IN Brief:
- Cero Generation has signed a seven-year tolling agreement for its 70MW/140MWh Lower Larks battery near Bristol.
- Danske Commodities will manage the asset’s full market exposure and dispatch across wholesale and ancillary-service markets.
- The two-hour system is scheduled to enter commercial operation during the second quarter of 2027.
Cero Generation has appointed Danske Commodities to optimise its 70MW/140MWh Lower Larks battery energy storage system under a seven-year tolling agreement covering the asset’s full market exposure.
Developed near Bristol by Cero Generation and Enso Energy, the two-hour battery is scheduled to enter commercial operation during the second quarter of 2027. Its duration allows it to combine wholesale trading with balancing and ancillary services across a wider operating window than shorter systems.
Danske Commodities will control market participation and dispatch under the tolling structure. Cero will receive contracted revenue in return for making the battery available, while the optimiser assumes responsibility for capturing value from electricity price spreads and eligible system services.
Lower Larks completes the wider Larks Green development, where solar generation and battery storage share a location and elements of the electrical infrastructure. The battery will be able to respond independently to market conditions while also providing a route to manage renewable output and connection capacity more actively.
Its operating strategy will remain constrained by state of charge, charge and discharge rates, round-trip efficiency, auxiliary demand, cell temperature, cycle limits, warranty conditions, and degradation. Dispatch decisions must preserve long-term asset condition while meeting contracted availability requirements.
A seven-year agreement provides greater revenue visibility than full merchant exposure during the early operating life. It also transfers trading complexity to an organisation with continuous access to wholesale, balancing, and ancillary-service markets.
Construction, grid connection, equipment performance, and long-term degradation remain with the project, while the detailed contract will allocate responsibility for outages, efficiency losses, capacity fade, market-rule changes, and underperformance.
Tolling separates ownership from dispatch
Britain’s battery market initially developed around a relatively narrow group of frequency-response services, but operators now combine wholesale arbitrage, the Balancing Mechanism, reserve products, local flexibility, and Capacity Market income.
The number of revenue routes has increased alongside the complexity of switching between them. A battery committed to one service must still retain sufficient state of charge and availability to meet that obligation while responding to changing wholesale prices and system conditions.
A tolling agreement can stabilise cash flow by giving the owner a fixed or structured payment for availability. The optimiser decides when to charge, discharge, or hold capacity, while assuming the associated market exposure.
Batteries differ from conventional generation because every dispatch changes state of charge and contributes to degradation. Optimisation must therefore account for the physical cost of cycling, rather than pursuing revenue without considering its effect on asset life.
Lower Larks’ two-hour duration provides enough energy to move significant volumes across intraday price periods and support longer system events than a one-hour battery. It remains shorter than the four-hour systems entering parts of the UK pipeline, so returns will depend on price shape, service requirements, and efficient allocation of the available 140MWh.
Changes to dynamic-response procurement rules are altering the operating environment for batteries active in rapid frequency services. Evolving market requirements increase the value of optimisation systems capable of adjusting bidding and dispatch as products change.
The optimiser must maintain a live view of electricity prices, service commitments, imbalance exposure, grid instructions, asset condition, and forecast availability. Automated dispatch is therefore linked directly to the plant controller, metering, communications, and battery-management system.
Cybersecurity, data quality, fail-safe operation, and clear control ownership are essential because a software or communications failure can create both physical and financial consequences. The operating boundary between optimiser and asset owner must remain unambiguous during faults or abnormal conditions.
Longer contracts support larger batteries
Battery projects require substantial upfront spending on cells, containers, inverters, transformers, switchgear, protection, fire systems, civil works, controls, and grid connections. Merchant revenue can fluctuate considerably over the financing period, particularly as more capacity enters the same services.
Contracted optimisation income can improve debt coverage and reduce the amount of market risk retained by investors. Several commercial structures are now emerging, including management fees, revenue floors, swaps, shared upside, and full tolling agreements.
The same movement towards longer duration and more structured revenues is evident in the financing of the four-hour Coalburn battery. Duration and contracted income are becoming central to the bankability of larger projects.
Co-location introduces additional operating choices. Lower Larks may charge from the grid, adjacent solar generation, or both, subject to the connection agreement, metering configuration, and applicable market rules.
Sharing a connection can reduce capital cost and improve utilisation, although control systems must prevent combined imports or exports from exceeding agreed limits. Storage may also absorb solar output during local export constraints, but cannot necessarily resolve restrictions that limit later discharge through the upstream network.
By 2027, the British market will contain more battery capacity, revised ancillary-service procurement, and a larger share of renewable generation. Competition is likely to compress returns in mature services while rewarding assets capable of moving efficiently between markets.
The tolling agreement places that responsibility with Danske Commodities from the beginning of operation. Before commercial dispatch can start, construction and testing must validate cell balancing, thermal control, inverter response, protection coordination, communications, and metering.
Across thousands of charge and discharge decisions, optimisation will become part of the plant’s operating system rather than a separate trading service. The contract gives Lower Larks a defined commercial route, while its long-term performance will depend on disciplined control of both market exposure and battery condition.
