Battery storage paired with commercial solar serves three functions: (1) time-shifting solar generation from midday to evening peak, (2) providing grid services for revenue, (3) providing resilience against grid outages.
For most commercial sites, function 1 (time-shifting) is the primary driver. A typical 500 kWp solar installation with a 200 kWh battery stores excess midday generation and discharges it during the late-afternoon evening peak when grid prices are highest. This converts low-value export (~5p/kWh) into high-value displacement of imported electricity (~28-32p/kWh).
Battery costs in 2026 are roughly £400-£700 per kWh of installed capacity for commercial-scale lithium iron phosphate (LFP) systems, including inverter, controls, installation. Lifespan is typically 10-15 years with daily cycling.
Payback varies enormously with site profile. A site with strong daytime self-consumption (manufacturing, data centre) sees less battery benefit because the solar is already being consumed when generated. A site with poor self-consumption (warehouse, cold storage) sees much stronger battery benefit because the battery converts otherwise-wasted exports into displaced grid imports.
For sites above ~1 MW, additional revenue stacks become viable: providing dynamic frequency response (FFR/DC) to National Grid earns £20-£60/MW/h, and the Capacity Market provides annual fixed payments of £20-£40/kW/year for committing capacity. These transform the economics for properly-sized batteries on the right sites.
Co-located solar+battery is increasingly the default for new ground-mount projects above 2 MWp, the battery is sized at typically 50-100% of solar capacity (in MWh terms) to enable export-shifting and grid services.