The Maine Public Utilities Commission said Tuesday it has accepted a bid for energy supply that was 3 percent lower than last year. The rate is tied to the low cost of domestic natural gas used to generate much of New England’s electricity.

Medium-sized business customers who use the standard offer will see an annual average drop of 11 percent compared to last year. The standard offer is the default rate for customers who don’t sign contracts with a competitive energy supplier, and it covers about 70 percent of Central Maine Power’s home customers.