No. Most existing roofs are not engineered for the added wind-uplift forces that solar panels impose. Also, solar panels have become a gimmicky trend now, and proper installation is rarely done. The last thing you want is some random Solar salesman having a crew install solar panels on someones roof without properly flashing every penetration they have to make thru the roof for supports. Unless they provide engineered drawings proving that the current framing of the roof can support the dead load and wind uplift forces imposed by the solar panels, I would definitely reject this. I would also require them to submit flashing details of how they plan to waterproof the roof after they cut/attach thru it.