Home › Guides › Adding panels
Adding panels to a system already on the tariff
The question is always the same: will the new panels be paid at my old rate? Almost certainly not, and the gap is large enough to change the decision.
Why it matters so much here. A 4kW domestic system accredited in 2010–11 is paid up to 76.90p a unit today. The same system accredited in 2018–19 is paid up to 5.85p. Panels added now fall outside the scheme altogether, because it closed to new applicants in 2019.
What the register shows
10,266 of the 869,807 entries on the register are flagged as extensions. So this is not unusual, and it is well trodden ground for the licensees.
The rule, and the part to check
An extension is generally treated as a separate installation, with its own eligibility date and therefore its own tariff, rather than being absorbed into the original at the original rate. Since the scheme closed to new applicants on 1 April 2019, panels added today are not eligible for a Feed-in Tariff at all.
How that is applied to your particular installation is a question for your FIT licensee, and worth asking in writing before anything is fitted. The detail matters and we are not going to guess at it on your behalf. What is not in doubt is that adding panels will not extend your existing rate to them.
Does it put the original at risk?
Changing an accredited installation is something your licensee needs to know about. The generation tariff on your original system is much the larger payment and runs for the rest of your term, so the sequence matters: ask first, get the answer in writing, then install. Not the other way round.
The alternative worth weighing
If the goal is to get more out of the roof rather than more from the scheme, the money is now in what you stop buying rather than in what you are paid. That points at using more of what you already generate, which is the battery question, and at the Smart Export Guarantee for anything genuinely new.
Extension counts from the Ofgem Feed-in Tariff installation report of 2025-12-31. Rates from the Ofgem tariff table for 2026-27. How the rules apply to a specific installation is a matter for your FIT licensee. Information only, and not financial advice.