The president of a company called Renewable Funding developed a scheme to help finance property owners’ solar power and energy-efficiency projects through low-interest municipal bonds, repaid over 20 years through a markup on the project owner’s property tax bill. The script has flipped, with Renewable Funding securing financing — $12.2 million — from a group of venture capital firms. Some of the venture capital firms’ other investments in solar and energy-efficiency startups could potentially benefit from a rapid expansion of Renewable Energy’s footprint, putting green retrofits within reach for a broader base of customers.