PORTLAND, Ore. -- Petitions for tax subsidies targeted to solar and other clean energy projects are pouring into the state Department of Energy, resulting in a backlog of more than three months.

That's frustrating for businesses trying to meet tight construction deadlines and negotiate financing.

Michael Grainey, director of the state Department of Energy, told The Oregonian that most requests are dealt with in a month. He says the backlog is due to the program's popularity and an overwhelmed staff.

The 2007 Legislature doubled the business energy tax credit, but it provided no new money to increase staff.

The projects include everything from energy-saving lighting systems to large wind farms; many are rooftop and ground-mounted solar electric systems.