million loan, the company must complete financial and legal documentation, and it’s confident it will quickly do so, Lund said. The money will be distributed over time, depending on progress, he said.The loan, Lund said, is “huge for us.””It gives us an opportunity to become a global player in the market for silicon wafers, [on a] much faster more efficient timeline than we could do otherwise,” he said.The company plans to have a small manufacturing plant in Lexington running by 2013. Assuming all goes well there, it plans to have a far larger facility running by 2016 at a still undetermined location, and aims to eventually make enough wafers to produce 1,000 megawatts of electricity annually.Monique Hanis of the Solar Energy Industries Association, who declined to speak about individual companies or technologies, said any breakthrough technologies are obviously welcome but have to prove they can be manufactured economically on a large scale.Even without such advances, there are many ways to reduce the cost of solar energy, such as a broad manufacturing expansion, which will increase efficiency and drive down costs, Hanis said. Streamlining solar installations, reducing financing costs and unclogging the permitting process are other ways, she said.”We’re not all waiting for the one silver bullet, game-changing technology that’s going to bring the price down,” Hanis said.