My experience sailing and dealing with vessels from 30ft to 180ft give me a perspective that you probably don’t.
Providing solar panels along the roof would give the ship a few KWh of power that would otherwise be drawing from the main batteries. This would extend the range of the ship by 5-10%.
The ship battery is 40,000 kwh and uses at least 10,000 kwh per crossing, with 10 minutes to recharge. A handful of kwh are negligible because this isn't a sailboat.
The electricity sector in Uruguay has 98% renewable power
The math has been done many times for solar panels on the roof of cars, and it's not worthwhile. Ships are not the same though.
At any rate, it's inevitably far more sensible to put a larger solar panel + battery installation at a fixed place on land, and charge vehicles from that.