[manquer]

it is not a b/w choice between 100% solar or 100% oil, hybrid solutions could work and address the gaps solar/electric cannot handle,even 10-20% emission savings could mean a lot .

Also it doesn't have to be solar directly, an electric propulsion system which can use hydrogen or high density battery/ storage which plugs into the grid eventually is good enough.

You don't need to drag the cells with the ship, they could be perhaps stationary middle of the ocean and charge the replacement batteries and you could line few such charging stations near the major shipping lines.