Residential electricity prices in the US averaged at 12.3 cents per kilowatt hour (KWh) in the first half of 2014, according to the Energy Information Administration (EIA).

It increased by 3.2% this year compared to the same period in 2013 – the highest year-over-year growth for the first six months of the year since 2009.

The largest price rise was seen in New England, averaging 11.8%, with the main driver being the sharp rise in wholesale power prices, the EIA said.

The first six months of 2014 saw day-ahead wholesale prices at $93MWh on average – 45% higher than the same period last year, it added.

The EIA also suggested prices have been rising in part because power companies have been spending more on the transmission infrastructure for delivering electricity to customers.