Be sure to read the tankless hot water heater thread. Lots of good information there about how bad they are for various reasons.
My 1,200 square foot house is home to two Model 3s, a Fiat 500e and a Cadillac ELR plug-in hybrid with three drivers. Our service is 125 amps and we get by just fine. We have two wall connectors sharing a 50 amp circuit and two other 30 amp circuits for car charging. Total charging load is just under 80 amps (40+24+15) since the Cadillac has a slow 3.3 kW charger. The main bottleneck is the wimpy 50 kVA transformer that feeds my house and six of my neighbors. Regardless, we have never had a problem getting a full charge on all of the cars overnight, even in the summer when neighborhood air conditioning loads are high and we have to throttle back the charging speeds to avoid unacceptable voltage drop.
What you’re proposing can be done with 200 amps. The cars don’t need to charge as fast as possible simultaneously and it’s unlikely that you’ll be fully replenishing the Tesla batteries every night.
My recommendation: install two wall connectors sharing a 60 amp circuit, then install two J1772 stations sharing a 50 amp circuit. The Teslas will charge at the full speed of 48 amps when charging individually or at 24 amps each when charging together. The other EVs will charge at 20 amps each when charging together, which is plenty of time to fully charge them in the overnight hours. Finally, look into a hybrid heat pump hot water heater. It will likely save you enough money on electricity to cover the power used by one of the vehicles.
My 1,200 square foot house is home to two Model 3s, a Fiat 500e and a Cadillac ELR plug-in hybrid with three drivers. Our service is 125 amps and we get by just fine. We have two wall connectors sharing a 50 amp circuit and two other 30 amp circuits for car charging. Total charging load is just under 80 amps (40+24+15) since the Cadillac has a slow 3.3 kW charger. The main bottleneck is the wimpy 50 kVA transformer that feeds my house and six of my neighbors. Regardless, we have never had a problem getting a full charge on all of the cars overnight, even in the summer when neighborhood air conditioning loads are high and we have to throttle back the charging speeds to avoid unacceptable voltage drop.
What you’re proposing can be done with 200 amps. The cars don’t need to charge as fast as possible simultaneously and it’s unlikely that you’ll be fully replenishing the Tesla batteries every night.
My recommendation: install two wall connectors sharing a 60 amp circuit, then install two J1772 stations sharing a 50 amp circuit. The Teslas will charge at the full speed of 48 amps when charging individually or at 24 amps each when charging together. The other EVs will charge at 20 amps each when charging together, which is plenty of time to fully charge them in the overnight hours. Finally, look into a hybrid heat pump hot water heater. It will likely save you enough money on electricity to cover the power used by one of the vehicles.
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