With nearly 57,000 solar energy systems connected to Oahu’s electricity grid, a normal morning in Hawaiian Electric Co.’s control room today looks a lot different from how it did in 2010.

Dave DeViney, supervisor of load dispatch at HECO, and other operators respond to alarms almost every 30 minutes on some days as cloud coverage or other fluctuations in weather change the electrical system’s frequency — the second-­by-second balance between the amount of energy Oahu’s residents are using and the total generation HECO’s system is providing.

“If the frequency drops too low … and we can’t control it, our generators start shutting down to prevent severe damage,” DeViney said. “The same thing happens if the frequency goes too high. … We start shutting down to prevent damage.”

Before 2011 the utility would ramp up oil-fired plants to support Oahu residents’ energy use in the early morning hours, gradually increase generation from 8 a.m. to 4:30 p.m. and eventually provide enough energy to meet peak use at 7 p.m. in the dinner hours. Then customer demand would reduce at night.

Currently, DeViney and his team have to constantly adjust generation output during the day as weather changes. When the island reaches its peak evening energy use, the controllers have to dramatically ramp up the fossil-fuel generation to compensate for the sun no longer providing energy.

HECO’s challenge is how to weave renewable energy into the grid without causing large swings in the frequency. Right now renewables make up 19.4 percent of Oahu’s energy mix, and by law the utility has to increase that to 100 percent renewable by 2045.

One of the latest solutions HECO is looking at is called the “smart-export” program, which would only allow new solar systems to send energy into the grid when HECO needs it most, primarily evening and morning hours. This means the “smart-export” solar owners would have to store solar power, usually in batteries, before sending it into the grid.

Owners of the “smart-grid” systems would be credited for the power they provide, but how much they would get is a point of contention.

Members of the solar industry said in an August filing with the state Public Utilities Commission that solar system owners in the smart-export program should be credited 18 cents a kilowatt-hour for the energy they export from 4 to 10 p.m. — when the customers on the utility’s grid demand the most energy. Solar system owners would also be credited 16.5 cents a kilowatt-­hour from 6 a.m. to 9 a.m.

HECO’s original and most popular solar program, net energy metering, pays solar owners the full retail rate for power sent into the grid. In August that rate was 26 cents a kilowatt-hour. The net energy metering program stopped accepting new customers in October 2015.

HECO is arguing for a “smart-export” payment formula that would likely result in solar owners getting paid roughly 10 cents a kilowatt-hour.

The solar industry says the higher rate is needed to encourage homeowners and others to invest in a solar system with a battery.

“You create a market, and you can have battery systems provide power back to the grid when it is needed,” said Robert Harris, director of public policy for Sunrun Inc., a San Francisco-based solar company.

Eventually the state Public Utilities Commission will decide whether to approve the “smart-grid” program and what rate will be paid to solar owners.

What is of greater concern to some in the solar industry is HECO’s proposal to have the ability to shut off the “smart-grid” solar systems when needed.

HECO said in its filing with the PUC that it needs the power to shut off solar systems “because of hard lessons learned” while trying to add fluctuating renewable energy to a grid that needs consistent generation.

HECO has gotten pushback from the solar industry because the additional control could lead to customers’ photovoltaic systems being completely shut off even when they are not sending power to the grid.

“Over the past two months or so, we have had nonstop meetings where the point of difference boiled down to this idea of control and monitoring,” Harris said, noting that during times the utility turned off a customer’s solar energy system, it would force the solar owner to buy energy from the utility instead of relying on its PV system to power its appliances. “You don’t just simply say, ‘We’re going to make you turn on all of your appliances and buy power from us.’”

The PUC is expected to make a decision on whether to move forward with the smart-export program this fall.

“The hope is that there will be some kind of smart-export (rate) ready to launch soon after Oct. 21,” said Marco Mangelsdorf, president of Hilo-based ProVision Solar. “I’m thinking that the best case-scenario is that we would have (smart-export) forms ready sometime in late November.”

HECO spokeswoman Shannon Tangonan said the smart-export program can help fix some of the utility’s control issues, but the utility is also looking at other programs such as a solar and wind forecasting tool.

“We can’t just count on one program to fix this,” Tangonan said. “We’re constantly looking at new technology.”