Let’s do the maths. Approximately, and noting that interest rates will have changed, etc. etc.

Assume you buy a 5kWh battery for £5k installed (noting that prices continue to come down rapidly). The battery should save you about £700 per year by buying cheap electricity overnight (at about 9p/kWh instead of 28p/kWh daytime rate), or by storing electricity from solar panels.

The average three-bedroom household will save £700 per year with a solar battery:

Source: The Eco Experts

If you repay the £5k loan over 5 years your monthly repayment will be about £100 and you’ll pay £1,040 in interest over all.

The battery will have saved you £3500 in that time. Your electricity bills will be £58 lower, on average, so the loan for the batteries is costing you £40/ month.

Once the loan is repaid you continue to save £58 per month (more, assuming inflation). Breakeven is at 7 years. By year 10 you will have ‘made’ £2000.

So it’s well worth thinking about.

At the moment batteries are zero rated for VAT, so that’s a 17.5% saving straight away, making it even more useful to buy now, even if you have to take loan. If you can add the loan to your mortgage, the interest rates will be lower still.

Note that this is all based on some assumptions: costs of loans, cost of batteries and cost of electricity. A proper calcualtion for your needs should be done, but it gives you an idea of what to expect.