In terms of power / weight solar can already beat many IC engines.
The only thing more efficient solar brings is less packaging and use in extremely confined spaces like the roof of a car.
PS: The car thing should start taking off in a few years. A Tesla model 3 is 4.6 meters long 1.85 meters wide so 8.7 meters square. At 40% your talking about around 30kwh per day which could really extend the range and for less used cars minimize recharging.
The only thing more efficient solar brings is less packaging and use in extremely confined spaces like the roof of a car.
PS: The car thing should start taking off in a few years. A Tesla model 3 is 4.6 meters long 1.85 meters wide so 8.7 meters square. At 40% your talking about around 30kwh per day which could really extend the range and for less used cars minimize recharging.