The Biden administration laid out an ambitious solar power vision Wednesday in a new study from the Department of Energy. It shows that the U.S. has the potential to power about 40% of electricity needs with solar energy — and all in less than 15 years.

Solar energy right now makes up about 3% of the U.S. electricity supply. So, getting to 40% solar by 2035, “it’s a very ambitious goal,” said Kenneth Gillingham, an economics professor at the Yale School of the Environment. “With enough policy support, I do think the numbers are possible.”

Possible, but practical? Not yet. It will take more tax incentives, major upgrades to the electrical grid and quicker permitting processes to reach that level of solar power.

Right now, this is just a blueprint.

Getting to policy is Congress’s job, and that certainty is key for financing, said Abigail Ross Hopper with the Solar Energy Industries Association.

“Well, if you don’t have the certainty, then investors are going to wait, right?” she said. “They’re going to put their capital on the sideline, or they’re going to invest in something that’s a little bit more sure bet.”

But as climate change is already underway, Ross Hopper said there’s not much time to wait.