Anything wrong with tenants installing solar panels?

[Lam N.]

I got an interesting call from one of my best tenants. These are long term tenants. They have never been late in paying rent. They are responsible for all utilities.  It's a 5 bedroom house. 

Anyway, they asked if it is ok for them to have solar panels installed?  They will pay for material and installation.  

Off the top of my head, I said I don't see any reason why not.  Been thinking about it all day.  Still can't think of any reason to say no.

Anyone here can think of a reason for me to say no?