The species epithet sol, derived from the Latin word for "sun", was chosen to reflect the rich yellow colour of its often circular thalli, and its preference for growing on dry, sun-exposed rocks.

Its areoles are usually thicker and strongly convex near the shore, but those found above the splash zone may resemble F. sol more closely, presenting challenges in distinguishing individual specimens based solely on morphology.

[1] Flavoplaca maritima differs from F. sol in its more convex areoles that tend to become isolated as the thallus ages, and its young apothecia often feature a yellow crenulate thalline margin.

Xanthocarpia diffusa, typically found on damp or poorly drained surfaces and not in coastal habitats in Great Britain, has a less developed epilithic thallus and ascospores with a much narrower septum.

Finally, Athallia vitellinula, as defined by Ulf Arup, is a non-maritime species characterised by a thin, inconspicuous, discontinuous pale yellow thallus, and small apothecia up to 0.44 mm in diameter in British specimens.