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Second life for EV batteries

California company B2U Storage Solutions is working to help establish a second life for electric vehicle batteries--sourced from Honda and Nissan--with a new solar+storage facility.

By Robin Brunet

There may be a huge marketing buzz around electric cars, but they have a ways to go to further reduce the impact of vehicles on the environment.

In addition to their potential to create demand for more electricity, the biggest challenge they pose, according to critics, is that their lithium-ion batteries are not widely recycled (unlike traditional lead-acid batteries) and are rapidly reaching the end of their lives as the first generation of electric cars are scrapped.

It’s a worrisome problem: it’s been estimated that over 30 million EVs will be on the roads in Europe alone by 2030 (comparable figures apply to the U.S.), and since only five percent of their power sources are recycled at most, some analysts believe a new kind of environmental crisis could occur in 10 or 15 years.

But what if the batteries could be used for a truly green purpose instead of contributing to landfills?

That’s the question car makers have been exploring for years now, and thanks to a hybrid solar and storage facility called SEPV Sierra in Lancaster, California, a breakthrough has been achieved.

There, on the edge of the Mojave Desert, an array of solar panels sits next to dozens of long white boxes filled with 1,300 used EV battery packs sourced from Honda and Nissan. This low-slung facility may strike observers as bland and uninspiring, but it has been producing 25 MWh of electric storage capacity since January. The brain behind the project is Santa Monica-based B2U Storage Solutions, which develops and operates large-scale energy storage systems using second-life EV batteries. And the beauty of the facility is the company’s patented EV Pack Storage—EPS—technology, which eliminates repurposing costs in addition to achieving effective yields.

SEPV Sierra is interconnected directly to the grid, providing power to California’s wholesale energy market and generated over $1 million in revenue in 2022 alone (the facility began commercial operations in 2020, and its capacity was scaled up in phases).

The SEPV Sierra facility in California represents the largest operational UL 9540-certified Energy Storage System utilizing second-life EV batteries anywhere, and showcases B2U Storage Solutions’ EV Pack Storage technology.

The 25 MWh deployment represents the largest operational UL 9540-certified Energy Storage System utilizing second-life EV batteries anywhere, on any continent, and showcases B2U’s EPS technology.

Even though the project represents a small fraction of the solar storage needed globally (the International Energy Agency calculates that the world will need 44 times more grid-scale storage between now and 2030 if net-zero goals are to be achieved), SEPV Sierra’s efficiency suggests that other projects can follow its lead, with even more upscaling being entirely feasible.

“We found a way to avoid the old process of disassembling the parts of the battery and rewiring, which was expensive and a huge impediment,” says B2U Co-Founder and CEO Freeman Hall.

Hall is no stranger to energy innovation. He founded B2U in 2019 with partner Mike Stern as a spinoff of Solar Electric Solutions, which since 2008 had developed over 100 MW of solar PV across 11 different sites (B2U later raised a $10 million Series A equity round in 2021, led by Japanese conglomerate Marubeni Corporation).

Hall and Stern had acquired the Lancaster site in 2017; it had previously been used by another developer as a solar thermal plant that produced steam to power a generator. “It was nothing more than a research and development project,” Hall says. “We thought it was a perfect opportunity to repurpose the site for battery energy storage charging from on-site solar PV. We could then sell the power into the grid during the evening hours, when power is needed the most.”

The site for the SEPV Sierra hybrid solar and storage facility in Lancaster, California is on
the edge of the Mojave Desert, and features an array of solar panels sitting next to dozens of long white boxes filled with 1,300 used EV battery packs sourced from Honda and Nissan.


But turning a dream into reality required considerable research, in this case close collaboration with contacts at Nissan and Honda. Hall recalls, “Nissan was busy developing the best ways to repurpose the batteries in their line of electric vehicles, and we were struck by a number of things, first and foremost being that the first generation of EVs—in this case the Nissan Leafs—hit the road in 2011 and were reaching the end of their life, meaning a steady stream of batteries was becoming available for reuse.

“Second, studies led us to believe that when an EV battery is removed from a vehicle, they still have 60 to 80 percent of the original capacity. That’s because in a car it takes a lot of power to accelerate, but for stationary storage applications, the batteries charge and discharge slowly each day and are operated at a lower current.”


In addition to deploying Honda and Nissan EV batteries at scale, B2U has also successfully tested GM Bolt and Tesla Model 3 battery packs with its EPS system, demonstrating the all-important ability of the system to be configured to operate any EV battery.


But what really galvanized Hall and Stern was their ability to avoid the costly practice of taking the battery apart and rewiring them. “Our ‘plug and play system’ leaves the batteries in their original casing and uses the original battery-management tech they came with,” Hall says. “This alone is a game changer.”

Indeed, the batteries at SEPV Sierra can simply be wired together, and the manufacturer’s original software can be deployed instead of going to the time, trouble and expense of creating new software.

“Our EPS system’s cabinet controllers connect and disconnect batteries wired in series and parallel strings during charge and discharge cycles, so that weaker batteries with lower capacity would not limit the output of stronger batteries,” Hall explains.

“This approach enables our system to achieve an efficient energy yield despite the variances in capacity inherent in second life batteries. Ultimately, our approach to reuse helps drive down costs and add more value for the whole industry, for car manufacturers and for consumers.”

B2U removed various components at the Lancaster site, which Hall describes as “otherwise favourable for redevelopment.” The company then installed a small-scale system in 2020. “Its function proved that our core hypothesis worked very well, so the following year we expanded operations,” he says. In total, some 400 Jinko 410W solar modules were mounted on ATI trackers. The project also required SMA’s energy storage solution with three Sunny Central inverters, each inverter paired with six DC-DC converters.

 The solar power portion of the SEPV Sierra project features some 400 Jinko 410W solar modules mounted on ATI trackers, and three SMA Sunny Central inverters.

The EPS system provided safe and reliable operation around the clock, continuously monitoring and controlling each battery to ensure their specifications were maintained. “We crossed the 25 MWh threshold this past New Year, announced it in February, and may ultimately expand the site to produce 28 MWh,” Hall says.

In addition to deploying Honda and Nissan EV batteries at scale, B2U has also successfully tested GM Bolt and Tesla Model 3 battery packs with its EPS system, demonstrating the all-important ability of the system to be configured to operate any EV battery.

February’s achievement represents the potential pathway to a solution of two serious issues: in addition to the growing need to recycle or repurpose used batteries, the accelerated growth of clean but intermittent solar power added to the California grid potentially causes lower reliability. This is due to an increasingly volatile net load (demand less renewable supply), which in turn is caused by excess power supply during daylight hours and lower supply during high-demand evening hours.

But now, when California homes need more power and the supply of solar drops, the B2U solar/battery hybrid sends electricity back into the grid. Looking forward, the growth of used EV battery capacity in the U.S. and around the world will be tremendous and may reach more than 200 GWh annually by 2030, according to a 2019 report by consultants, McKinsey Group.

As usual, Europe seems to be ahead of the U.S. in the sector Hall and Stern are helping to develop. Finland’s state-owned energy firm Fortum spearheaded a second-life battery installation in 2021 at a hydro power plant in Sweden, using out of service batteries from Volvo. Norway-based ECO STOR has developed grid and industrial Energy Storage Systems (ESS) running on used batteries, and Finnish startup Cactos operates energy storage facilities with a capacity of 100 kilowatt hours thanks to recycled Tesla batteries.

Even Canada is jumping on the bandwagon. Last year, ESS provider Moment Energy struck a supply agreement for second-life EV batteries from Mercedes-Benz. 

But for B2U at least, used EV batteries are rapidly transforming from a potential environmental problem to an energy-generating opportunity for decades to come. 

“We need a lot of energy storage, and as we speak, millions of convention automobiles are being retired in North America with EVs taking their place, so EV batteries will continue to be in abundance going forward,” Hall says. “Recycling at a huge scale is coming. Will we be able to meet California’s goal to source 90 percent of its electricity from renewables by 2035? I don’t know, but we’re excited to be part of the movement that will contribute to achieving that objective.”

Q2 2023