Fox ESS: Modular and Flexible
Fox ESS offers a range of modular LFP battery systems from 5kWh upwards. The EVO 9.6kWh (£4,500-£5,500 installed) suits most 3-4 bedroom homes and pairs with the FoxCloud app for smart tariff scheduling and real-time monitoring. All Fox ESS batteries use LiFePO4 chemistry with 6,000+ cycle life and a 10-year warranty. The modular design lets you start smaller and expand capacity as needed — ideal if your energy requirements may grow over time.
Tesla Powerwall 3: All-in-One Power
The Tesla Powerwall 3 provides 13.5kWh in a single unit at £7,000-£11,500 installed. It features 11kW continuous output (versus 5kW from Fox ESS), 97.5% DC efficiency, and a built-in inverter. The Tesla app integrates with the broader Tesla ecosystem (Powerwall, Solar Roof, Tesla vehicles). The main consideration is the fixed 13.5kWh size — you cannot start smaller — and a higher installed cost than equivalent Fox ESS capacity.
Which Should You Choose?
Choose Fox ESS if: you want a modular system, strong value per kWh, smart tariff optimisation, or the ability to expand capacity later. Choose Tesla Powerwall 3 if: you need high continuous output (e.g., for a heat pump), you want a single all-in-one unit, you prioritise backup power, or you prefer the Tesla brand ecosystem. We install both and recommend the right system based on your specific energy usage during the free survey.
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