I only drive the Roadster a handful of times each month and won't ever need it to recharge quickly, so is there any reason to not leave it plugged into a standard 120v wall outlet charging at 15amps? Are there any drawbacks to using this method rather than having an electrician install a 220v outlet for the sole purpose of having the car plugged in long-term for essentially the same level/rate of charge as the 120v outlet?