Battery Storage Payback Calculator
Estimate whether a home battery is worth it, whether you’re pairing it with solar panels or using it to shift usage to a cheap overnight tariff. See annual savings, payback period and a year-by-year projection that accounts for battery degradation.
Cumulative Savings Over Time
Installation Cost Breakdown
Annual Energy Cost Comparison
Year-by-Year Projection
How this calculator works: In Solar + Battery mode, the calculator estimates how much of your currently-exported solar surplus the battery could instead store and discharge for your own use, based on an estimated 300 effective full-cycle-equivalent days a year for solar charging (fewer in winter, more in summer) — this is a planning estimate, not a guarantee. In Standalone mode, it assumes the battery charges fully from the off-peak window each day and discharges to cover usage that would otherwise be billed at the standard rate, capped at your total annual usage.
Battery capacity is reduced year-on-year by your chosen degradation rate, which lowers estimated savings over the projection period. If your chosen cycle life is reached before the end of the projection period, a note will show under your results — batteries typically keep working with reduced capacity beyond this point rather than failing outright, but you may want to budget for reduced performance or eventual replacement.
Always get at least three quotes from MCS-certified installers, and check whether your chosen tariff and export scheme are actually compatible with battery storage before committing.
Home Battery Storage Payback Calculator UK 2026
Our Battery Storage Payback Calculator helps you work out whether a home battery makes financial sense, whether you’re pairing it with existing or planned solar panels, or using it purely to shift electricity use onto a cheap overnight tariff. Choose the mode that matches your situation and enter your own figures for a personalised estimate of annual savings, payback period, and how degradation affects returns over time.
How Much Does Home Battery Storage Cost in the UK?
Battery costs vary by capacity, brand and installation complexity. As a guide, typical fully-installed UK domestic prices in 2026 are as follows.
| Battery Size | Typical Installed Cost | Suitable For |
|---|---|---|
| 5 – 7 kWh | GBP4,000 – GBP6,000 | Smaller homes, partial evening use |
| 8 – 10 kWh | GBP6,000 – GBP8,000 | Average households |
| 10 – 13 kWh | GBP8,000 – GBP10,000+ | Larger homes, higher electricity demand |
All battery storage sold and installed in Great Britain, whether standalone, retrofitted, or with solar, currently qualifies for 0% VAT. Your installer’s quote should already reflect this rather than being something you claim back separately.
How to Use This Calculator
- Choose your mode – Solar + Battery if you have or are adding solar panels, or Standalone if you’re relying purely on a time-of-use tariff.
- Enter your solar or usage figures – annual generation and current self-consumption for solar mode, or annual usage and tariff rates for standalone mode.
- Enter your battery specification – nameplate capacity, usable depth of discharge, and round-trip efficiency from the manufacturer’s datasheet.
- Enter the installed cost – get at least three quotes from MCS-certified installers for an accurate figure.
- Set your degradation and inflation assumptions – defaults are reasonable planning estimates, but you can adjust them.
- Click Calculate Payback to see your results.
Solar + Battery vs Standalone: Which Is Right for You?
These are genuinely different use cases with different economics, which is why this calculator covers both.
| Feature | Solar + Battery | Standalone (Time-of-Use) |
|---|---|---|
| Requires solar panels | Yes | No |
| Requires a time-of-use tariff | No (helps if you have one) | Yes |
| What it saves you | Lost export income vs avoided grid import | Standard rate vs off-peak charging cost |
| Typical payback speed | Slower – limited by excess solar available | Often faster – full daily cycle most of the year |
What Affects Your Battery Payback Period?
- How much excess solar you currently export: if you’re already self-consuming most of your generation, there’s less surplus for a battery to capture.
- The gap between your import and off-peak or export rates: a bigger gap means more value per kWh shifted.
- Battery size vs your usage pattern: an oversized battery for your daily surplus or usage won’t fully cycle, wasting potential capacity.
- Round-trip efficiency: typically 85-95% for modern lithium batteries; every kWh you put in returns slightly less than that out.
- Degradation: usable capacity typically falls by 1-3% a year, gradually reducing how much the battery can shift.
Typical Payback Scenarios (2026)
| Scenario | Installed Cost | Year 1 Saving | Estimated Payback |
|---|---|---|---|
| 10kWh, solar, modest excess | GBP6,500 | GBP150 – GBP250 | 25+ years |
| 10kWh, solar, high excess (large system, low self-use) | GBP6,500 | GBP350 – GBP600 | 11 – 18 years |
| 10kWh, standalone, Intelligent-Octopus-style tariff | GBP6,500 | GBP450 – GBP600 | 11 – 15 years |
| 13kWh, standalone, high usage household | GBP9,000 | GBP600 – GBP800 | 11 – 15 years |
Figures are illustrative estimates only. Enter your own solar generation, usage and tariff figures above for a result specific to your home.
Frequently Asked Questions
Is a home battery worth it in the UK?
It depends heavily on your circumstances. Batteries tend to pay back fastest when paired with a genuinely cheap overnight tariff and high daily usage, or with a solar system that generates a large surplus beyond your own self-consumption. Modest solar surpluses on their own often mean long payback periods. Use the calculator above with your own figures to get a realistic estimate rather than relying on generic claims.
How long do home batteries last, and how much do they degrade?
Most modern lithium home batteries are warrantied for 10 years or 4,000-8,000 cycles, whichever comes first, and typically lose around 1-3% of usable capacity per year. Many continue operating well beyond their warranty period, just with reduced capacity, rather than failing outright.
Do I need solar panels to benefit from a battery?
No. A standalone battery can still save money by charging overnight on a cheap time-of-use tariff (such as an Intelligent-Octopus-Go-style rate) and discharging during more expensive daytime hours. This is a genuinely different use case from pairing a battery with solar, which is why this calculator lets you model either scenario separately.
Is there VAT on home battery storage?
No. Since 1 February 2024, standalone battery installations, batteries retrofitted to existing solar arrays, and batteries fitted alongside new solar panels are all exempt from the standard 20% VAT rate in Great Britain, a relief which has been confirmed as continuing into 2027. This is applied automatically by your installer at the point of sale rather than claimed back afterwards.
What size battery do I need?
For solar pairing, size the battery to roughly match your typical daily excess generation rather than your total daily usage, since oversizing beyond your usable daily surplus wastes capacity that will rarely fully cycle. For standalone time-of-use arbitrage, size it closer to your typical daily usage outside the cheap window, since the battery can only store as much energy as it charges overnight.
Can I add a battery to existing solar panels?
Yes, this is a common retrofit and is straightforward for most systems, particularly those with a hybrid or AC-coupled inverter setup. It also qualifies for the same 0% VAT relief as a battery installed at the same time as solar panels. An MCS-certified installer can confirm compatibility with your existing inverter.
How much can I save with a time-of-use tariff and battery?
This depends on the gap between your standard and off-peak rates, and how much of your daily usage you can realistically shift into the battery’s capacity. Tariffs offering a deep discount overnight (for example, around 7p/kWh against a standard rate in the mid-20s) tend to produce the fastest paybacks of any standalone battery use case, often faster than solar-only pairing with a modest surplus.
Will a battery work during a power cut?
Only if it’s specifically installed with backup or emergency power functionality, which usually requires an additional changeover switch and is not standard on every battery system. Many grid-tied battery systems without this feature will not power your home during a cut, since they’re designed to work alongside the grid rather than replace it. Confirm backup capability with your installer if this matters to you.