Welcome!
I have no experience (nor want to) in commercial brewing - but this might help with setting up a 15 gallon brewery.
I can brew up to 15 gallon batches on my system - 50L mash tun (RIMS), 100L boil kettle (which doubles for heating mash and sparge water). You wouldn't be able to go much smaller than that. All electric, you need at least 4 to 5kW to handle that size batch. That can be an issue with 110V. It would use a lot of gas to direct fire a 15 gallons system.
Some questions for you to decide are:
Off the shelf brewery (expensive, convenient) vs build yourself (cheaper, fun (maybe), more work).
3v (or more?) vs single vessel (eg. BIAB).
Temperature control - how? 15 gallon of fermenting beer produces a lot of heat - you will need to control it.
Fermenters - expensive conicals vs plastic vs other.
Lots more - the point being that there's a lot to think about other than the brewing system itself.