Renewable energy investment hit a new high in 2017, but analysts have warned that investment could collapse under the National Energy Guarantee.

Bloomberg New Energy Finance (BNEF) says there has been a 150 per cent increase in Australia's renewable energy investment last year, to a record $US9 billion.

Investment was driven up by generators pushing to meet the Federal Government's large-scale renewable energy target (RET) of 33,000 gigawatt-hours of generation by 2020.

“The renewable energy target has actually become quite an ambitious target over the next few years because we had this big pause of investment in the Abbott years, when policy was extremely uncertain,” BNEF's Australian head Kobad Bhavnagri has told the ABC.

“The industry had to race to mobilise and catch up. That's why we had to invest a huge amount last year and the industry's shown that it's perfectly capable of doing that.”

But Mr Bhavnagri says the new National Energy Guarantee (NEG) policy may not be ambitious enough to continue driving investment.

“After 2020 when the current renewable energy target is met, investment under federal policies would likely fall off a cliff, because the national energy guarantee, as currently floated by the Federal Government, would require very little effort to achieve,” he said.

The NEG seeks to reduce emissions to 26-28 per cent below 2005 levels by 2030.

“A deeper emissions reduction target, or more action by state governments, will be required to sustain investment around the historic average,” said Mr Bhavnagri.