New England's wholesale electricity prices last year fell to their lowest level since 2003, according to grid operator ISO New England.
Mild weather and low natural gas prices were both reasons for the low prices, as roughly half of New England's electricity comes from gas-fired plants.
Natural gas averaged $3.09 per million British thermal units last year, down from $4.64 in 2015 and also the lowest since at least 2003.
The average wholesale electricity price last year was $28.94 per megawatt hour, down from $41 in 2015.
Wholesale prices are only a piece of what ratepayers see on their bills. Retail prices also include transmission, distribution and other charges.
The $28.94-per-megawatt-hour wholesale price is equivalent to 2.9 cents per kilowatt hour, which is far less than the 16.7-per-kilowatt-hour retail rate Connecticut ratepayers paid in December, according to the most recent data available from the federal Energy Information Administration.
In addition, retail prices often lag behind trends in wholesale prices because rates are approved by state regulators, usually over six-month intervals, while wholesale prices change in real time, ISO NE said.