Money. There are a number of reasons solar power hasn’t been developed on a massive scale around the globe. Some say it just hasn’t had the support it needs in mainstream media. Others say transmission or energy policy is to blame. But in the end, it’s all about that one thing – money.

Industry experts spoke about what barriers they saw to greater solar and other renewable energy development at the Renewable Energy Gala hosted in Denver, Colo. earlier this week.

“We need a comprehensive policy from a bold political leadership that we just completely lack right now,” said J.W. Postal, who helped to found Mainstreet Power, a Boulder, Colo.-based company that finances large-scale solar projects.

He noted that states are trying to incentivize solar on their own, creating niche programs. But it’s not enough, he said, noting that one utility in New Mexico offered an incentive for four megawatts of new solar development and exhausted it within six minutes of the launch of the program.

“In the end, it all comes down to what you’re company is doing, J.W.,” said Rick LeBlanc, CEO of SkyFuel, a concentrated solar company.

Postal founded Mainstreet Power in 2008 after he sold his financial advising business. “Basically we were running into the burning building as everyone else was running out,” Postal said of going into the world of high finance just as the economy was tanking.

“I was always trying to figure out how I could do financial and green stuff together,” he said.

Mainstreet Power has worked primarily with nonprofit organizations and schools. The company has leveraged tax incentives to build solar installations and then formed a power purchase agreement with the host site so that the host pays no upfront costs, just a fixed rate for 20 years or for seven with a plan to purchase the system after that period. “The secret to our success has been our banking relationships,” Postal said.

And now that the company is solidly formed and has those banking relationships, it’s branching into larger-scale financing for solar projects around the globe, including some in Europe Asia and India, Postal said.

Because solar and other renewable energy projects have high up-front costs, getting loans and being able to leverage future tax breaks are key, which means tax incentives for solar are key.