Combining energy storage with rooftop solar helps one Pearl City resident always keep the lights on as he cares for his mother.

Mark Ida, 53, installed an energy storage system used to work with his rooftop photovoltaic. The Energizr battery system stores the excess energy his PV system creates during the day to help power Ida’s home for up to one full day when the sun isn’t shining or when the electrical utility experiences problems with its grid.

Maui Solar Project has teamed up with Sacramento, Calif.-based JLM Energy Inc. to offer Hawaii residents the battery storage system with their rooftop solar panels.

The company’s first residential installation on Oahu was at Ida’s Salt Lake home in February.

Ida said he was looking for a way to keep the power on during outages as he cares for his mother, Elma Saida, 83.

"I’m a caregiver for my mom, and energy is super important to me," Ida said. "I’m a grid security customer. I protect my mom."

During a recent power failure, Ida said, the battery kicked in, and his mother’s bathroom lights, television set and electric hospital bed continued running without a hitch.

"She wasn’t even aware (of the blackout). What a good feeling for me," he said.

The typical solar system on Oahu does not work during a blackout even if the sun is shining. Solar systems need a signal from the grid, saying that the grid is working, before they can send power into a home or into the grid.

The Energizr, the energy storage unit Ida is using, offers 8.8 kilowatt-hours of energy. It can keep a rooftop solar system of up to 30 panels powering a resident’s home for about 24 hours, said Maui Solar Project President Josh Porter.

The battery system can serve as a backup during a power failure, and it can reduce the energy a PV home needs to purchase from the grid overnight or on cloudy days.

The cost of the energy storage module is $22,500. In some cases, tax credits can potentially bring that cost down, Porter said.

"You can still be grid-tied, but this will take over in the event that the grid goes down," Porter said. "What this does for people is it takes the concept of having energy security and energy autonomy out of fantasyland and into reality."

Porter said he gets a call every day from a homeowner wanting to get off the grid, or what he calls "grid defecting."

"This is the first compact, easily managed technology that approaches that," he said. Currently it would cost too much for most homeowners to add enough battery systems to disconnect completely from the grid, but that day may not be too far off, Porter said.

Because of advances in battery technology, much of it fueled by electric cars, it won’t be long until having a battery system in your home will be "as common as a refrigerator."

Gov. David Ige said last week that energy storage is critical if Hawaii is to move toward a goal of 100 percent renewable energy use.

"The thing about renewable energy today is about being able to store energy when we are generating and able to generate it to be able to deliver it at the time of the demand," Ige said.

Most people will be able to meet their critical loads for a full day when connecting one Energizr module to their photovoltaic system, Porter said.

"Right now we have a house set up with two refrigerators, 15 lights, an 80-inch television that can run all day on PV and definitely run all night until the next day for the PV to come on and replenish," Porter said.

The module, a lot like an appliance, is 16 inches wide by 90 inches tall by 9 inches deep.

The size is the most compelling aspect of the piece, said Porter.

"It’s very compact, far more compact than anything that has been available before," he said.

"I think we are going to see a lot of people go down that road," Porter said.

Residents who install an energy storage system at the same time they add PV could be eligible for renewable-energy tax credits. There is a 30 percent federal tax credit available to Hawaiian Electric Co. customers who install solar systems before Dec. 31, 2016. Hawaii has a state tax credit of 35 percent of the cost for a solar power system installation, up to $5,000 per system.