The UK dropped to 13th place in G20 rankings last year for its investment in clean energy, the Pew Environment Group says.
The Pew Environment Group study showed that Britain slid from third place among the world’s leading economies for investment in green energy, efficiency and low-carbon technology and services in 2009 to 13th place in 2010.
Total global investment in renewables and energy efficiency bounced back after the economic crisis, rising 30 per cent last year on 2009's figure to a record £152 billion.
China leads the way in green energy investment for the 2nd year running, with £34 billion. Germany and the US were a respective second and third.
The UK’s worsening performance came despite Europe as a whole being the biggest recipient for investment, with finance totalling £59 billion.
Many EU countries, such as Italy, Spain and France, now invest more in renewables than the UK does.
UK investment dropped by 70 per cent from £6.9 billion in 2009 to £2 billion last year, of which 60 per cent went to wind power.
“Investment levels in 2009 were driven by large-volume finance for offshore wind energy and the Government's commitment to strong action on climate change.
“But 2010 brought a new Government to Great Britain and investors appear to believe that there is a high level of uncertainty about the direction of clean energy policymaking in the country,” the report said.
The coalition Government has pledged to be the “greenest ever”.
But it has recently announced reductions in the incentives larger-scale solar farms can receive under the feed-in tariffs scheme for small-scale renewables, which have spurred investment in Germany and Italy.
In the Budget last week Chancellor George Osborne announced the Green Investment Bank. This is designed to promote renewables and clean technology but will not be able to borrow until 2015, which critics say will undermine its ability to drive private investment in the sector.
Friends of the Earth energy campaigner Tony Bosworth said the UK had “world-class renewable energy potential - we should be international leaders in green power investment, not plummeting towards the bottom of the league”.
“Offshore renewable energy alone could meet all the UK’s electricity needs and more - and create tens of thousands of jobs.
“It’s little surprise that investors are reluctant to put money into renewable power. Ministers have created a climate of uncertainty over their commitment to clean, safe and low-carbon sources of energy.
“Robbing the Green Investment Bank of its ability to borrow money to invest in green power and plans to cut funding for solar electricity schemes are yet further Government blows to a fledgling industry that could help slash UK emissions and soaring fuel bills.”
A spokesman for the Department of Energy and Climate Change (DECC) said the UK is an “attractive place to invest in clean energy and the prospects for massive growth in this sector are strong”.
“We’re already leading the world in offshore wind, with more installed capacity than any other country, further construction under way, and big-name turbine manufacturers considering locating here.
“The coalition’s reforms of the electricity market, the Green Investment Bank and funding for CCS demonstrations will make the UK the destination of choice for global clean energy investment.”