Britain’s largest-ever renewables auction is set to deliver record numbers of new solar and onshore wind projects, energy secretary Ed Miliband has announced.

Together with last month’s auction to build a raft of new offshore wind turbines, a record 201 projects have been approved this year, with a total generating capacity of around 14.7GW.

The government said that the latest rounds put the UK “on track for its 2030 clean power target” for low-carbon sources such as wind, solar and nuclear to produce at least as much electricity as the country consumes over the year.

Based on the average size of past developments, the solar projects could cover more than 40 square miles of mainly farmland – just under the size of the Manchester. However, the solar industry believes that modern panels’ improved efficiency should bring this down to around 36 square miles.

Prices of £72.24/MWh for the new onshore wind and £65.23/MWh for the new solar have been agreed with developers, both less than half of...