SHE Transmission, a subsidiary of SSE, said the decision to proceed with the plans followed a positive feedback from energy regulator Ofgem.
The upgrade includes installation of a twin sub-sea cable link from a new substation called Crossaig on the Kintyre peninsula to Hunterston on the Ayrshire coast.
Plans also include a new 13.5km section of tower line between the new substation at Crossaig and the existing substation at Carradale, which will largely follow the existing route.
After completion, the upgrade will supply an additional 150MW of grid capacity for renewable projects.
The investment is part of SHE Transmissions’ plans to invest about £5bn in its electricity network between 2013 and 2021.
SSE transmission director David Gardner said Ofgem’s announcement signals another significant step in the company’s plans to upgrade the transmission infrastructure throughout Scotland.
"Along with completion of key projects within our approved budget of £1.4bn, including good progress on Beauly Denny, this project demonstrates that we are gaining momentum on our capital expenditure programme which will connect significant amounts of renewable energy to the grid; contributing to energy security, economic growth and decarbonisation of electricity generation," Gardner added.
