Investment in renewable energy companies reached $100 billion last year, driven by high oil prices and government incentives, according to a UN report.
The annual Global Trends in Sustainable Energy Investment report said that $30 billion of that total was due to mergers and acquisitions led by investment banks including JP Morgan and Goldman Sachs.
"[Renewable Energy] is now a mainstream commercial interest to investors and bankers alike," Eric Usher, Head of the Energy Finance Unit at the UN.
As a result, IPOs are on the rise again, led by the emergence of numerous solar firms, after several quiet years following the dot-com boom.
Usher said the report proves beyond a doubt that renewable energy is not a "fringe interest of environmentalists."
"The finance community has been investing at levels that imply disruptive change is now inevitable in the energy sector," he said.