Visitors to Thalheim in eastern Germany enter a grey landscape of abandoned industrial buildings, the remnants of the communist-era chemicals industry. Yet amid the blight, a few dozen shiny low-lying factories provide signs of a long hoped for revival. Dubbed the Solar Valley, the area around the town south of Berlin is at the heart of one of Germany's newest high-technology industries, manufacturing the cells and other components needed to generate sun-powered renewable energy. Eastern Germany now boasts the world's largest concentration of such companies: 40 businesses, many foreign-owned, employing an estimated 12,000 staff, have found greenfield sites here. Others are queuing to invest, keen to supply directly to the German customers who form the world's largest market for solar panels. Another 24,000 jobs are expected by 2020, industry officials say. The trend has been embraced by Angela Merkel, the chancellor, who has led calls for a shift to renewable energy to slow down climate change. An easterner herself, she is keen to support a region that, in spite of pockets of sustained growth, is still struggling to cling to the west's economic coat-tails. Yet critics argue that this mini-revolution has a darker side. Trade unionists and local politicians, while pleased with the new jobs, have filed complaints with some of the solar companies over low wages, difficult working conditions and hostility towards or