In the early 1990s, he had enough foresight about the porn industry’s online potential to register the domain Sex.com. Later, he moved into online dating, founding dating site Match.com.

These days, however, the San Francisco-based serial founder is all about solar. Clean Power Finance, which Kremen founded in 2006 several months after selling Sex.com for a reported $14 million, last week closed a $6.9 million Series A funding round. The round was co-led by venture firms Claremont Creek Ventures and Clean Pacific Ventures. Sand Hill Angels, an angel investment group in the San Francisco Bay Area, and Kremen also participated.

“It feels a lot cleaner,” Kremen said of his new industry, compared to owning the rights to Sex.com. Kremen said the 12-person company will use the funds to further develop its software platform for solar installation financing and to expand into other energy sectors.

Kremen, Clean Power’s chairman, estimated that currently about 1,000 installers of solar power equipment nationwide are using Clean Power Finance’s system, which includes tools to generate quotes, estimate energy bill savings, locate third-party financing, and apply for government rebates.

Clean Power is one of several startups offering financing applications for solar installations. San Jose, Calif.-based OnGrid Solar, develops software and provides tools for estimating energy savings from solar panels.

Others, including venture-backed Solar City and SunRun, provide both financing and oversight of solar installations. Foster City, Calif.-based SolarCity previously raised $50 million in venture funding from Draper Fisher Jurvetson, J.P. Morgan Partners and DBL Investors. San Francisco-based SunRun raised $30 million from Accel Partners and Foundation Capital.

For Clean Power investors, a key draw was that its applications are suited to a broad range of installers, said Claremont Creek Managing Director Nat Goldhaber, who has joined the board of directors at Clean Power, along with Jeff Barnes from Clean Pacific Ventures.

“What interested us was the degree to which they had created a tool for solar installers who were small, medium, or some of the larger installers,” said Goldhaber, who notes that currently small-scale installation businesses make up a sizeable share of the market.

For the Oakland, Calif.-based venture firm, Clean Power is one of two cleantech-related deals announced in the past week. Claremont also led a $2.5 million financing round for EcoFactor, a residential energy management service. Goldhaber says the system can potentially cut heating and cooling costs by about 20 percent, in large part by operating more during times when cost of power is lower.

Looking ahead, Goldhaber says Claremont is planning to make more cleantech investments, making the sector a key focus of its early-stage fund, with a particular focus on energy-efficiency plays.