US-headquartered clean energy solutions provider Ameresco’s joint venture (JV) with power producer Atura Power, has begun commercial operations at a 250MW/1,000MWh energy storage project in Ontario, Canada.
The Napanee battery energy storage system (BESS) project’s operational status was announced 19 May by Ontario’s minister of Energy and Mines, Stephen Lecce. The project was reportedly on budget and approximately five weeks ahead of schedule.
In 2023, Napanee BESS Inc, the JV, announced it was a winner in the Ontario Independent Electricity System Operator (IESO) Long-Term 1 (LT1) competitive tender.
LT1, at the time, resulted in the largest BESS capacity procurement in the country’s history, awarding over 850MW of BESS capacity contracts across two tranches during May and June of 2023.
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LT2 was launched in July 2025, it targeted 3TWh of energy generation, alongside 600MW of new capacity resources.
Earlier this month, IESO launched its Long Lead-Time request for proposal (LLT RFP), which looks to procure up to 800MW of long-duration energy storage (LDES).
Ameresco holds a 10.1% interest in the development JV and separately contracted to provide engineering, construction, and other unspecified “expertise” for the BESS installation.
Atura Power, a subsidiary of provincially-owned Ontario Power Generation, developed the Napanee project.
According to Lecce’s announcement, Napanee is valued at CA$600 million (US$435 million), and includes 284 battery storage units, transformer stations, transmission connection facilities and ancillary components, storing electricity from Ontario’s nuclear facilities during periods of low demand and returning that stored power to the system when demand increases.
Notably, the project utilised Ontario’s local supply chain by sourcing 72 medium voltage transformers built by manufacturing company Stein Industries in London, Ontario. The transformers were purchased through Nbisiing Power, an Indigenous-owned electrical equipment reseller operating in Nipissing First Nation.
Additionally, the development and construction of the Napanee project supported 120 jobs, including skilled trades, engineering, transportation, and equipment manufacturing roles.
Atura Power is also proposing another project at the site, the Napanee BESS Phase 2, which would be located next to the existing Napanee BESS project, with a capacity of 300MW/2,400MWh.
Napanee BESS Phase 2 is being proposed through the IESO LT2 procurement. An award through the LT2 would be announced 16 June.
According to the IESO, “the first Window of the Energy Stream of the LT2 RFP has now concluded. The IESO has executed contracts with 13 Selected Proponents, totaling 1,115.10MW of Maximum Contract Capacity and an aggregate Expected Annual Imputed Production of 2.37TWh. The capacity stream of the LT2 RFP is still currently active, and Proposals are being evaluated.”
In April, Quebec-based IPP Boralex and Six Nations of the Grand River Development Corporation (SNGRDC) announced the closing of a US$145.12 million financing for a 125MW/500MWh BESS in Oxford County, Ontario. That project was also awarded through the LT1 process.
Earlier this year, in the US, Amersco completed the second and third in a series of long-term debt financings for projects under a previously announced private shelf facility, provided by financial institution CounterpointeSRE and investment firm Barings, and concurrently transferred certain of the projects’ related investment tax credits (ITCs).
The company claimed that the facility with CounterpointeSRE and Barings streamlined its execution of multiple financings, driving consistency and scale across its pipeline of standalone energy storage and solar‑plus‑storage projects.
