Here's some available solution of Hartshorne's GTM 52, Chapter 1:
https://math.berkeley.edu/~ceur/notes_pdf/Eur_HartshorneNotes.pdf
Ch1-5, part
https://math.berkeley.edu/~reb/courses/256A/
Ch1 and part of Ch4
I found a collection of solutions on github but it seems that it is invalid now. But I think I can always count on mathstackexchange ;)