I have been trying to get broken hero swords for the terra blade.
This is a screenshot of my solar "farm" from my Steam Screenshots:
It is not AFK, but it is a lot of waiting mostly. The mother slimes sometimes break into slime-lings through the wall and can get annoying.
Now that 1.3 is here, you can trigger the Solar Eclipse at will, like most other events.
After you have gotten access to the temple inside the jungle, you can farm solar shards to create solar tables. Use eight shards on a Mythril/Orichalcum anvil to craft a tablet; the shards drop randomly from the temple enemies.
You can use the Tablet on daytime to trigger a Solar Eclipse. That should let you farm the event much more frequently.