Record summer heat drives increase in electricity demand

  • As temps soared in July, usage rose 12%

  • Customers, especially those with rooftop solar, see higher bills

  • Tips available for reducing energy use

Release Date: 9/23/2019

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HONOLULU, Sept. 23, 2019 – Intense summer heat showed up earlier in 2019 and is sticking around, driving increased demand for electricity to run air conditioners.

Customers of Hawaiian Electric, Maui Electric and Hawaii Electric Light are seeing that demand reflected in higher bills, including those for customers with private rooftop solar, and the companies are urging everyone to use energy wisely.

Electricity demand began rising noticeably in May, about a month earlier than usual. From May through August, residential use was up on all islands served by the Hawaiian Electric Companies except Hawaii Island, compared to the same four months in 2018.

Over the four-month summer period, Oahu and Maui residential usage increased 5 percent; Lanai, 6 percent; Molokai, 2 percent. Hawaii Island residential usage decreased by 1 percent.

Usage was highest in July, when a number of local temperature records were set.

Change in usage from July 2018 July 2018 bill July 2019 bill
Oahu 14% $157 $183
Maui 13% $200 $224
Hawaii 2% $181 $182
Lanai 10% $179 $203
Molokai 7% $134 $144
All 12% $168 $189

Most of that increase can be attributed to air conditioning. As trade winds have slackened and temperatures have risen, the percentage of homes with at least one air conditioner has increased.

Homes with A/C 1970 2014 2019
Oahu 14% 50% 68%
Maui, Molokai, Lanai 2% 44% 53%
Hawaii 2% 19% 32%

Electric usage by customers with private rooftop solar is also up significantly.

For example, in Ewa Beach and Kapolei in June, residential customers with rooftop solar used 37 percent more electricity from the grid than in June 2018, and in July it was 57 percent more. For solar customers who get credits for the excess electricity their systems send to the grid, the increased usage will mean they’re using up their credits faster and generating little excess, potentially resulting in higher bills this fall.

Also, on hot days with high humidity and overcast skies, most rooftop solar is producing less electricity, requiring customers to draw more from the grid. Customers should make sure their panels are clean and that inverters and other equipment are working properly. For questions about your rooftop system’s production, check your system’s online portal or contact your contractor.

“With the record-setting hot weather, some customers with rooftop solar are leaving their air conditioning on all day or are running it at a colder setting and are surprised when they get a higher than normal bill,” said Shelee Kimura, senior vice president for customer service. “We want all of our customers, including those with solar, to continue to use electricity efficiently and keep their bills as low as possible.”

Nearly all appliances use more energy and work harder during hot weather, especially air conditioners, refrigerators and freezers. Clean or change filters and air intakes. Refrain from running air conditioning when no one is home and set the thermostat to the warmest comfortable setting – you’ll save about 3 percent on your energy bill for each 1 degree you raise your temperature setting, according to Consumer Reports.

For more tips to stay cool at home and work, go to Find more tips and rebates for energy efficient appliances at