My main breaker is 100A. I understand my electrician can do load calculations for a charger, I'm thinking of getting the Model 3 Standard Range Plus so I would only need the 40A breaker. My main panel is an older 100A breaker, but assuming 40A will be too much load with the rest of my breakers, is there any other options I'll have available other than an entire new 200A breaker or less amperage breaker for the charger?