Why commercial solar pairs naturally with battery storage
Solar generation peaks at midday. Most commercial sites have their highest consumption either early morning, late afternoon, or both — when generation is moderate. The mismatch means that without battery storage, a typical commercial solar install exports 30–60% of its generation back to the grid at the Smart Export Guarantee rate (8–15p/kWh in 2026), while later in the day importing electricity at the retail rate (24–32p/kWh). That import-export differential is the single biggest source of value loss in commercial PV — and exactly what battery storage captures.
For UK commercial farms specifically, the case is stronger still. Dairy parlour cooling, robotic milking, poultry shed ventilation, dryer cycles, packing line refrigeration — most farm baseload runs continuously or in distinct evening peaks. A correctly-sized battery stores midday solar surplus and releases it into the evening peak, pushing self-consumption from typically 40–60% (PV-only) to 80–95% (PV + battery).
UK commercial battery sizing — by use case
| Use case | PV size | Battery size | Typical capex | Payback |
|---|---|---|---|---|
| Small farm / workshop | 30–60 kW | 30–60 kWh | £15k–£25k | 6–8 yrs |
| Dairy parlour | 100–200 kW | 100–200 kWh | £35k–£70k | 5–7 yrs |
| Poultry / pig multi-shed | 300–500 kW | 250–500 kWh | £100k–£190k | 5–7 yrs |
| Grain store (seasonal) | 200–500 kW | 100–250 kWh | £30k–£70k | 6–9 yrs |
| Glasshouse / packhouse | 500 kW–2 MW | 500 kWh–1 MWh | £140k–£300k | 5–7 yrs |
| Multi-MW farm campus | 2–5 MW | 1–3 MWh | £280k–£900k | 5–6 yrs |
UK commercial battery brand comparison
Three brands dominate UK commercial battery installs in 2026:
- BYD Battery-Box Premium HV — best value at £350–£420/kWh for systems 50–500 kWh. LFP chemistry, 10-year warranty, strong UK aftermarket. Our most-specified brand for mid-range farm installs. See BYD vs Pylontech detailed comparison.
- Pylontech Force-L2 / Force-H2 — excellent modularity, cells from £380/kWh. Best for staged deployments where capacity grows over time.
- Tesla Megapack / Powerwall Commercial — premium tier at £450–£550/kWh. Best for large-format installs above 1 MWh; Megapack 3 industrial inverter integration is class-leading for utility-scale farms.
See also our full commercial battery storage comparison.
Tax relief on commercial battery storage
UK commercial battery storage qualifies for 100% Annual Investment Allowance against trading profit for incorporated businesses. A £40,000 battery install effectively costs £30,400 after corporation tax relief at 24%. For installs that exceed the AIA cap (£1m as of 2026), the remainder qualifies for super-deduction at 50% in year one. See our 100% AIA deep-dive.
Time-of-use tariff arbitrage — the second income stream
Beyond capturing solar surplus, commercial batteries on flexible tariffs (Octopus Energy Pro, E.ON Next Business Flex, Drax Business) can also arbitrage import-price differentials. A typical UK weekday now sees import prices range from 12–18p/kWh overnight to 28–35p/kWh during the 16:00–19:00 peak — a 17p/kWh spread. A 100 kWh battery cycling once daily through this differential adds £4,500–£6,200 per year on top of solar self-consumption value. We model full tariff-stacked value in every commercial battery quote.
DNO G99 and battery storage
Commercial battery storage requires its own DNO G99 commissioning. For solar + battery installs, we submit a combined G99 covering both assets. Battery export limits are typically more flexible than PV export limits — most UK DNOs accept dynamic-export battery systems that respond to grid signals in real time. See our DNO grid connection guide.
How to get a commercial battery storage quote
Send us your half-hourly meter data, existing solar PV install details (if any), and a brief on your operation. Free desk feasibility within 7 working days — battery sizing recommendation, brand options, tariff modelling, 25-year DCF financial model with three scenarios. If the battery numbers don't stack up against your specific load pattern, we'll tell you upfront.
UK commercial battery storage — common questions
How much does commercial solar battery storage cost in the UK?
In 2026, UK commercial battery storage typically costs £350–£550 per kWh installed for systems below 100 kWh, £280–£420 per kWh for 100–500 kWh systems, and £220–£380 per kWh for systems above 500 kWh. A typical 100 kWh battery alongside a 100 kW solar PV install runs £35,000–£45,000 turnkey including inverter integration. The economics improve significantly when paired with time-of-use tariff arbitrage and demand-charge avoidance on the grid bill.
What size battery do I need with my commercial solar install?
Battery sizing depends on your load profile, generation profile, and the price differential between import and export. Standard rule of thumb: size the battery at 1.5–3 hours of typical evening consumption, with cycle depth around 80%. For a farm with 60 kW evening baseload, that means 90–180 kWh battery. We model this from your half-hourly meter data — the wrong-sized battery is the most common commercial mistake and the difference between a 5-year and 12-year payback.
What battery brand should I specify for a commercial farm install?
The three brands we specify most often for UK commercial farm installs in 2026 are BYD Battery-Box Premium HV, Pylontech Force-L2/Force-H2, and Tesla Megapack/Powerwall. BYD is the best value in the £350–£420/kWh range with strong UK aftermarket. Pylontech offers excellent modularity. Tesla Megapack is the best choice for utility-scale farm installs above 1 MWh. See our detailed BYD vs Pylontech comparison for the brand decision logic.
Does commercial battery storage qualify for tax relief?
Yes — UK commercial battery storage qualifies for 100% Annual Investment Allowance against trading profit for incorporated businesses. This means a £40,000 battery install effectively costs £30,400 after corporation tax relief at 24% (typical for small UK trading companies). For larger installs that exceed the AIA cap (£1m as of 2026), the remainder qualifies for super-deduction tax relief at 50% in year one.
Can battery storage be added retrofit to existing commercial solar?
Yes — AC-coupled battery retrofit is the standard solution for existing commercial solar installs. We connect the battery to the AC busbar via a dedicated battery inverter, bypassing the solar inverter entirely. Retrofit adds 1–2 days to the install programme and typically costs the same per kWh as a new-build battery. DC-coupled retrofit is possible but only economic when the original solar inverter is hybrid-ready. See our DC vs AC coupled comparison.
How does time-of-use tariff arbitrage work for commercial battery storage?
On a flexible commercial tariff (e.g., Octopus Energy Pro, E.ON Next Business Flex), the import price varies through the day — typically 28–35p/kWh during the 16:00–19:00 evening peak vs 12–18p/kWh overnight. A battery charges from solar during the day plus from grid overnight, then discharges into peak-priced periods. For commercial farms with significant evening baseload (dairy parlour cooling, poultry shed ventilation, packing line operations), tariff arbitrage typically adds £4,000–£15,000 per year of value depending on system size.