In a power outage, what happens? Lights go dark, and electronic devices go quiet. The realization of the outage comes when you flip a light switch or plug in a phone to an outlet and nothing happens. But for Warren Kibbe of Chapel Hill, the lights remain on, the refrigerator stays cold, and the WiFi doesn’t go out.

“When we lose power, the batteries take over,” said Kibbe, chief for Translational Biomedical Informatics at the Duke Cancer Institute. “I don’t even notice when it takes over in some rooms.” That’s because Kibbe has 56 solar panels on his house and a lithium-ion battery that can store power the panels produce.

Lithium-ion batteries are one of the most common types of energy storage and can either be used in conjunction with an alternative energy source, like Kibbe’s home solar panels, or by themselves, fed by energy from the power grid.

Kibbe’s two Tesla Powerwall batteries — each of which stand about 3 feet tall, 2 feet wide and 1 foot deep — standy by ready if and when his local utility, Duke Energy, suffers an extended power cut. At that time Kibbe can flip a switch and send electrical energy from his batteries to power his kitchen, a heat pump and lights throughout his house. The batteries usually don’t recharge the Tesla car although they could in the event of an extended power cut.

“The batteries can store about half of what the solar panels can produce on a really bright day — about 45 kilowatt hours,” he said. (For reference, a kilowatt hour is the amount of energy equal to sustaining a thousand watts of power for an hour.)

High cost of lithium-ion home batteries

Although North Carolina is a leader in solar power, solar panels and batteries like Kibbe’s are far from commonplace. Starting prices for leading battery models like the Tesla Powerwall or the Generac PWRcell are several thousands of dollars, and that’s not including the battery installation or the cost of solar panels.

But according to Rui Shan, a graduate research assistant in environmental sciences and engineering at UNC Chapel Hill, several factors will make batteries more popular including falling prices, increasing climate awareness and increasing familiarity with energy storage technology.

“Costs are always declining,” Shan said. “We can foresee a future with everyone with a battery in their households.”

James Robinson, senior project development manager at Strata Solar, said although Strata works with the utilities side of energy storage, he knows the market for residential lithium-ion batteries is growing.

“The products sold on the market are very well-developed and fully commercialized,” Robinson said. “The market itself is still developing but close to mature.”

Robinson said right now, buying a home battery is usually less of an economic decision and done more for resiliency, which is the ability for the power grid to withstand disturbances or failures.

Kibbe said although his main motivation for getting solar panels was to be environmentally friendly, the main draw toward the batteries is their resiliency, such as providing power during outages, and doing so smoothly.

Shan said these batteries can provide power for four to six hours following an outage. Despite this benefit, the costs associated with batteries will not yet save consumers money.

Incentives for battery storage

To help with the financial costs of buying a battery, some government and utilities companies offer rates that incentivize battery storage, Robinson from Strata Solar said. But these mainly exist in metropolitan areas in New York and California, and they’re rare.

In Vermont, Robinson said Green Mountain Power is incentivizing home batteries to improve the grid for everyone. “They’re subsidizing energy storage in exchange for control of how it is used,” he said. “If you can get everyone in a city to discharge their battery during a heat wave, it would provide value in the aggregate.”

The thriving solar industry in North Carolina has led lawmakers to offer tax credits, rebates and other incentives  to consumers over the years, but the same cannot be said for battery storage.

Other types of storage, such as iron-sulfur and hydrogen batteries, are less developed and much more expensive, Shan said. Costs of batteries do go down over time. For example, the price of lithium-ion batteries has gone down by 97 percent since their introduction 30 years ago, according to OurWorldinData.org.

Lithium-ion home batteries may take several years to become more popular in North Carolina. But Shan said with time, as awareness of this technology grows among consumers and prices fall, North Carolina residents may find home energy storage an affordable option.