Someone just asked me if they can repower an 11kW Gaia with a 225kW Vestas.
The answer is yes… but you probably wouldn’t want to!
It’s not possible to de-rate a 225kW down to 11kW… the turbine wouldn’t be able to ‘back off’ enough at medium or higher wind speeds.
That said, you could still install a 225Kw, and run it at full capacity, but then based on my understanding of OFGEMs rules, it sounds like you’d only get pro-rated FiT payments on 4.9% of your generation… which probably isn’t viable.
E.g. If you installed a 225kW and it generated say 450,000kWh p.a. — 4.9% of that would be 22,050 kWh, which at (for example) 34p/kWh would be an annual payment of £7,497.
As buying and installing a 225kW would cost hundreds of thousands of pounds (depends on your site) — but it’s almost certainly not viable.
It is probably possible to repower with a 80kW turbine that could be de-rated to 11kW. If it generated (for example) double the kWh but running at 11kW then OFGEM would pay you on 100% of that, so you’d double your FiT earnings, in theory.
These are only guesstimates, because we don’t sell anything smaller than a 225kW and therefore don’t have actual data to refer to, nor have we helped anyone repower turbines smaller than 80kW.
(We have successfully helped 80kW turbine owners repower with 225kW turbines, and also helped people repower 225kW turbines with 660kW turbines—so we are very familiar with what’s possible there.)
Do get in touch if you have an 80kW (or larger) turbine and would like help repowering.