Holes Bay battery plant. Image: National Grid

National Grid ESO’s new application programming interface (API) has opened GB’s balancing market mechanism to small generators.

The electricity system operator’s (ESO) API introduces a new simple, web-based route for providers to connect and communicate in real time with its systems and the balancing mechanism. It also provides an alternative to the fixed line connections that providers have traditionally used for electronic data transfer and electronic dispatch logging.

The innovation should open the market to a wider range of providers and technologies and take the ESO a step closer to being able to operate a zero carbon grid by 2025, according to a statement.

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“As we shift away from fossil fuel generation to cleaner, decentralised power, new opportunities are emerging to diversify our energy mix and make our electricity system smarter and more flexible,” says Roisin Quinn, head of national control and chief engineer at National Grid ESO. “Our wider access initiative is helping to drive that change.”

The first user to go live with the new API was Tesla, using its automated real time trading and control platform Autobidder to manage first time balancing mechanism access for Fotowatio Renewable Ventures and Harmony Energy’s 7.5MW/15MWh Holes Bay battery energy storage plant in Dorset.

Market participants can develop their own API solutions to interface with the ESO’s new API, with the ESO providing a secure development and testing environment, and certification on completion.

National Grid ESO says the API rollout marks the latest development in its plans to remove barriers to access for a wide range of providers, and to boost the rea -time flexibility of the system.

Last year the ESO and the balancing and settlement code administrator Elexon lowered the minimum threshold for taking part in the balancing mechanism from 100MW to 1MW, to enable entry for smaller and aggregated units in regional networks.

In April, demand response provider Flexitricity became the first to take advantage of wider access changes to register in the balancing mechanism as a virtual lead party – a new type of market participant exempt from needing a supply licence or paying use of system charges.