1. Making $1,200 by Selling Electricity: What's the Secret?
A home in Texas, United States. A settlement screen sent by the power company reads: "You're getting paid for your solar!" It shows $123 this month and $1,200 so far. This household does not just buy and use electricity; it earns money by selling it. The secret is this box—a suitcase-sized container that transformed this house. But isn't it curious? South Korea is a global battery powerhouse, yet why don't we have something like this at our homes? We traveled to Texas to find the answer. Meet the homeowner, Craig Kincaid. A year and a half ago, he installed 50 solar panels on his roof and brought four Energy Storage System (ESS) batteries into his garage to store power. The investment cost around 50 million won (approx. $37,000), but the results were undeniable. Electricity bills that used to range between $400 and $500 a month—over 600,000 won—have dropped to just $20 to $30, or around 30,000 to 40,000 won. Here is why he spent a considerable sum.
[Craig Kincaid / Home with ESS installation: "I wanted to have emergency backup power for my wife and daughter at home, in case the air conditioning goes out in the summer or the heating is cut off in the winter."]
Texas experiences everything from tornadoes and hurricanes to winter freezes, making blackouts frequent. Yet, even when the entire neighborhood goes dark, this house stays powered.
[Craig Kincaid / Home with ESS installation: "On the day of the World Cup final, the entire neighborhood had a blackout. We had many guests over, but thanks to the battery, our house was able to watch the match all together to the end."]
That was possible because the electricity generated by the rooftop during the day was stored in these batteries. Moreover, all of this can be monitored on a smartphone. It displays in real time how much electricity the roof panels are generating, how full the batteries are, and whether electricity is being bought or sold at that very moment. On sunny days, surplus electricity is sold to the power utility. Under the rate plan Kincaid subscribed to, power sold is credited at the exact purchase price and deducted from the bill. That is how he earned the aforementioned
$1,200
.
2. A 'Refrigerator' That Charges When Cheap and Discharges When Expensive
This raises a question: Can installing only batteries without solar panels also be profitable? The CEO of a residential battery company in Texas says he keeps batteries at home without solar panels, charging them when electricity is cheap and discharging them when rates peak. It functions like a refrigerator where you buy food when it is cheap, store it, and consume it when prices rise. The price difference in electricity turns into profit. Furthermore, the cost of this "refrigerator" itself has dropped significantly. The secret lies in the shift in battery materials. In the past, expensive metals such as nickel and cobalt were used. Today, the mainstream choice is lithium iron phosphate (LFP) batteries. Iron and phosphate are abundant and inexpensive materials. Although their energy storage density is somewhat lower, that is hardly a drawback for storage units set up next to homes or power plants. In return, they are cheaper and pose a relatively lower fire risk. Korean battery manufacturers are also transitioning to LFP, and a Korean company supplies the battery maker used in Kincaid's home. However, there is a twist in this market.
[Bryan Pascoe / CEO of Signature Solar: "In the past, there were many states where you could resell surplus electricity, but as regulations changed, fewer places allow it. That is why battery demand is surging. Instead of selling it, you store it and use it yourself."]
Solar power is abundant during the day, but consumption peaks in the evening. If you cannot sell it, it goes to waste, so the solution is to store and use it. If you can sell it, you make money; if you cannot, you save money by storing it—either way, it is profitable. And this profitable business model is not confined to residential homes. This is the Arizona desert.
[This is a massive power generation complex 22 times the size of Yeouido. Eight out of ten new power facilities built in the U.S. consist of such solar and battery installations.]
One of the largest hybrid power complexes in the United States is being constructed here. The batteries installed on-site are also manufactured by a Korean company at its U.S. plant. The way this complex operates is identical to that Texas home: storing energy during the day and discharging it during peak demand hours, differing only in scale.
[The electricity generated in the desert right now is stored in these batteries and sold all the way to California in the evening.]
3. Silicon Valley of the Desert: Electricity Becomes Urban Competitiveness
Power plants are not the only places in need of batteries. A two-hour drive away lies Phoenix, Arizona. Emerging as the Silicon Valley of the desert, the city is attracting TSMC semiconductor fabs, Korean battery plants, and AI data centers. Here is what the city official in charge of business attraction had to say.
[Ryan Touhill / Community and Economic Development Director, City of Phoenix: "To continue expanding our manufacturing base and support global companies making the semiconductor chips of the future, power capacity to back that up is absolutely essential."]
Where does that power come from? In this region, the answer lies in the sky, with blazing sunshine for over 300 days a year.
[Christine Mackay / President and CEO of Greater Phoenix Economic Council (GPEC): "Arizona's battery and energy industry is growing explosively. In Arizona, where the sun shines 340 days a year, we can store that energy and use it when needed. This growth is not a temporary boom, but will continue to expand."]
Electricity has become a city's competitive edge. Operating a single large data center consumes as much power as an entire mid-sized city. The prompts you send to ChatGPT are processed in places like these. While building a conventional power plant takes 5 to 10 years, a data center can be erected in just 1 to 2 years. This creates a gap where power supply struggles to keep pace with demand—a gap that batteries are stepping in to fill.
[Tristan Doherty / Product Strategy Lead at LG Energy Solution Vertech: "Data centers are the new heavy industry of modern times. They place enormous demand on the local grid. ESS is how we stably connect this demand to the power grid."]
As a result, the market has exploded. ESS battery shipments in the first half of this year increased by 71% compared to the first half of last year.
4. Why Doesn't South Korea, a 'Battery Powerhouse,' Have This at Home?
Why don't homes in South Korea—a nation renowned for manufacturing top-tier batteries—have these systems? Searching for the answer revealed an interesting fact: South Korea does have giant electricity storage facilities. Pumped-storage hydroelectric power plants, which pump water up to a mountain reservoir and drop it to generate electricity, essentially serve as the nation's primary storage devices. However, this warehouse functions differently from that Texas home. It balances electricity supply and demand by pumping water when power is surplus and releasing it when needed. Yet, it is not structured for private operators to freely store and sell power based on fluctuating electricity prices. In other words, it is not that storage devices are lacking, but rather that the market mechanisms to properly compensate such work have not yet opened up. South Korea also wastes electricity. In spring and autumn, power generation often exceeds demand, repeatedly forcing solar farms to curtail their output or shut down entirely. While the U.S. stores surplus electricity to save money, South Korea struggles to store and utilize surplus power effectively. Why is that?
[Lee Si-young / Professor of Electrical and Electronic Engineering, Hongik University: "In South Korea, high-density residential living such as apartments is very common, whereas single-family homes are widespread in the U.S., making North America more accommodating for installing and operating such batteries. Domestically, although residential electricity rates vary slightly, differences by time of use are not very large, which I believe also makes a significant difference."]
The core issue is the rate structure. Household electricity rates in Korea remain nearly flat throughout the day. There is no distinction between cheap and expensive hours to buy low and discharge high, meaning there is little incentive to store power. For resources to be deployed, market returns must match the effort, but such a market does not yet exist. The government, however, has begun taking action.
[Lee Si-young / Professor of Electrical and Electronic Engineering, Hongik University: "There must also be compensation for the capability to flexibly adjust output, but trading mechanisms and market systems for flexible resources remain very underdeveloped in Korea. Although power exchanges utilize these assets, proper market services and compensation structures are lacking. Consequently, ESS operators considering voluntary facility investments in Korea inevitably conclude that 'I will not receive adequate market compensation.'"]
The authorities have begun introducing batteries by guaranteeing profits through long-term contracts and have initiated pilot electricity trading programs in Jeju. Looking back at that Texas settlement screen: "You're getting paid for your solar!" We are already manufacturing the batteries. All that remains is establishing the market that will allow that same sentence to appear on our electricity bills.
(Reported by Jang Seon-i | Story by Shin Hee-sook | Filmed by Bae Moon-san | Video Editing by Kim Hye-ju | Design by Lee Jeong-ju | Produced by SBS Digital News)
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