WASHINGTON — President Joe Biden ordered emergency measures Monday to increase U.S. manufacturing of solar panels and declared a two-year tariff exemption on panels from Southeast Asia as he attempted to jumpstart an industry key to his climate change-fighting goals. His invoking of the Defense Production Act and other executive actions comes amid complaints by industry groups that the solar sector is being slowed by supply chain problems due to an ongoing Commerce Department inquiry into possible trade violations involving Chinese products. The Commerce Department announced in March that it was scrutinizing imports of solar panels from Thailand, Vietnam, Malaysia and Cambodia, concerned that products from those countries are skirting U.S.