Sounds like a right rip off that offer!! Can you extend your mortgage to cover the cost, cheap loan that way? Panels on your roof have proven to increase property value by £10k.
As househusband stated above, a full 4kw install is way less than half of what you’d be ultimately paying.
Yes solar power is a bit ‘too good to be true’ when you look into it, but it is genuine. I’ve had mine for nearly 2 years now, cost 10K to install, but I have made 2.5k back already in FIT payments plus my Elec bill has reduced by 40%. You get FIT for 25 years, and my forcast is a total ‘income’ of £35k + reduced elec bills.
I keep telling people if they have the money sat in the bank LOSING value every day, then it’s a no brainer to get panels on the roof. If you have to finance them, then obviously you need to find the cheapest loan, which is possibly extending your mortgage.