Using the Solar to run an exhaust fan, or other 12v accessories is a decent idea.

Charging the HV Battery via the "jump start button" will NOT work.
( tried that the second week I owned my vehicle, as I also have 75 watts of solar panels just lying around, working my garden lights right now... )

The HV jump start button only works when your HV battery is below 40% and so low it won't start the car. Once the HV battery has even the bare minimum, the jump start button is disabled. You're going to need a very sophisticated hack involving computer programing to pull this one off.

There is some documentation that the "jump start button" simply heats the HV cells, giving them a voltage boost in borderline conditions, but does not actually provide a direct charge, and won't resurect a deeply discharged HV pack.

-John