My take on EV panels is that IF you can charge while they are outputting their max, you need to determine what your baseline load is, and how much excess you could be sending back to the grid. That's the ideal size of your EVSE. If you only recharge at night, it really doesn't matter since you're using borrowed energy from the grid, or from your storage bank (which would need to be bigger by the nominal load).
The i3 can handle 7400W at any one time. It tapers off the demand as the battery approaches max, and may start out slower if the battery is too hot at the beginning, using some energy to cool them first.
7400/240=30.83A at that rate, it would take about 3.5h to recharge a nearly depleted i3 battery. FWIW, my normal line voltage is averaging 245VAC, so 245*30=7350, or essentially at full rate. European specs are peak, the US specs are average, so a 30A USA spec is essentially equivalent to a 32A European unit.
The i3's battery lets you use nearly 19Kw of power, and the recharging circuit is not 100% efficient and it may need to cool things in the process, so you need to put in more power than the battery actually stores...for rough numbers, figure maybe 20Kw.
So, your answer really depends on how many watts you can use at any one time, and how many you need to refill the battery. Taking our 20,000W/7400W max gives you 2.7 hours. But, it does not use the EVSE's maximum output the whole time, so that's why they say around 3.5 hours.
A 20A unit with 240vac input produces 4800W. If your voltage was 230V, 20*230=4600W, 220v, 20*220=4400W. Many EVSE websites have charts for typical vehicles, but you can figure it out for yourself.
Power=volts*amps, and the max the i3 can use is 7400. Anything less, slower recharging rates. Note, a smaller output may not take quite as long as may first be inferred because charging at a lower rate means less heat and therefore cooling, but given that it must occur longer, not much. Depends somewhat on ambient. THe difference may not be as great as it first appears because of that fact.