Timing
The roof needs its dry curing window before anyone walks on it, so the two jobs should not be on the same day. After that the surface is back to normal use and a solar installation can proceed.
If the installation is happening first, tell us: the assessment should see the roof as it will be lived on, including the panels and their mounts.
The penetration question
Solar mounts go through the roof, and every penetration is a place water can enter if the flashing is wrong. Those details are not the treated shingle surface, so a leak at a mount is a repair rather than a warranty claim.
That is not a reason to avoid panels. It is a reason to make sure the installer flashes them properly, and to keep the paperwork for that work.
What to tell the installer
That the shingle surface is treated, so they do not plan to clean or prepare it with anything aggressive while working. And that the roof has a registered warranty, so any repair to a lift or a tear is done with the surface in mind.
Keep the installation date with the roof paperwork, because a later water question starts with "what changed on this roof".
If something goes wrong afterwards
If water appears under a panel after an installation, the first thing to look at is the flashing at the mount. That is a repair, and it is the installer’s work rather than the treatment’s.
If the failure is in the treated surface itself, the remedy starts with a free inspection and the question is asked in that order.
What the panels do to the roof’s job
Panels shade part of the roof and hold debris at their lower edge, so the shingles under them stay damp longer than the rest. That is worth knowing when the roof is being scored, because a damp shaded slope ages differently from an open one.
None of this argues against solar. It argues for doing the two jobs in a sensible order and keeping the paperwork for both.
The questions to ask the installer
Three will do, and any competent installer will answer them without hesitation.
- How are the mounting points flashed?
- Will anything be cut, lifted or walked on that is already fragile?
- Who is responsible if a mount leaks a year later?