Electrical bills in all of Hawaii Electric Co.’s service areas bumped up in December due to higher fuel prices.

The bill for an Oahu household using 500 kilowatt-hours in December went up $1.28. The bill is $132.32, or 24.4 cents higher per kilowatt-hour. In November the bill was $131.04, or 24.2 cents per kilowatt-hour.

HECO spokesman Peter Rosegg said bills were up because of higher fuel prices and costs from independent power producers.

On Oahu half of the energy HECO uses is bought from eight independent power producers. The independent power producers include AES Hawaii, a coal-fired facility in Kapolei, and the Kahuku Wind facility on the North Shore.

The rate roller coaster continues as December marks the second straight month of increases following two months of minor reductions in electrical prices. Still, the price of electricity in Hawaii is double the average of electricity prices across the nation.

Hawaii residents paid an average of 27.84 cents a kilowatt-hour in September. The national average was 12.87 cents in the same month, according to the latest figures from the U.S. Energy Information Administration.

Hawaii has the highest electricity rates in the nation, largely due to the state’s use of imported oil for most of its power. According to the EIA, Hawaii has spent $5.4 billion on petroleum so far this year.

Other states use a mix of energy resources such as natural gas, hydroelectric power, coal or nuclear power.

In 2015 HECO’s energy mix was roughly 71.1 percent oil on Oahu. HECO imports oil primarily from Southeast Asia and the Middle East.

Neighbor island households had to dig even deeper for December.

The residential rate for Hawaii Electric Light Co. customers on Hawaii island was $4.69 higher this month. The average bill for a household using 500 kilowatt-hours on the Big Island is $164.41, or 30.6 cents per kilowatt-hour, up from $159.72.

Maui Electric Co. customers saw a nearly $4 increase.

The average bill for a Maui household using 500 kilowatt-hours is $139.41, or 26 cents per kilowatt-hour, up from $135.84 last month.

MECO customers on Molokai using 400 kilowatt-hours of electricity are paying an average of $135.75 with a rate of 31.5 cents a kilowatt-hour, up from $132.85 in November.

Lanai saw the greatest increase from last month, up $5.74.

Lanai residents using 400 kilowatt-hours of electricity on the island are paying 33.2 cents a kilowatt-hour, or $142.33, in December compared with $136.59 in November.

Bills on Lanai and Molokai are provided based on electrical use at 400 kilowatt-hours. This is due to lower energy use compared with Maui, Big Island and Oahu, HECO said.

HECO, MECO and HELCO monthly bills include the cost for kilowatt-hours used plus other charges.

The Kauai Island Utility Cooperative decreased its rate to 33.23 cents per kilowatt- hour in December, down from a rate of 33.43 cents in November.

But the bills were higher on Kauai, due to an increased customer service charge, up from $10.58 that KIUC used to charge members.

The typical bill for a household using 500 kilowatt-hours, including a $13.50 customer base charge, is $180.10, up from $177.73.