Interesting thought experiment. It's usually positioned as how much area of solar panels are required to move a train.

At the moment, it seems impossible to build an electric container ship to replace current shipping methods. The goal has moved to building smaller electric boats with batteries that get swapped out at the port. They also make more stops than current ships, which presents an interesting problem with shipping queues at ports...

Panamax style ships have engines about 80 MW in size. Crudely, the batteries required for the duration of the voyage would weigh more than the carrying capacity of the boat. Batteries are really inefficient with poor energy density when compared to almost any liquid/gas fuel.

On-board generation of even 5% of that required energy is 400kW. Plug that into any calculator for roof top solar and you will find the area required is massive.

You also want the solar panel to be angled correctly towards the sun. That's going to decrease the solar efficiency even further. For instance, your sail is probably going to be positioned roughly vertically, instead of the more ideal angled towards the sun or position on a tracking system to orient to the best angle.