Just give yourself and this site a pat on the back. You have saved yourself thousands of pounds and some heartache. Just read some of the stories on here from folks that have been mis-sold to and are trying to get recompense to see what could have happened.
However, please don’t let your initial experience put you off having a further look at solar. You now have a good idea of what return to expect.
So if you can get a quote from a decent ethical installer of around the £6000 mark, then this will bring you in say £850 per year, tax free and index linked. You won’t get anywhere near that from your bank or building society.
best of luck