National Grid has secured an extra 3.58GW of electricity to cover potential demand during winter 16/17.
The operator awarded 12 Supplemental Balancing Reserve (SBR) contracts worth £122.4 million.
A total of 18 tenders from seven companies signed up.
They represent 11 power plants offering 6.4GW of capacity of which 5.8GW is not currently available in the market, according to National Grid.
SSE, Centrica and ENGIE were among the winners.
Earlier this year the grid operator said electricity margins in the UK will continue to be “tight but manageable” this winter.