Ian Simm, chief executive of Impax Asset Management, which has almost £2bn of assets under management, said it would like to invest in UK wind farms - but the policy framework was currently too complex and unclear. "We are waiting to see what the landscape looks like," he said.
The Energy Bill, intended to drive £110bn investment in new low-carbon power to keep the lights on this decade, was introduced to Parliament this month [DEC] but is unlikely to gain Royal Assent until the end of next year.
Impax has a private equity investment arm specialising in funding the construction of renewable energy projects but currently does not invest in the UK.
"We would be very keen to jump into the UK once the Bill has been sorted out. But the situation is currently so complex that it is going to take several years to work out what the market looks like," Mr Simm told The Daily Telegraph.
"The detail is going to be in the secondary legislation and it's the detail that will determine whether lenders are willing to lend to projects."