Maybe this is similar to your solar agreement.  This arrangement needs no investment up front by the homeowner -- just an agreement to purchase the power generated by the solar panels for X number of yrs.    Report describes how the rates for the solar generation are generally set just a bit below the power company's cost levels. So you'd be getting some percentage of discount, whenever its sunny enough?  

When you don't need that power, but its going back --i.e. sold -- into the utility grid, what would be that rate?  Seems those would be credits coming back to lower your costs.  Wondering if there's any movement of your rates over those term of years. 

I'm not sure what happens at the end of the term of years? Or if a panel gets damaged, how would that get fixed.  If your roof needs repairs do they uninstall, & set aside, then reinstall the panels?