Residential electrical rates fell on Oahu in May from the previous month but rose on all other islands, the state’s two power companies reported.

The movement in prices was the opposite of April when rates rose on Oahu and fell everywhere else.

On Oahu the bill for a typical household using 600 kilowatt-hours of electricity a month will be $210.28 in May, down from $212.05 in April, according to Hawaiian Electric Co. The May rate is 33.5 cents a kilowatt-hour, down from 33.8 cents a kilowatt-hour in April.

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 Co. customers are paying 37.3 cents a kilowatt-hour, up from 36.5 cents last month. The bill for a household using 600 kilowatt-hours of electricity is $232.25, up from $227.42 in April.

Hawaii island’s residential rate is 39.8 cents a kilowatt-hour, up from 39.1 cents a kilowatt-hour in April. The bill for a household using 600 kilowatt-hours of electricity is $249.46, up from $245.36.

On Kauai the rate is 42.7 cents a kilowatt-hour, up from 41.9 cents in April. The bill for a household using 600 kilowatt-hours of electricity is $256.20, up from $251.40.

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. Roughly 80 percent of the electricity consumed in Hawaii is generated by burning oil, the highest percentage of any state. The next-highest state is Alaska at about 14 percent, according to the U.S. Energy Information Administration.

The Hawaii 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.

The state’s two electrical utilities last year burned 7.21 million barrels of oil, compared with 7.61 barrels of oil in 2012, according to the state.

LIGHTING UP

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

Note: The average monthly kilowatt-hour usage varies by islands, and 600 kwh, which is typical for Oahu, is used for all islands for comparative purposes.

Source: Hawaiian Electric Co., Kauai Island Utility Cooperative