One supplier is a reputable electric company. I'm sure they know a lot about electricity but less about Tesla's. The other is founded by guys who used to import Tesla's so have done this 20-30 time already. I am going with the latter, as I think they are more knowledgeable and I needed them to do a good job with convincing the housing committee, which they did. They are installing tomorrow actually at my house. Let me know if you want a referral.