Residential customers on Oahu will be paying roughly $6 more this month for their electricity bill than they did in May.

The combination of an annual rate adjustment that went into effect this month and higher fuel prices incurred by Hawaiian Electric Co. will increase the bill on Oahu for a typical household using 600 kilowatt-hours of electricity a month to $216.08 from $210.28 in the previous month, Hawaiian Electric Co. said Thursday.

The bulk of the Oahu increase — $4.89 for a typical household — is the result of the state Public Utilities Commission approving May 30 an annual "sales decoupling tariff" adjustment requested by Hawaiian Electric Co., Hawaii Electric Light Co. on Hawaii island and Maui Electric Co.

That yearly decoupling adjustment is designed to compensate the utility for increased capital expenditures and declines in sales over the past year.

Decoupling, which began in 2011, is structured to encourage the development of renewable energy and energy conservation by eliminating the economic incentive on the part of the utility to sell more electricity. Decoupling, or breaking the link between sales and total electric revenue, essentially guarantees utilities enough revenue to cover their fixed costs even if their electricity sales decline.

"We are continuing to work on lowering customers’ bills by developing more renewable energy, increasing energy efficiency and pursuing liquefied natural gas as a cheaper, cleaner alternative to expensive imported oil," Hawaiian Electric spokesman Darren Pai said.

On Oahu the June rate rose to 34.5 cents a kilowatt-hour from 33.5 cents a kilowatt-hour in May.

HECO, its sister utilities in Hawaii and Maui counties, and the Kauai Island Utility Cooperative adjust their rates monthly to reflect changes in their fuel costs and the prices they pay for electricity purchased from independent power producers.

Maui Electric customers this month are paying 37.6 cents a kilowatt-hour, up from 37.3 cents last month. The bill for a household using 600 kilowatt-hours of electricity is $234.15, up from $232.25 in May.

Hawaii island’s residential rate is 40.0 cents a kilowatt-hour, up from 39.8 cents a kilowatt-hour in May.

The bill for a household using 600 kilowatt-hours of electricity is $255.62, up from $249.46.

On Kauai the rate is 42.2 cents a kilowatt-hour, down from 42.7 cents a kilowatt-hour in May. The bill for a household using 600 kilowatt-hours of electricity is $253.20, down from $256.20.

Average monthly kilowatt-hour usage varies by island, but the 600 kwh number is used for comparative purposes.

The price of electricity in Hawaii is more than three times the national average in large part because of the high cost of fuel oil used for power generation.

Hawaii residents paid an average of 38.5 cents a kilowatt-hour for electricity in March compared with the national average of 12.3 cents a kilowatt-hour, according to the latest data available from the U.S. Energy Information Administration.

The Hawai’i Clean Energy Initiative, adopted by the state in 2008, set a goal that 40 percent of the state’s electricity will be generated from renewable resources by 2030.

At the end of 2013, 18 percent of Hawaiian Electric’s sales were made using renewable sources, surpassing the company’s goal of 15 percent for 2014, HECO said.

LIGHTING UP
Statewide utility costs in June for a household using 600 kilowatt-hours and the percentage change from the previous month: