By Jeff Mason WASHINGTON (Reuters) -President Joe Biden waived tariffs on solar panels from four Southeast Asian nations for two years and invoked the Defense Production Act to spur solar panel manufacturing at home, the White House said on Monday, confirming a Reuters report. The tariff exemption applies to panels from Cambodia, Malaysia, Thailand and Vietnam and will serve as a “bridge” while U.S. manufacturing ramps up, the White House said. Shares in U.S. solar companies including SunPower Corp, Enphase Energy Inc and Sunrun Inc climbed after Reuters earlier reported that Biden would issue…