Mom walked away from meeting and solar lease. Advice?

Check to be sure they have not filed a lien.

My mother had been showing signs of dementia, but she hadn't been officially diagnosed yet. A huge wake up call was when she signed contracts (without having any understanding of what she was signing) for solar panels, which included financing through the company. I got a call from a neighbor asking me if I was aware of any of this. I wasn't -- it wouldn't have occurred to my mother to contact me or inform me. I got that phone call at work, and tried not to freak out. The solar company told me exactly what it told you, and I told them they would hear from my attorney (I don't have an attorney).
My boss, thanks to her level head, recommended I call our company's EAP and let them know I would need an attorney for this matter. If you have this resource, give them a call. Otherwise, do a quick search for attorney's in your area, and ask them if they'd charge a flat fee for a cease and desist letter. Have it drawn up, and mailed/faxed/emailed to the solar company.
It was hugely stressful, and it cost us about $450, but it did the trick. The solar company just disappeared, thank goodness.
Good luck!