Wikia

Solar sailers were a method of propulsion used by some starships. Although called "solar" sailers, they were more commonly propelled by tachyon streams and ultraviolet lasers rather than the photons and "solar wind" (high-energy plasma which escapes a star's gravity) of sunlight. Gathered on a sufficiently large surface (solar sails would unfurl to colossal diameters, rivaling the surface area of moons), the absorbed momentum would then accelerate the spacecraft. Once optimal acceleration has been reached, the hyperdrive motivator would kick in and allow the craft to enter hyperspace.^[1]

While cheap and easy to produce, solar sails were not widely used as a propulsion system, for three main reasons: the first is that the sail is at its most efficient when traveling close and directly away from a star. Solar wind and photons are only exploitable in the general vicinity of a star, and changing directions would imply either the use of gravity from a nearby stellar object, or the inclination of the whole sail. The second reason is the sail's size: even a small ship would require a very large sail to be accelerated to hyperspace entry velocity, thus increasing the overall ship's size. this can be averted to a point by storing the sail away when not in use. The third reason is that the sail is rather fragile: micrometeorites and random stellar debris can very quickly and irremediably shred a solar sail to the point of uselessness.^[source?]

A major advantage of the solar sail, however, is that since it uses no on-board fuel, it leaves no readily identifiable residues, and it's passage is virtually undetectable once the ship has departed.

Count Dooku had a one-of-a-kind solar sail procured from the Gree Enclave fitted to his Punworcca 116-class interstellar sloop, which he used as his personal transport prior to and during the Clone Wars. Very small for a sailer, with a sail of exotic matter powered by mysterious undetectable energies, Dooku's interstellar sloop was one of the most unique craft in the galaxy.^[1]