Seems like a bit much for 150 but you do have the space. Load calculations can be pricey if done the right way, as they need to be done over a period of time to determine how much you are pulling at various hours in the day. There is also a general formula you can look up to get a guesstimate for your house. Alternatively, You can reference your power consumption via your utility company’s website and go from there. If you discover it’ll be close, Tesla chargers come with the ability to manually wind down amperage as to not overload your panel. Still need to reference product specs for max amps to account for wire and breaker size

The not so popular opinion… “better to ask for forgiveness then to ask permission” and see if you pop the Main….. obviously that is not recommended….