The Interior Department issued a new plan Thursday for promoting large-scale solar development on public lands in the West, identifying 285,000 acres — 445 square miles — in six states where it pledged to help speed up the permitting process.

The proposal drew praise from environmentalists but a more tepid response from solar industry officials, who warned that the “solar energy zone” approach outlined by the Obama administration might complicate efforts to erect large-scale projects on federal lands.

Interior officials said they would accelerate permit approvals in 17 zones in Arizona, California, Colorado, New Mexico, Utah and Nevada. An earlier version of the proposal called for creating 24 zones across 667,000 acres in those states.

Interior Secretary Ken Salazar said department officials hoped to steer projects to areas where there would be less chance of conflicts over environmental issues, such as endangered species, and closer proximity to electricity transmission lines. Environmental activists have sometimes challenged large-scale solar projects on the grounds that they could damage critical habitat.

“These 445 square miles are where the sweet spots are, so that’s where development will be driven,” Salazar told reporters in a telephone news conference. “There will be a strong incentive for solar energy development to come into these zones.”

Deputy Interior Secretary David J. Hayes emphasized that the new rules would allow for the creation of additional solar energy zones and would not block development outside of these designated areas. In those instances, Hayes said, “the developer will have to make a stronger case” to win a federal permit.

Federal permitting for solar development has moved relatively slowly. The George W. Bush administration did not issue any permits, while the Obama administration has approved 22 projects on public land, 13 of which were solar; none of the solar projects are operating yet. The rest are geothermal and wind projects. Steve Black, counselor to Salazar, said the department anticipates that as many as 14 additional solar projects in Arizona, California and Nevada could win approval in 2012.

There are 79 pending applications for utility-scale solar projects on 685,000 acres of federal land, roughly 85,000 acres of which overlap with the newly proposed solar energy zones.

Jim Lyons, senior director for renewable energy at Defenders of Wildlife, said the new policy represents the first time the federal government has sought a comprehensive balance between environmental and energy needs when it comes to energy development on public land.

“Right now it’s, ‘Y’all come,’ ” Lyons said in an interview, referring to oil and gas operations.

While solar companies might be disappointed by the limitations of the zones, he added, “this provides the certainty and flexibility that could accelerate the deployment of solar energy on public lands.”

But the announcement may not sway some major solar developers who have already moved on from federal lands.

Recurrent Energy chief executive Arno Harris, whose firm ranks as one of the top solar developers in North America, said that because a site needs to be selected years before a project is up and running, “the news is unlikely to change our land strategy, which has focused on private lands close to existing transmission that avoid sensitive environmental or species habitats.”

Rhone Resch, president and CEO of the Solar Energy Industries Association, expressed some concern about the plan. The proposal will be subject to a 90-day comment period and won’t become final until next year.

“While we are still reviewing all of the details in this proposal, there are some significant areas of concern regarding the viability of a solar-energy zone approach,” he said in a statement.