The next batch of approvals, Secretary Salazar said, “is something that is not months away.”

But even with federal approval, a major hurdle remains for most of the projects: finding excess capacity on transmission lines in the desert, most of which are fully booked or nearly so. At the moment, capacity exists for about 345 megawatts of the 754 megawatts that would eventually be generated by the two newly approved projects.

The rest would require a new line, like San Diego Gas & Electric’s 123-mile proposed Sunrise Powerlink, which has been approved but faces challenges in federal and state courts.

Mr. Salazar emphasized that the Lucerne Valley and Imperial Valley projects had the support of the Natural Resources Defense Council, Defenders of Wildlife and the Wilderness Society.

Both projects were altered to meet environmental objections: they have a smaller footprint than was originally planned and now include greater commitments to mitigate the impact on species like the endangered desert tortoise. Imperial uses minimal water, a scarce resource in the desert. Still, local desert-protection groups remain opposed, and representatives of large environmental groups expressed support in carefully parsed statements.

“These projects were not selected by us,” said Johanna Wald, a senior lawyer with the Natural Resources Defense Council. “They are, as it were, the cards that we were dealt. So we are doing the best that we can by working with the companies, working with the agencies,” to “make them as good as they can be.”

Jim Lyons, who works with renewable energy projects for Defenders of Wildlife, said he supported the Lucerne Valley project. But he said he had some concerns about the impact of the sprawling Imperial Valley solar-reflector project on the landscape, though it has been scaled back from the original 900-megawatt proposal.

“It is smaller, it will go forward in two phases — that certainly is an improvement,” Mr. Lyons said. He said that to achieve such concessions, conservation groups had lodged a formal protest with the Bureau of Land Management, part of the Interior Department.