Is Battery Storage Worth It?
An honest, no-sales-pitch analysis of when battery storage makes financial sense — and when it does not.
Battery storage is the most common add-on question we get from homeowners considering solar. And our honest answer is: it depends. For some households, a battery is the single best upgrade they can make. For others, the money is better spent on a larger solar array or simply kept in the bank.
We install batteries almost daily and have strong opinions about when they make sense — but we would rather lose a battery sale than recommend one where the economics do not stack up. Here is our transparent analysis.
2026 Battery Storage Costs
| Capacity | Installed Cost | Example Brands | Payback |
|---|---|---|---|
| 5 kWh | £2,500 - £3,500 | Sigenergy, Fox ESS | 7-9 years |
| 10 kWh | £4,500 - £6,000 | Sigenergy, Tesla Powerwall | 6-8 years |
| 13.5 kWh | £6,500 - £8,000 | Tesla Powerwall 2 | 7-9 years |
| 16+ kWh | £7,500 - £10,000 | Sigenergy (stacked), BYD | 8-11 years |
Prices include installation and VAT (0% when installed with solar, 20% for standalone retrofit). Costs vary by brand, configuration, and installation complexity.
Should You Get a Battery? It Depends on Your Situation
You already use most of your solar generation directly. A battery adds less value when self-consumption is already 60-70%.
Classic battery case. You generate during the day but use most electricity in the evening. A battery shifts solar to peak hours.
Charge from grid at 7.5p/kWh overnight, discharge at 29p/kWh during the day. The arbitrage alone often justifies the battery.
If you work from home or have medical equipment, backup power can be invaluable. Not all batteries offer this — we specify accordingly.
A small system generates limited surplus. Battery payback is longer when there is less excess energy to store.
0% VAT on the battery when installed with solar. Integrated design from day one. Lowest total cost and best ROI.
The Maths: How We Calculate Battery Payback
Battery payback depends on three factors: how much solar surplus you have to store, the difference between grid import and export rates, and whether you use a time-of-use tariff.
For a typical Wiltshire home with a 4kW solar system and a 10kWh battery, self-consumption increases from approximately 45% to 85%. On a flat tariff at 29p/kWh import and 10.8p/kWh export, that shift is worth approximately £550-£700 per year in additional savings. On a time-of-use tariff with 7.5p overnight rates, the value can exceed £900 per year.
At a 10kWh battery cost of around £5,000 (installed with solar at 0% VAT), payback falls between 6 and 8 years. The battery warranty is typically 10-12 years, giving you 2-6 years of pure profit before any degradation concerns.
Our Recommendation
If you are installing solar panels and your household pattern involves low daytime / high evening usage, add a battery. The 0% VAT saving alone (worth £800-£1,200 on a typical battery) makes the economics compelling, and it disappears after March 2027.
If you already have solar panels and are considering a retrofit battery, the decision is more nuanced. The standalone battery attracts 20% VAT, increasing cost and extending payback. We will always give you an honest assessment during our free survey.
Key Numbers
Battery & EV
Storage and smart charging to maximise every unit you generate
Battery Storage FAQs
Battery storage is worth it if you use most of your electricity in the evening (when solar panels are not generating) or if you want protection from power cuts. A battery typically increases self-consumption from 30-50% to 80-90%, making more of your solar investment pay for itself.
Modern lithium-ion batteries typically last 10-15 years, with most manufacturers offering 10-year warranties guaranteeing at least 70% capacity retention after 6,000+ charge cycles. Battery technology is improving rapidly.
Yes. Lumos Energy regularly retrofits battery storage to existing solar panel systems. We assess your current setup, recommend a compatible battery, and install it alongside your existing inverter or with a new hybrid inverter if needed.
Many modern battery systems offer backup power functionality, but not all. If power cut protection is important to you, we ensure your system specification includes this capability. Some systems switch to backup within milliseconds.
Related Services & Guides
Battery Storage Near You
We install battery storage throughout Wiltshire, Somerset, Bath, and Gloucestershire.
Get an Honest Battery Assessment
We will tell you whether a battery makes sense for your home — no sales pitch, just honest advice based on your usage.
Free survey · No obligation · Broughton Gifford, Melksham · Open Mon–Fri 8am–6pm, Sat 9am–2pm