The solar power industry may be in a state of oversupply, but that doesn't mean demand for polysilicon solar panels has dropped off. China's ET Solar Group Corp., a maker of silicon ingots, wafers and solar panels, proved the point Tuesday when it announced a deal to sell 13 megawatts of panels to German solar integrator and distributor USE between this month and November. How much USE is paying ET wasn't disclosed by the companies. But given comments from the world's largest makers of polysilicon photovoltaic solar panels in recent months, it's likely the price has fallen since ET first sold panels to USE in the second half of last year. Suntech Power Holdings (NYSE: STP), which earlier this month said it had grown to be able to manufacture 1 gigawatt of solar panels per year, has cut its sales forecast for last year and predicts a 25 percent to 30 percent drop in the prices it will be able to command in the coming year. An oversupply of polysilicon is to blame, CEO Zhengrong Shi said — a warning that has been matched by other solar companies and analysts. While demand for polysilicon to make solar panels should grow 34 percent next year, supply will probably double, research firm iSupply predicted in November. That could drive spot market prices for polysilicon to $200 per kilogram next year, down from highs of $500 per kilogram in 2008.  Germany's Q-Cells, which expects 2009 production to reach 800 megawatts to 1 gigawatt, also slashed its 2009 production and sales forecasts last month, citing customers' decisions to delay deliveries of already-booked orders. The weakening economy was to blame, the company said.