Student pilot and Instructor reported a runway excursion during first solo flight.

Report 1 | Narrative: This is my student pilot first SOLO; I practiced left closed traffic runway 27L. After landing everything is good enough. I thought the aircraft has been slowed down enough; then I want to off runway 27L at taxiway B to save space for the flowing traffic. But the velocity of the plane still fast; the taxi radius of the track is larger. Finally I skid off the runway and taxiway; rush into the grass area and hit one of the sign of the airport.

Report 2 | Narrative: All landings were completed on runway 27L. First attempted landing was a go around. Second landing was a stable approach for touch and go. Third landing was a good landing with a full stop taxi back; exit at taxiway Alpha. Fourth landing was a good landing with a full stop taxi back; exit at Alpha. Student pilot taxied instructor to admin building at SEE. Student pilot was doing his first solo. Student pilot made left traffic for runway 27 L. Student pilot made a safe and stable approach to runway 27L. Student pilot landed on runway 27L. Student pilot tried to exit at taxiway Bravo too quickly.

Student pilot did not slow down enough and ended up into the grass/dirt striking runway/taxiway sign. Student pilot ended up between taxiway Alpha; Delta/Runway 35. Aircraft sustained minor crease/scratch.

Report 1 | Synopsis: Student pilot and Instructor reported a runway excursion during first solo flight.