Add Battery Storage
Battery storage lets you store solar energy during the day and export it during evening peak hours when SEG rates are highest. With the right tariff, a battery can more than double your export earnings.
Why Add a Battery?
Earnings Comparison: With vs Without Battery
| Scenario | Export Rate | Annual Export | Annual Earnings |
|---|---|---|---|
| Solar only (fixed rate) | 24p/kWh | 1,800 kWh | £432 |
| Solar + Battery (Agile avg) | ~28p/kWh avg | 2,200 kWh | £616 |
| Solar + Battery (peak only) | ~32p/kWh avg | 2,200 kWh | £704 |
Based on a 4kW solar system in Central Scotland. Actual earnings depend on system size, location, and usage patterns.
Battery Sizing Guide
| Solar System | Recommended Battery | Typical Cost | Payback (est.) |
|---|---|---|---|
| 2-3 kW | 3-5 kWh | £2,000-3,000 | 5-7 years |
| 4-5 kW | 5-10 kWh | £3,000-5,000 | 4-6 years |
| 6-10 kW | 10-13 kWh | £4,500-6,500 | 4-5 years |
Costs include installation. VAT-exempt when installed alongside or added to a solar system. Payback estimates include both self-consumption savings and export earnings.
Best Tariffs for Battery Owners
Frequently Asked Questions
How does a battery increase SEG earnings?
A battery lets you store solar electricity generated during the day and export it during evening peak hours (4-7pm) when variable SEG rates like Outgoing Agile can exceed 35p/kWh, instead of exporting during the day when rates may be lower.
What size battery do I need for SEG export?
For a typical 4kW solar system, a 5-10kWh battery is ideal. This stores enough to cover evening household use and export surplus at peak rates. Larger systems (6kW+) benefit from 10-13kWh batteries.
Does adding a battery affect my SEG eligibility?
No. Adding a battery does not affect your SEG eligibility. However, Ofgem requires that you only export electricity generated from eligible renewable sources, not electricity imported from the grid.
How much does battery storage cost?
Battery storage typically costs between £2,500 and £6,000 installed, depending on capacity. A 5kWh battery might cost around £2,500-3,500, while a 10kWh system is typically £4,000-6,000. Batteries are VAT-exempt when installed with solar.
What is the Octopus Outgoing Agile tariff?
Outgoing Agile is a variable SEG tariff from Octopus Energy that pays different rates every 30 minutes based on wholesale prices. Evening peak rates (4-7pm) often exceed 30p/kWh, making it the most profitable tariff for battery owners.
Specialist Battery Installers
Looking for expert advice on adding battery storage to time your solar exports? Our MCS certified team covers Scotland and Northern England.
Get a Battery Quote
We are MCS certified battery installers covering Scotland and Northern England.