Billionaire backers of a renewable energy mega-project to pipe solar power from Australia to Singapore claimed a key breakthrough as Indonesia gave its blessing to plans to run the world’s longest high-voltage cable through its waters.

Sun Cable, the company behind the Australia-Asia PowerLink, said Indonesian government approval is crucial to its A$30bn ($22bn) plan to export power from up to 20GW of solar PV via a 4,200km HVDC link to Singapore.