Two solar manufacturers are begging the federal government for help, arguing that without protection from a flood of cheap imports, the United States risks losing its own domestic solar industry. But as they made their arguments before a commission on Tuesday, they faced an opponent: much of the rest of their industry.In a hushed, wood-paneled hearing room in the heart of Washington, D.C., companies Suniva and SolarWorld urged the United States International Trade Commission to impose steep tariffs on imports of solar cells and modules, which are assembled into panels and used to harvest solar energy, under a rarely used section of U.S.