Solar souls are fighters. Monks who did not want sit peacefully and achieve Nirvana, but monks who want to stop evil no matter the cost. and with their techniques thy can do just that

Radiant fist

When you choose this archetype at the third level you gain the spell Sacred flame, in addition, whenever you cast sacred flame within five feet of your target it takes 1d4 extra radiant damage

Solar step

At the beginning of level six you gain access to the spell Flame stride, in addition, once you reach the 7th level, this spell does an extra 1d4 radiant damage 

Body of the sun

At the beginning of your 10th level you gain the spell Investiture of Flame, in addition, if you use it on a demon, undead, or aberration, you do an extra 2d4 radiant damage

  

Fury of the sun

At the beginning of the 14th level you gain the spell flame strike, in addition if you cast this against a creature of the chaotic evil alignment, they take an extra 1d4 radiant dmg