Solar Battery vs Exporting: Which Makes More Money?
Want to know what system suits this tariff?
Export tariffs pay very differently depending on your system size and whether you have a battery. See what setup would actually earn you the most at your home.
Size a System for This TariffFree. Uses your postcode and usage — no phone number needed.
Is it better to use a solar battery or export to the grid?
Using solar electricity yourself (self-consumption) is worth 5–6x more than exporting it. Self-consumed solar saves 26.11p/kWh (the grid rate you avoid paying). Exported solar earns only 4–15p/kWh via SEG. A battery captures surplus daytime solar for evening self-use, converting 4.5p exports into 26.11p savings. The question is whether the battery's extra savings (£200–£400/year) justify its cost (£3,000–£6,000).
The Value Gap: Self-Use vs Export
Every kWh of solar electricity has two possible destinations:
Self-consumption (use it yourself): - Value: 26.11p per kWh (you avoid buying from the grid) - This is the grid electricity rate you do NOT pay
Export to grid (SEG): - Value: 4–15p per kWh (depending on your SEG tariff) - Typical fixed SEG: 4.5p/kWh - Best variable SEG (Octopus Flux peak): up to 24p/kWh for 3 hours/day
The gap: Self-use is worth 1.6–6x more than export, depending on your SEG tariff.
Without a battery: - You self-consume approximately 50% of solar generation - You export approximately 50% at the low SEG rate - Many valuable kWh are 'wasted' at 4.5p instead of saving you 26.11p
With a battery: - You self-consume approximately 80% of solar generation - You export only 20% (mainly in summer when generation exceeds even battery + home needs) - Far more kWh are captured at the high self-consumption value
Source: Ofgem price cap, July-September 2026; SEG rate data.
The Financial Case for a Battery
4kW system — Export-only strategy (no battery): - Self-consumed: 2,000 kWh × 26.11p = £522 - Exported: 2,000 kWh × 4.5p = £90 - Total value: £580/year
4kW system — Battery strategy (10kWh battery): - Self-consumed: 3,200 kWh × 26.11p = £836 - Exported: 800 kWh × 4.5p = £36 - Total value: £820/year
Battery adds: £240/year in extra value
Battery cost: £4,500 Battery payback: 18.8 years standalone
With Octopus Flux tariff optimisation: - Export stored energy during peak (16:00–19:00) at 15–24p/kWh - Recharge from grid overnight at 7.5p/kWh - Additional tariff arbitrage: +£100–£250/year - Effective battery payback: 11–15 years
Key insight: A battery's pure solar self-consumption payback is long (~19 years). But combined with smart tariff arbitrage, it drops to 11–15 years — within the battery's 15–20 year lifespan.
Source: Ofgem; Octopus Flux tariff; Energy Saving Trust.
Want to know what system suits this tariff?
Export tariffs pay very differently depending on your system size and whether you have a battery. See what setup would actually earn you the most at your home.
Size a System for This TariffWhen a Battery IS Worth It
- You are on a time-of-use tariff (Octopus Flux/Go) — tariff arbitrage dramatically improves battery ROI
- You use most electricity in the evening — a battery shifts free solar to when you need it
- Electricity prices rise — every 1p/kWh increase adds £32/year to battery savings (on a 4kW system)
- You want backup power during outages — some batteries provide emergency power supply
- You value energy independence — even if the pure financial ROI is marginal, energy autonomy has psychological value
- Battery prices fall further — if replacement costs drop 30–50% by year 13, the lifetime ROI improves significantly
- You have a large solar system (5kW+) — more surplus to capture = better battery utilisation
When Exporting Is Better (Skip the Battery)
- You are on a high fixed SEG rate (12–15p/kWh) — the value gap between export and self-use is smaller
- You are home during the day (retired, remote worker) — you already self-consume 60–70% without a battery
- Your budget is tight — the £3,000–£6,000 battery cost could go toward more panels instead
- You have a small system (2–3kW) — less surplus means less for the battery to capture
- You plan to add an EV — a smart EV charger (Zappi) diverts surplus to your car at full 26.11p value, acting as a 'battery on wheels'
The Smart Compromise: Battery + Smart Tariff
The best battery strategy combines solar self-consumption with tariff arbitrage:
Daily cycle on Octopus Flux:
06:00–15:00: Solar charges battery + powers home. Export surplus at standard rate. 16:00–19:00: Battery exports to grid at PEAK Flux rate (15–24p/kWh). You earn the highest possible export value. 19:00–02:00: Home uses grid at standard rate. 02:00–05:00: Battery charges from grid at CHEAP Flux rate (7–10p/kWh). Full recharge at minimal cost. 05:00–06:00: Battery powers home until solar kicks in.
Result: You earn 15–24p/kWh for peak exports AND pay only 7–10p/kWh for overnight charging. The 8–14p/kWh arbitrage margin per kWh, across 10kWh per day, earns £300–£500/year in pure tariff profit — on top of solar self-consumption savings.
This is the strategy that makes batteries financially compelling today.
Source: Octopus Flux published rates; battery cycling calculations.
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Want to know what system suits this tariff?
Export tariffs pay very differently depending on your system size and whether you have a battery. See what setup would actually earn you the most at your home.
Size a System for This TariffFree. Uses your postcode and usage — no phone number needed.