President Obama made a political and an economic case for solar energy Monday, telling an industry summit in Las Vegas that the explosive growth in solar power “has some big fossil fuel interests pretty nervous.”

“Now, it’s one thing if you’re consistent in being free market. It’s another thing when you’re free market until it’s solar that’s working and people want to buy and suddenly you’re not for it any more,” he said.

“When you start seeing massive lobbying efforts backed by fossil fuel interests, or conservative think tanks, or the Koch brothers pushing for new laws to roll back renewable energy standards, or to prevent new clean energy businesses from succeeding, that’s s problem,” Obama said, singling out industrialists Charles and David Koch for the first time in a climate speech.

“That’s not the American way. That’s not progress. That’s not innovation. That’s rent seeking. That’s standing in the way of progress,” Obama said.

Koch-backed groups have fought clean energy mandates in several states, comparing the policies to the health insurance mandates under Obamacare. “Koch Industries supports all forms of energy, but we believe they need to stand on their own merits,” said Philip Ellender, Koch Industries’ president of public affairs, in response to Obama’s speech. “We will continue to call them what they are – corporate welfare.”

Obama acknowledged that there are legitimate issues to be worked out — like who pays for power transmission when solar generation is largely decentralized. But Obama said opponents are stifling customer choice. And he noted that some Tea Party leaders were supporting pro-solar policies.

Obama’s speech to about 1,000 people at the National Clean Energy Summit 8.0 was the first leg of a climate tour that will culminate in a three-day Alaska trip next week. The president has made climate change the signature issue of his second-term agenda, and is highlighting the flooding, storms, drought, wildfires, polar ice melting and other effects of increasing global temperatures.

But in Las Vegas Monday, he struck an optimistic tone, echoing his campaign slogan of “Yes, we can.”

Obama said the growth in solar — which is 20 times bigger than it was in 2008, is “like evolving from the telegraph to the smartphone in less than a decade.”

“I’m here to give you hope, but not complacency,” he said.

Companies like Wal-Mart and Google were turning to solar and renewable energy “not because they’re tree-huggers,” he said, but because they’re cost cutters.”

Turning another phrase, he said, “Solar isn’t just for the green crowd anymore. It’s for the green eyeshade crowd, too.”