Financial planners should be confident the clean technology sector is a viable long-term opportunity after US based investment in the sector rose 55 per cent to more than $2.4 billion over a year, according to CVC Sustainable Investments.

Sean Wiles, CVC Sustainable Investments investment manager, said a record level of venture capital investment in US based clean technology companies occurred in the third quarter of this year.

Wiles said the sector received a boost from the US government's $700 billion Housing and Recovery Act package that provided tax concessions for wind energy, geothermal and biomass projects.

In addition, he cited comments from Rajendra Pachuari, head of the Intergovernmental Panel on Climate Change, that financial institutions and other companies worldwide would pursue sustainable development when markets settle.

"The key issues that brought clean technology companies to prominence in the first place - namely energy security and climate change - are still as relevant today as ever," said Wiles.

Wiles said the firm's CVC Sustainable Investments fund achieve an average gross return in excess of 20 per cent across all realised investments since inception.