Why battery storage economics go far beyond simple peak shaving: grid services, demand charge reduction, and tariff optimisation.
The peak shaving narrative is incomplete
Most discussions about battery storage for commercial sites focus on peak shaving: charging batteries when electricity is cheap and discharging when it is expensive. This is a valid use case and often the simplest to model, but it represents only one of several revenue and savings streams that batteries can deliver. Focusing exclusively on peak shaving understates the true economic value of battery storage, particularly when integrated into a blended renewable energy system.
Demand charge reduction
Many commercial electricity tariffs include a demand charge based on the peak kilowatt demand recorded in each billing period. A single half-hour of high demand can set the charge for the entire month. Battery storage can cap these peaks by discharging during periods of high demand, reducing the recorded peak and therefore the demand charge. For sites with spiky load profiles, such as those with large motors, compressors or batch processes, demand charge reduction alone can justify the battery investment.
Grid services revenue
NESO (National Energy System Operator) pays for capacity that can respond to grid frequency deviations within seconds. Battery systems are ideally suited to this requirement: they can respond almost instantaneously. Participating in frequency response, capacity market, and other grid balancing services generates additional revenue that improves the overall economics of the battery installation. These revenue streams are stacked on top of the site-level savings, creating multiple value sources from a single asset.
Tariff optimisation
Time-of-use tariffs and distribution use of system charges create price differentials throughout the day. Battery storage exploits these differentials by shifting consumption from high-cost to low-cost periods. The savings depend on tariff structure and usage profile, but for sites on half-hourly settled tariffs, the differentials can be substantial. Intelligent battery management systems optimise charging and discharging schedules daily, adapting to real-time price signals and forecast generation from solar or wind.
Battery within a blended PPA
When battery storage is included in a blended PPA alongside solar and CHP, the economics become particularly compelling. Excess solar generation that would otherwise be exported at low value is stored and consumed during peak periods. CHP can charge batteries during overnight periods when electricity demand is low but the engine is running for heat. The result is a system where very little generated energy is wasted, and consumption is optimised around the highest-value times. This is why battery is often the technology that transforms the economics of the overall system.
