Investments by the government's $10 billion clean energy fund are growing at an "almost exponential" rate but growth could shudder to a halt if the industry's post-2020 policy is not settled, according to the agency's new head, Ian Learmonth.

Mr Learmonth, who took on the role of chief executive of the Clean Energy Finance Corp, said the fund had about 50 transactions in the pipeline worth about $4 billion of its own funds. Based on previous years' results, partners joining the CEFC would lift the total investment value to $10 billion.

In the year to June 30, the CEFC committed to 35 projects in wind, solar, storage and energy efficiency projects worth almost $2.1 billion, more than double the previous year's tally and close to five times the size of its first-year investments in 2014-15.

"We feel like we've gone mainstream these days," Mr Learmonth told Fairfax Media on the sidelines of the Clean Energy Summit in Sydney, adding that Prime Minister Malcolm Turnbull and Environment and Energy Minister Josh Frydenberg had trumpeted the fund's activities. "I don't have any concerns about the political issues around the organisation."