The funding boost comes after Labour ministers also announced sweeping changes to the planning system aimed at speeding up construction of wind turbines, solar farms and electricity pylons across the country.
Labour has pledged to make the electricity system net zero by 2030 and transform the UK into a “clean energy superpower”.
Energy UK, the trade body, said the move was “a big step in the right direction and another welcome demonstration of the Government’s ambitions”.
Dan McGrail, the chief executive of RenewableUK, said: “These new wind and solar farms will improve our energy security, drive economic growth, support thousands of new green jobs and ensure we continue to create a lowest-cost electricity system for bill payers.
“This builds on a series of positive announcements from the Government which are increasing investor confidence in the UK, including ending the ban on onshore wind in England and approving new large-scale solar farms.”
Last year, developers complained the maximum £44 per megawatt hour (MWh) strike price for offshore wind schemes was too low.
Soon afterwards, Rishi Sunak’s government relented and increased the cap to £73 per MWh – equivalent to £100 today.
As experts warned that Britain must make up for lost ground to hit its ambitious renewable energy targets, Mr Miliband said he had also increased the offshore wind budget this year by £300m to “send a strong signal to industry to invest in UK waters”.
The new £1.1bn budget is more than all previous offshore wind allocations combined, the Labour Government said.
There will also be £65m more for “established” technologies such as onshore wind and solar, taking that budget to £185m, as well as £270m for “emerging technologies” such as floating offshore wind and tidal – an increase of £165m.