The new report from the Electricity Networks Strategy Group shows that up to 1,000 kilometres of new cabling will be required to ensure all the country's renewable and non-renewable power stations are connected to the grid.
In Scotland alone some 11.4GW of renewable energy facilities are expected to be online by 2020.
Alistair Buchanan, the chief executive of the gas and electricity watchdog Ofgem, said: "Getting the right electricity infrastructure in place so more renewable generators can connect is critical if the UK is to meet challenging new renewable targets."
Gordon Brown is expected to outline a vision for Britain's low carbon economy which will create an estimated 400,000 new green jobs.
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