FlexGen supplied large-scale grid batteries to ERCOT before the energy storage market took off there. Now, the founder has exited and the company has brought on new leaders from the solar startup world to grow business nationwide.

Kelcy Pegler took over as CEO, FlexGen announced Wednesday. Pelger previously served as executive chairman at solar software company Sofdesk, which sold to Enphase Energy earlier this year, and before that he ran NRG Home Solar after the independent power producer acquired Roof Diagnostics Solar, which he co-founded. 

“The FlexGen opportunity just became so apparent that it was the right place with the biggest opportunity to make a difference,” Pegler told Greentech Media. “The market in many ways is catching up to what FlexGen was doing.”

Pegler is joined by new CFO Yann Brandt, who worked at utility-scale solar developer Conergy and guided racking company Quick Mount PV to an acquisition in 2019. Brandt also publishes the daily Solar Wakeup newsletter for industry insiders.

FlexGen assembles batteries, power electronics and controls into utility-scale battery plants, a rapidly growing market. It then operates them with proprietary software controls to manage fleets of projects and bid into ERCOT’s ancillary services markets.

From battlefields to Texas

Founder and original CEO Josh Prueher served in the Navy in Iraq and Afghanistan. He launched FlexGen in 2009 with a focus on reliable, off-grid power for the military. The company later turned to the remote oilfield market, using battery-powered microgrids to reduce fuel costs and improve reliability at those facilities.

That battle-tested track record sets the company apart, Pegler said.

“We didn’t just wake up and say, ‘Let’s make this software capability because we think it could create a lot of value,” he added. “Our software platform has been built over a decade with all the learnings and scars and bruising that occurs in being on the front edge of innovation.”

FlexGen built its first grid-tied battery in Puerto Rico in 2016, then made a splash in the grid-scale storage market by retrofitting a 10-megawatt/42-megawatt-hour battery onto Vistra Energy’s Upton 2 solar plant in West Texas. Not only was that the largest battery in the state by energy capacity, but it also proved out a novel business case by capturing solar production that would have otherwise been unable to be brought to market due to interconnection limitations. 

Vistra later became a leading battery developer in California by converting legacy power plants to newfangled energy storage facilities. FlexGen continued to grow its base in Texas as storage developers showed more interest in the state. The company claims an 80 percent market share of the batteries operating in ERCOT today, in megawatt terms.

Those systems were put to the test during February’s winter storm and grid crisis. 

“In the scheme of winners and losers, our partners and customers were on the winning side of the Texas kerfuffle,” Pegler said, though he declined to share specific numbers.

Change in leadership

Oil and gas investor EnCap Investments launched Broad Reach Power in 2019 to develop battery plants. At the time, Prueher became CFO and FlexGen CTO Doug Moorehead became CTO for the new venture. That put them in the unusual position of leading both a storage integrator and a major potential customer.

Last year, Broad Reach began building two 100-megawatt batteries in ERCOT territory, as well as a portfolio of 15 different 10-megawatt systems. The company declined to name its supplier at the time, though the FlexGen logo was visible in a photo of one of the projects.

Prueher and Moorehead stepped down from their FlexGen posts at the end of 2020. A company press release described the move as “part of a planned, year-long transition to commit 100 percent of their time to Broad Reach Power.”

Pegler said Prueher has been helpful throughout the transition.

“People move on and take on different opportunities,” he noted. “Broad Reach is knocking the ball out of the park.”

Texas was the “tip of the spear” for FlexGen’s entry into the large-scale storage market, but now the company is looking at other states and markets, Pegler said. The business is profitable and “really well-positioned financially” but could raise funds to accelerate its roadmap.