The biggest U.S. solar-panel manufacturer is laying off 2,000 workers and closing factories in response to declining demand and increased competition from China. First Solar Incorporated said Tuesday the layoffs amount to 30 percent of its global workforce. Some cuts come from closing production lines in Malaysia and shutting down a factory in Germany. The company also will cut additional jobs in both Europe and the United States. First Solar said its manufacturing costs should drop by $30 million to $60 million this year and another $100 million to $120 million in 2013. The company said the job cuts are necessary to deal with deteriorating demand in Europe, which has been the biggest market for solar panels.