A 25-megawatt battery-based energy storage system has been connected to the electricity grid to store surplus power from wind and solar plants.
Located in a field near Taunton, it works by buying and storing electricity when it is cheap and then selling it at peak demand for a profit.
It also helps the National Grid balance the demand on the supply network.
South Somerset District Council is hoping to make a return of up to 14% on its investment
The money made will be put back into supporting frontline services.
At present there are times when more electricity is generated than needed so part of this surplus is “banked” and sold back for a higher price on energy markets.
Councillor Sarah Dyke said in a climate emergency, green energy sites “make a powerful statement” about its commitment to reducing in carbon emissions by 2030.
Read more: BBC