UK Power Reserve has chosen Fluence to provide the second 60MW tranche of battery storage it requires to meet Capacity Market commitments.
The reserve power specialist had already contracted Fluence, a Siemens-AES joint venture, to deliver 60MW of batteries to fulfil the 15-year Capacity Market agreements it secured in 2016.
By contracting the firm for the full 120MW/120MWh following two competitive tenders, Fluence said it represents the largest contracted energy storage portfolio transaction to date globally.
The projects must be commissioned before winter 2020, but UK Power Reserve said they would be delivered by end of summer 2019. The first 60MW will be online by March 2019.
The company, now owned by Sembcorp, would not comment on how it will make money from the batteries in the interim, but it is likely to be a blend of contracted services, such as frequency response, as well as arbitraging price differentials in wholesale and balancing markets.