Piping solar power directly to battery? Not feasible for multitude of reasons.
1. When the battery is off, i.e. , when the contactors are open, the leaf does not expect voltage on the HV side. If you were to pipe some solar power in the form of 400V to this place you will make the car think that there is a leak and it will shut down permanently, requiring Leafspy or dealership to clear the fault.
2. It is hard to reach 400V with solar. One panel usually has a Voc of 22V. You will have to put so many in series to reach 400V, and that wont fit on the car. You could add DC-DC boost converters, but that will increase the complexity dramatically.
3. How do you turn it off? You will need custom charge controllers that handle 400V. Otherwise the solar will overcharge the battery, and make it an extreme firehazard
Just use a Lead acid battery, an inverter, add solar panels to roof and charge from the inverter -> type1 car inlet. This way always works!