Your system should have 30-40 years of life. Is it really worth ''going for a cheap quote'' from a company with limited trading history and credentials which suggest that they may not be there to support you in the future if an issue does arise.
With so many adverts focused on ''cheap'' prices it would suggest people still do not get the reality that we generally ''get what you pay for''
A concrete tile bracket has been used, instead of a slate bracket. The bracket has been fixed on top of the slate, rather than underneath the slate and fixed directly to the rafters. The slate has cracked due to the incorrect fixing and has not been replaced, compromising the waterproof integrity of the roof. The lead covering the bracket has not been flashed in. To resolve this issue, the whole system had to be removed, damage repaired and then re-installed - Not by the original install company who refused to respond.
Now that's a good deal !!