Can I add a battery if I have a Feed-In-Tariff?
As we set out in our recent article Is 2024 the year of the battery, Home batteries are going to be a huge trend in 2024 – not just as part of the increasing demand for new solar installations, but as a standalone set-up.
So understandably, many people with existing solar installations are asking “Can I add a battery”? If this is you, and your system was installed fairly recently, the answer is, yes, absolutely, crack on!
However, if you have an older solar system and are paid for the power you generate through a Feed-In-Tariff (typically anything installed pre-2019), it is a bit more complicated. Your feed-in-tariff is a very valuable income stream, so you really do not want to do anything to jeopardise this.
How Feed-In-Tariff (FIT) systems work
Your FIT payments are split into two parts:
- Payment for solar energy generated – up to £0.68/kWh, depending on when your system was installed. This is measured by a meter between the inverter and your home consumer unit.
- Payment for solar energy exported – an additional £0.07/kWh. This is typically estimated rather than measured, as these systems mostly pre-date smart meters. It is usually estimated at 50% of the electricity generated. (To learn more about exporting, you can read our article about the Smart Export Guarantee here)
What you can’t change
You cannot change anything on the solar side of your FIT meter without invalidating your FIT, as this will change the amount of energy being generated.
This means that you cannot add additional solar panels to your system, and you cannot add a battery into that circuit, using the same inverter.
What you can change
You CAN add a battery if you have a separate inverter and it is connected directly to your home’s electricity circuit. This requires a new AC inverter (to convert the AC power in the house into the DC power in the battery when charging, and vice-versa when discharging).
If you do this, then your existing solar system continues uninterrupted, and the generation part of your feed-in-tariff continues as normal.
The export part of your feed in tariff will be affected, as you won’t be exporting as much power to the grid now you have a battery. You’ll need to update your energy company, and they’ll probably come and install a smart meter (if you don’t already have one), to make sure that you get paid the correct amount for what you actually export.
What you lose/gain
This means that for every kWh of electricity your battery stores (instead of exporting), you lose about 7p on the your export FIT, but save the retail price of electricity (currently 28p) if you use that power at peak time. So the net result is a saving of 21p/kWh for every kWh stored in your battery and used later.
When doesn’t this work?
A few households with old solar systems still have an old fashioned analogue electricity meter, that goes backwards when exporting electricity to the grid. This effectively means that you get paid the full retail price of electricity for anything you export. If you have one, lucky you!
As there is no difference between your import and export price, this means that you’re effectively using the grid as a battery. So adding a battery won’t save you money.
And if you did add a battery to a system like this, you’d have to get a smart meter (which would mean you’d just be like everyone else).
If you want to explore further, we are always happy to speak to homeowners about how it all works and help get you one step closer to powering your home with wonderful, renewable energy.