The only thing I discussed with provider(from quote 2) regarding hot water was a timer which I figured was pretty standard for most installs? I don’t believe it is any more than that so maybe it was used to make the quote sound better?
Number 1 and 3 quotes were from from same provider - Reviews I checked on them were averaged 4.6/5 from a high volume of sites. Multiple searches showed high level of satisfaction and I couldn’t find any real negative reviews.
They also sold me on the fact they are a Fronius Solutions Partner- apparently a big advantage if there is an Inverter issue as they can fix most issues on site?
N.B. Whilst I originally posted only 3 quotes I had discussions with many others. The reviews weren’t always great with some of them and others simply seemed to cheap to be true.