Thanks for this answer. I have a follow-up about AHJ's in Massachusetts. It seems to be the most regulated of all the states. How do you check which AHJ is the right one and make sure of compliance in Massachusetts?
The only real way to find out what the AHJ wants is to contact them.
1-Go down there
2-Give them a call
3-Check their website
Large solar installers have an advantage, because they keep a database and know which AHJs want what. And then there are rumors and discussions with other solar installers. For example, most solar installers I know will not install in Palo Alto CA, because they have a reputation for being "thorough".
If you are trying to find out where to go and what the process it, I would use the same steps. First call the local and then go from there. Usually the building department will know.
For instance when I put PV on my mom's house, I had to get her neighbors to sign something and turn that into the HOA. Then I had to get the City Planning Department to sign off on the plans and after that I got the building permit from the county.
For a job my company is doing this coming week, tomorrow we just go to the City Building Department and they will approve it over the counter (that is the best). The HOA does not require anything in this case.
Also, you have to get a "business license" for each place you install solar. That might be $50 or $100 and you have to register with the city or county.
Bottom line: It is confusing and by making phone calls and being friendly, you will usually find someone who knows the process in the least amount of time.