The British billionaire who rescued the Whyalla steelworks is calling on government to provide more "support" for big companies that want to invest in renewable energy.

Sanjeev Gupta says he wants a "fast track easy package" that would help business fund rooftop solar.

The long-running uncertainty around national energy policy means many major firms have avoided long-term renewable projects like large-scale rooftop solar installations.

But some, including Coca Cola Amatil and Woolworths, pushing ahead anyway and installing thousands of panels — they say it's just too risky "to do nothing".