I'm not sure that sampling would work in this case. There's a real risk, IMO, of ending up with sampling bias. For example, some communities are very anti-sola

I'm not sure that sampling would work in this case. There's a real risk, IMO, of ending up with sampling bias. For example, some communities are very anti-solar and the local "homeowners" association blocks them. Others are favorable and approve them everywhere having relatively high density. Maybe there's a way to account for this, but I'm afraid that the clustering of installs might cause issues. EDIT: And, to go to your final point, yes, I suspect one goal is to be able to provide really accurate data at a zip code level. I can imagine lots of useful reasons for that, some related to what I said above, too.