most charging stations run between 40-50 amps (ones that i have installed). the cars charge for something like 8 continuous hours. correct me if im wrong, but most home solar arrays barely put out 50 amps of power during the daytine, and certainly not at night. you cant store enough batteries to supply 50 amp draw for 8 hours to charge your car at night. at least not in the systems that i have worked on.
You may want to put an Amprobe on while charging -- typically we see them only running about 30 amps on the rated 50 Amp circuit.
But as to your math -- you are sort of correct, but have your "story problem" of it set up wrong. That 8 hour night of charging -- at 30 to 40 amps -- is going to produce about a weeks worth (around 300 miles) of driving. So consider, you are (sort of) figuring this is what happens EVERY night -- when for most EV drivers, this would only be a once a week (or maybe less) occurrence to fully charge a Tesla scale battery from "empty" to "full." That would mean your observed guessimating is off by a factor of 7X.
But to avoid all that mistake modeling, it is generally better to step out of "Power" modeling (Volts x Amps = Watts, right?) and instead view this as an "Energy" model (Watts x Hours = Watthours).
So doing this as an Energy or Watthour Problem: Typical EVs take about 250 Watthours per mile. (Typical for Tesla, or my Volt). And say we were going to drive 40 miles per day? That would mean we would use about 250 Watthours X 40 Miles = 10,000 Watthours, or more commonly expressed -- 10 kWh. (We good on that part?)
Now let's look at the Solar Array? Typical house sized array might be 10,000 Watts, or 10kW. And average run-time in the US, it may have a 6 hour production day. (anyone can change those numbers for your size system and locale). 10,000 Watts X 6 hours = 60,000 Watthours, or about 60 kWh. So that leaves us with 50kWh for the house, and 10kWh for the EV -- and that about covers most real-world drivers and scenarios. We could probably Net-Zero a typical house and driver in that scenario.
Now on the day we may drive the Tesla 300 miles -- it will take about 250 Watthours X 300 miles = 75,000 Watthours or about 75 kWh -- so to go 300 miles would use more than the 10kW Solar Array produced for the day, however, the Solar PV would offset most of the EV long-distance use.