Amidst intense scrutiny of the Department of Energy's loan guarantee program via the Solyndra scandal, September has still emerged as critical for a series of solar companies that hope to close federal loan guarantees and start construction on solar farms by the end of the month. First Solar, for one, received the final permit for its 550 MW Topaz Solar project in San Luis Obispo County in California yesterday, said the county's senior planner, John McKenzie. With that construction permit, First Solar plans to start building Topaz by Sept. 30, said company spokesman Alan Bernheimer. Meeting that deadline will ensure the company remains eligible for a loan guarantee from the Department of Energy that will back part a $1.93 billion loan led by the Royal Bank of Scotland.