‘All round success’ for Texas’ biggest battery storage system so far

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Solar PV panels at the adjacent power plant in Upton County, West Texas. Image: Vistra Energy.

The largest battery storage system online so far in the US state of Texas has been proven an “all round success” by an independent auditor, a year and a half after it went into commercial operation.

The Upton County battery storage project, a 10MW / 42MWh system installed and commissioned by system integrator FlexGen is at the site of the 180MW Upton 2 solar farm owned by Vistra Energy’s developer subsidiary Luminant. Vistra contracted FlexGen – which counts GE and Caterpillar among its backers – to deliver the battery system, Energy-Storage.news reported back in 2018 as the project got underway.

FlexGen contacted Energy-Storage.news with news that an independent performance review has been undertaken on the Upton project in West Texas, connected to the grid and to markets operated by the Electricity Reliability Council of Texas (ERCOT) around a year and a half ago.

While the integrator did not yet reveal which third party has undertaken the audit process, the 18 months of data reviewed apparently validated FlexGen’s assessment of lifecycle costs – the cost of operating the battery and forecasted wear and tear from use – as well as overall performance.

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“As this segment of the renewables industry is still young and growing, tests like this give utilities the confidence to continue investing in a future with state-of-the-art lithium-ion battery storage,” Steve Panagiotou, FlexGen director of commercial operations said.

“Batteries are green, reliable and becoming more and more affordable – utilities are finding they are critical companions to solar and wind systems in order to provide stability and consistent power for their rate payers,” FlexGen CTO Pasi Taimela told Energy-Storage.news yesterday.

The project injects power to the grid to help the network at peak times or when weather or other conditions cause interruptions to service. It charges from excess solar and from wind in the local area during off-peak times. It also charges up during overnight periods when grid power prices drop and then be discharged to help lower costs of delivering electricity the following morning.

All of these applications are controlled using FlexGen’s energy management software, HybridOS, which is proprietary. The company has recently touted the ability of the software to manage energy storage systems performing a wide range of applications on the grid and off it, including a diesel-replacing project in Indiana that helps make the startup and operation of gas plants more efficient.

It will soon be overtaken for its status as the largest battery storage facility in the state by upcoming standalone battery storage projects from developers Able Grid Energy Solutions and Key Capture Energy, both of which have announced 100MW projects in recent weeks as Texas’ market booms alongside the rapid growth of renewable energy. Another developer, newcomer Broad Reach Power, is developing more than 10 sites of 10MW each in the state with a view to moving onto 100MW-sized individual projects in the next couple of years.

“Places like Texas are promising for renewable energy, because there is plenty of solar and wind power [resource. Battery energy storage systems help stabilise the grid in order to unlock even more renewable power,” FlexGen CTO Pasi Taimela said yesterday.

15 September 2026
San Diego, USA
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