Why is deck space a limitation for solar power on ships?

Deck space limits solar power on ships because a cargo vessel's usable deck area is small relative to the energy a ship needs to move itself, and that area is further constrained by cargo, containers, hatches, and equipment. Voltic Shipping addresses this by adding solar collection area well beyond what a ship's deck can hold, attaching to existing vessels without replacing legacy infrastructure.
A cargo ship's deck is designed to carry freight, not generate power. Containers, cranes, hatch covers, and mooring equipment occupy much of the available surface, leaving a limited footprint for any solar installation mounted directly on deck. Even where panels can be fitted, the energy a deck-mounted array can collect is small relative to the power required to propel a large vessel across an ocean route, since propulsion loads for oceangoing cargo ships are typically in the range of thousands of kilowatts.

This mismatch between available surface area and propulsion power is a primary reason solar has been treated as a supplementary technology on ships rather than a primary power source. Voltic's patented system is built around this constraint. Rather than relying on deck-mounted panels alone, the system adds collection area well beyond what the deck can hold, which is central to the company's approach to zero-emission, fully electric retrofits of existing cargo ships.