"Maryland, where we're based, has good solar energy incentives, but if you look at Virginia right next door, it doesn't," Clifford says. "You don't even need sunshine. Germany doesn't have much of it, but it's a leader in solar energy because of its policies."

While there is still money for which to compete, there has been a rethinking of the whole clean energy market, says Green Strategy's Ballentine.

"The dynamic has changed since 2009," he says. "There's a bit of a de-emphasis on investing in green, simply because some very high expectations have not been met. Some of the money is now going to more later-stage companies rather than start-ups. So the competition among states for money has narrowed somewhat."

While no one is predicting the demise of a green economy in the U.S., some rough moments lie ahead.

Congress has allocated some $3.2 billion in bonds to fund energy programs for states . But tax credits for energy-efficient homeowners expired at the end of 2011, as have some renewable energy grants. A tax credit extension of wind production has stalled in Congress. The current 30 percent tax credit for installing solar panels in homes ends in 2016.

What that means is the clean energy industry may have to find ways to survive on its own.

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