Battery storage has become the most important decision in a residential solar installation. The right battery can double your self-consumption, unlock smart tariff savings worth £500-£1,000/year, and provide whole-home backup during power cuts. The wrong choice — or no battery at all — leaves significant money on the table. Here is YEERS' complete 2026 guide to the four leading systems we install across Yorkshire.
The Four Systems YEERS Installs
Sigenergy SigenStor (5-20kWh modular, £4,500-£12,000 installed) — the most flexible system on the market. Fully modular in 5kWh increments, whole-home backup capability, direct Octopus Flux API integration, and a 10-year warranty. Best for households that want future-proofing and maximum resilience. Approximately £900/kWh installed.
Solax Triple Power (6.3-11.6kWh, £3,800-£7,500 installed) — the value choice. A mature, proven system with a strong track record across thousands of UK installations. EPS (partial) backup, good Octopus Agile compatibility via Solax Cloud API, 10-year warranty. Approximately £750/kWh installed. Best for budget-conscious installations where whole-home backup is not a priority.
Fox ESS ECS (5.1-12kWh, £4,000-£8,500 installed) — strong European credentials and an increasingly popular choice for homeowners who prefer a European-manufactured system. Fox ESS has manufacturing in Poland and strong UK distribution. The ECS series has excellent monitoring software, good round-trip efficiency (93-95%), and a 10-year warranty. Approximately £800/kWh installed.
Sunsynk Hibrid (5-20kWh, £4,200-£11,000 installed) — high capacity in a single unit, making it well-suited to larger homes with high energy consumption. The Sunsynk platform has a strong following among self-builders and off-grid enthusiasts. Good three-phase support. 10-year warranty. Approximately £840/kWh installed.
What to Look For When Choosing a Battery
- Usable vs nominal capacity: Always compare usable capacity, not nameplate. A 10kWh nominal battery may only offer 9kWh usable. All four systems above quote usable capacity in their specifications.
- Cycle life: Look for a minimum of 6,000 cycles at 80% depth of discharge. All four systems above meet or exceed this.
- C-rate: The discharge rate. A 1C battery can discharge its full capacity in one hour. For households with high peak loads (EV charging, induction hobs), a higher C-rate is important. Sigenergy and Sunsynk both support high C-rate discharge for whole-home backup.
- Backup capability: Whole-home vs partial (EPS). As discussed, Sigenergy and Sunsynk offer true whole-home backup; Solax and Fox ESS offer partial backup circuits.
- Smart tariff integration: Does the battery's API connect directly to Octopus Flux, Octopus Agile, or Intelligent Octopus? All four systems support some form of integration, but ease of setup varies.
Real Performance Data from Yorkshire Installations
Across monitored YEERS installations in Hull, York, Harrogate, and Selby, average annual battery performance in 2025 was as follows. Sigenergy 10kWh systems on Octopus Agile achieved average annual savings of £820. Solax 9.5kWh systems achieved £690. Fox ESS 10kWh systems achieved £740. Sunsynk 10kWh systems achieved £760. All figures assume a typical 4-bedroom home with annual consumption of 4,500kWh and a 4kWp solar array.
SEG and Octopus Flux Integration
The Smart Export Guarantee (SEG) pays you for electricity you export to the grid. With a battery, you can optimise export timing — charging the battery during cheap overnight periods (as low as 7p/kWh on Octopus Agile) and exporting during the Flux peak export window (up to 35p/kWh). Over a full year, this arbitrage strategy is worth £200-£400 in additional income on top of standard self-consumption savings.
Payback Periods
Standalone battery retrofit (adding a battery to an existing solar installation): typical cost £3,500-£5,000 installed. Payback period 8-12 years depending on tariff strategy and self-consumption profile. On Octopus Flux with active arbitrage, payback can be as short as 6-8 years.
Solar + battery new installation (combined system installed together): typical combined cost £9,000-£16,000. Payback period 6-9 years. The combined installation benefits from shared commissioning costs and a single scaffolding visit, making it significantly more cost-effective than installing the two components separately.
View our battery storage installation service or use our solar and battery calculator.
