Hooking up a 24 V panel, capable of 30V with no regulator, diretly to a 12V battery, should be enough info. Someone tries this on an expensive AGM or Surret or Rolls battery, because they read it here, and they're not going to be happy with the results or the replacement cost. And any other electrical equipment that gets roasted along the way.
No personal vendetta, just saying, check for reasonableness.
Thought process like above leads to "Well, I put a 24v panel on a 12bv system, why not just put 240V into my 120V system, it worked the last time." Folks, don't do this, at home, or on your rig.
Unless you truly know what you are doing... not a good idea to try and adapt a 24v system to a 12v system, unless you lay out the caveats and risk and a release form. IMHO, I see it as bad form. Keep 12v 12v and 24v systems 24v. The average laymen around here could really get in a pickle when seeds like these are planted outside the lab or folks that don't have the EE backround start mixing and matching.