Every President since Richard Nixon has sought to increase U.S. energy supply diversity. Job creation and the development of a domestic renewable energy manufacturing base have joined national security and environmental concerns as reasons for promoting the manufacturing of solar power equipment in the United States. The federal government maintains a variety of tax credits and targeted research and development programs to encourage the solar manufacturing sector, and state-level mandates that utilities obtain specified percentages of their electricity from renewable sources have bolstered demand for large solar projects. The most widely used solar technology involves photovoltaic (PV) solar modules, which draw on semiconducting materials to convert sunlight into electricity. By year-end 2013, the total number of grid-connected PV systems nationwide reached more than 445,000. Domestic demand is met both by imports and by about 75 U.S. manufacturing facilities employing upwards of 30,000 U.S. workers in 2014. Production is clustered in a few states including California, Ohio, Oregon, Texas, and Washington. Domestic PV manufacturers operate in a dynamic, volatile, and highly competitive global market now dominated by Chinese and Taiwanese companies. China alone accounted for nearly 70% of total solar module production in 2013. Some PV manufacturers have expanded their operations beyond China to places like Malaysia, the Philippines, and Mexico. Overcapacity has led to a precipitous decline in module prices, which have fallen 65%-70% since 2009, causing significant hardship for many American manufacturers. Some PV manufacturers have closed their U.S. operations, some have entered bankruptcy, and others are reassessing their business models. Although hundreds of small companies are engaged in PV-related manufacturing around the world, profitability concerns appear to be driving consolidation, with fewer than a dozen firms now controlling half of global module production. In 2012, the United States imposed significant dumping and countervailing duties on imports of Chinese solar products after ruling that U.S. producers had been injured by dumped and subsidized solar equipment from China. In a second case, the U.S. Department of Commerce (DOC) and the U.S. International Trade Commission (ITC) ruled in 2014 and early 2015 that U.S. producers were being injured by imports of Chinese-made modules that avoided the duties imposed in 2012 by incorporating solar cells from Taiwan. While these duties may help U.S. production become more competitive with imports, the cost of installing solar systems might rise. Domestic demand for solar products may also be depressed by the end of various federal incentives. Unless extended, the commercial Investment Tax Credit for PV systems will revert to 10% from its current 30% rate after 2016, while the 30% credit for residential investments will expire.