Solar Battery Storage Sizing (5kWh vs 10kWh vs 13.5kWh): Self-Consumption & Winter Arbitrage
Why adding a 5.1kWh or 10.2kWh LiFePO4 battery boosts solar self-consumption from 35% to 85% and slashes winter grid bills via 7p/kWh overnight charging.
Without a solar battery, a typical UK household working or at school during the day only consumes 30% to 38% of its rooftop solar generation directly, exporting the remaining 62%+ during midday hours.
Adding a 5.1 kWh LiFePO4 battery increases solar self-consumption to ~76%, while a 10.2 kWh battery lifts self-consumption to ~85%—offsetting daytime and evening electricity that would otherwise cost 24.5p/kWh under the Ofgem price cap.
Crucially, modern hybrid inverters allow winter tariff arbitrage: between November and February when solar irradiance is lower, your battery automatically charges overnight between 23:30 and 05:30 at 7.0p/kWh (Intelligent Octopus Go / E.ON Next Drive) and powers your home all day, saving an extra £185 to £460 per year.
Calculate Your Exact 0% VAT Solar & Battery Price
Run our interactive MCS sizing tool to model 440W panel counts, LiFePO4 battery storage, and Smart Export Guarantee payouts for your postcode.
Launch UK Solar & Battery Calculator →