Not everyone has the same amount of sunshine as large swathes of Australia.
=======================
At the Tropic of Cancer, for example:
To recharge a Model 3 from empty in one sunny day: about 17–18 kW of portable PV.
Panel area needed: about 73–88 m² depending on module efficiency, with ~80 m² as a good midpoint.
(This is a very large trailer-sized or campsite-sized array, not a casual fold-out kit.)
For enough solar to replace one normal day of driving in one day, 40 miles/day at 25.4 kWh/100 mi is about 10.2 kWh/day, which would take about 2.2 kW.
One-day full recharge from solar alone is possible in principle, but it takes roughly an 80 m², 17–18 kW portable array. One-day replacement of normal daily driving is much more realistic, at roughly 2–3 kW.