I have a big commercial grow operation coming up that's going to need an electrical service larger than 1200A, and 1200A is the largest size I've ever designed and installed. I don't even know what the next size would be. Is there a 1600A and a 2000A? If so I've never heard of them.
Let me know your thoughts on this subject please.
When they get that big, you usually have engineering support. Standard breaker sizes in article 240 are 1600 2000 2500 3000 4000
5000 6000 but there are bigger ones. I suppose you could dig out all the answers you need from the NEC but I have always been looking at engineered drawings when I see anything much over 800 amps. It was only a few times inspecting but in computer center design, 1600a or 2000a services were not unusual before computers got small.
From a few states to the east of you...
Larger than 1200 amp services are not uncommon here. First off, you should check with the local POCO to determine their restrictions on capacity at your requested voltage.
Our local POCO requires plans and specs before they will come out for a pre-con site meeting.
Here you would be required to submit plans, specs, cut sheets, and load calcs from a Licensed Design Professional, signed and sealed.
For instance, a 1.8M sq ft fulfilment center that requested 2x8000 amp, 277/480 volt services wound up doing primary 13.2KV with ALL equipment past the 13.2 KV feeder being customer owned and installed. That is except the metering equipment (PT/CTs).
4000 amp, 277/480 are the max our POCO can provide under "Normal" conditions.
If I were you, I would start with the POCO, after I prepared a preliminary load calc.