PeakGen and Zenobe have won £8.7m in contracts to provide reactive power, which helps keep voltage stable, in Mersey.
National Grid said it had picked the two firms from 15 bidders.
Zenobe, which counts former National Grid CEO Steve Holliday as non-executive chairman, owns and operates a network of battery storage schemes. PeakGen runs diesel farms and battery assets.
However, the ESO said the contract will result in a novel approach: a reactor which absorbs reactive power, and battery which will be able to operate in additional markets alongside its reactive power contract.
The nine-year contracts run from 2022.
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