The Department for Energy and Climate Change says it has "needed to drive through reforms to secure investment in new generation to keep the lights on in the years and decades ahead" after suggestions it may have cost consumers by awarding eight renewables contracts too early.
A spokesperson said the National Audit Office's report recognises that the early deals were "designed to offer better value to bill-payers" by reassuring investors.
"Without that investment, projects would have been unable to go ahead or been significantly delayed - putting our future energy security at risk."
More top news
Billy Connolly has revealed how his close friend Robin Williams rang his to say goodbye just days before taking his own life.
The anti-war President is now in combat in two Middle Eastern countries.
Prince Harry received a great big hug from four-year-old Carson Hartley.