Don't guess. Fixing something that isn't broken gets expensive.
It could be any of your DC sources which means your solar charger, your battery charger or your alternator that is causing the over voltage.
Disconnect two out of three of your DC sources. Turn on the remaining DC source and put a good digital multimeter across your DC system where your battery got destroyed. Do this with a new battery in its place. Watch the voltage when your DC source is charging. It should never get much over 14 volts. Test your other DC sources in the same way, by turning off or disconnecting all but one DC source.
This way you can nail down which is the problem child without guessing.
Once you have determined which DC source is the problem, you may need to replace the regulator for that source. Before you replace the regulator, make sure all your electrical
connections are clean and tight, especially any voltage sensor wires.