@Socrates Jean-Baptiste-- Thanks for your patience here. Glad to hear you signed up.
BP actually removed this thread because they misunderstood its intent, but with great assistance and support from @Umar Javaid, they restored it upon further investigation. THANK YOU, UMAR & BP for the research and for discerning the real issues here!
Now... I got the answer to your question yesterday from the Installer-- they handle slate like I described-- it's generally a community solar project. The slate is too risky when it comes to damage, and/or it's too expensive for most people to do it and keep their slate. (Furthermore, JUST my opinion, when you have slate, you probably want to see your slate, not panels over your slate.)
HOWEVER, these are still options on-site at the property: Lower porch roofs are often asphalt or rubber and are targets; Ground mounted-PV is always an option; SOLAR CARPORTS are a very valid idea, too. Each of these, of course, assumes that (1) it's desirable to you in any of those locations and (2) the area (that roof, that drive, that land) has the requisite Southern exposure. If you can't off-set ALL of your power consumption on-site, you can still offset some, and retain that Utility distribution charge savings for what you generate there, then fill in the rest at the Community site... so it's still a valuable exercise to see if some limited PV can be put on the property. Don't forget, the same team will assess your property for heat pumps, simultaneously.
Hope that helps you out. Please help spread the word-- this is open to EVERYONE In Lowell, but only for a limited time. You can refer them to me or any of the Solarize Lowell volunteers.
Thanks!
Steve