The IDEAL solution would be coming from a Roofing company that also installs Solar systems on top. This all-in-one service would be safest & possibly least costly, all within a safety net most of us are not qualified to provide.
IMHO, I judge this project outside the DIY scope. Moving, upgrading roofing & solar can be on the scope of work table for others. Because getting solar out of the way of new roofing is so expensive, it may explain sale of the house to avoid such and also bring to mind a new forever roof material ... perhaps metal .... to avoid the solar move expense once again.
Unless the energy bills suggest otherwise, I would be tempted to sell the removed-by-others solar system to free your mom of such maintenance (& chemicals inside them should they leak via hail/other), install an energy-friendly forever metal roof for her and sleep well for years ahead.
Gotta draw since me got no grammar MasterArch '76