Reuters: Solar power companies’ shares rallied in early trading on Wednesday, the day after the U.S. Senate voted to extend tax credits worth $18 billion for renewable energy sources. The measure, which the House of Representatives and President George W. Bush are expected to approve, would give businesses a 30 percent tax credit to offset the development costs of solar and other clean energy projects. Among the top gainers on Wednesday was Yingli Green Energy, which rose 9 percent to …