How Much Can a Home Battery Save You?
A home battery can save a typical UK household between £400 and £1,200+ per year. Here's exactly how the maths works.
The basic calculation
Home battery savings come from one simple principle: buy electricity when it's cheap, use it when it's expensive.
With a time-of-use tariff like Intelligent Octopus Go, you pay around 7p/kWh overnight and 29p/kWh during the day. That's a 22p difference per kWh you can shift.
10kWh battery, daily cycle
This assumes 100% efficiency. Real-world batteries are around 90% efficient, so actual savings are slightly lower—but still substantial.
Factors that affect your savings
Battery size
Larger batteries = more savings, up to a point. A 10kWh battery saves roughly double what a 5kWh does. But there's no point going bigger than your daily usage.
Your tariff
The bigger the gap between peak and off-peak rates, the more you save. Intelligent Octopus Go (7p vs 29p) is currently one of the best for battery owners.
Usage patterns
If you're home during the day using electricity, you'll benefit more. If you're out all day, your savings potential is lower.
Solar panels
If you have solar, a battery lets you store free daytime generation instead of selling it back at 4p/kWh. This can add another £200-400/year.
Payback period
The key question: how long until the battery pays for itself?
A well-priced 10kWh system costs around £2,000-3,000 installed. At £800/year savings, that's a payback of 2.5-4 years.
After payback, you're saving £800+ every year for the remaining 10+ years of the battery's life. Over a 15-year lifespan, that's £8,000-10,000 in net savings.
Important: These calculations assume current tariff rates. If peak electricity prices rise (likely), your savings increase. If they fall, savings decrease—but so does your overall bill.
What about solar?
Solar panels add complexity to the calculation. You're no longer just doing tariff arbitrage—you're also storing free solar energy.
The good news: you don't need solar to make batteries worthwhile. Tariff arbitrage alone justifies the investment for most UK households.
If you do have solar, a battery helps you use more of your own generation (boosting self-consumption from ~30% to ~80%), which adds to your savings.
Calculate your exact savings
See how much you could save with your tariff and usage.
Use our calculator →