Battery Storage
Millions of UK homes have solar panels but no battery storage. With electricity prices high and battery costs lower than they've ever been, 2026 is a compelling time to add storage. But retrofitting isn't always straightforward — the right approach depends on your existing inverter, how your system was wired, and how much storage you actually need.
An AC-coupled battery connects to your home's AC wiring — essentially it's a separate system that stores energy from the grid or solar. This works with any existing inverter, regardless of age or brand. It's the most common retrofit approach because it doesn't require changing your existing inverter.
Downside: there's a small efficiency loss from double conversion (DC→AC→DC→AC). In practice this is around 5–8%, which rarely changes the financial case significantly.
A DC-coupled battery connects directly to the solar panels' DC output via a hybrid inverter. More efficient, but requires either replacing your existing inverter with a compatible hybrid model, or that your existing inverter is already hybrid-ready. If your existing inverter is a compatible hybrid model with an unused battery port, DC-coupling is straightforward. If not, you're also paying for an inverter upgrade.
| Battery | Capacity | Installed Retrofit Cost |
|---|---|---|
| Fox ESS AC battery | 10kWh | From £5,995 |
| SolaX AC battery | 9.5kWh | From £5,995 |
| Tesla Powerwall 3 | 13.5kWh | From £8,495 |
All retrofit prices include installation, commissioning, integration with existing monitoring where possible, and installation certification (0% VAT applies).
AFTA Electrical covers Essex, Suffolk, Norfolk, Cambridgeshire, and Hertfordshire. NAPIT & TrustMark registered.
Yes, in most cases. We assess your existing inverter's compatibility during a free survey. If it's not hybrid-capable, we'll recommend an AC-coupled battery that works with any inverter.
A 10kWh battery retrofit typically costs £5,995–£8,495 installed depending on brand and coupling method. 0% VAT applies as battery storage qualifies for the reduced rate.
DC-coupled is slightly more efficient but requires a compatible hybrid inverter. For most retrofits, AC-coupling is the more practical and cost-effective solution.
No — you still receive SEG payments for electricity you export. A battery may reduce the amount you export (because you're storing it instead) but the SEG rate applies to whatever you do export.
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