Whilst a battery does not save carbon in itself, it does mean that the carbon and cost savings from the solar PV are maximised. Renewable energy generation is not constant – it fluctuates depending on the weather. Similarly, there are peaks and troughs in demand for electricity. If we can store excess green electricity and use it later, the UK electricity grid does not need to rely so heavily on electricity generated by fossil fuels to meet peak demand. As well as storing excess electricity that your solar panels generate during the day, you can store electricity at night from the grid, when demand is lower, and the electricity mix is greener.
Adding a battery to a solar PV system has become very common.
Please note, if you install a battery as part of your solar PV system, the whole thing is exempt from VAT. However, as batteries are not classed as energy saving measures in their own right, they are subject to VAT if installed separately i.e. at a later date. Therefore, you may lose out financially if you postpone the decision to get a battery, plus the job may be less attractive to installers.