bus bar thermal breakers - necessary?

[sunrise]

Hi folks,
In the 12v panel box of my trailer there is this positive bus bar - see the attached picture, it's the copper one on left side. I am wondering what's the purpose of the thermal breakers built into the positive busbar? more specifically, around what temp would they trip? would it be redundant(not saying it's a bad thing) when circuit already protected by current breaker/fuses? Are they intended to catch under gauged wire usage? or poor connection contact?
Asking as I need to expand the connections for solar and a couple of 12 outlet. I am considering adding an extension with heavy gauge copper bar but without the thermal breakers. I don't know what implication would be. I usually use over gauged wires and I do use laser temp gun to make sure nothing is getting unexpectedly hot.

 

[grizzzman]

Looks like self resetting circuit breakers to me. And yes heat due to overload triggers them. Commonly used in RV's. Also unless your your solar set-up is small it is best to connect at the battery.

 

[HRTKD]

I agree on those being self resetting breakers. I have none of those in my trailer. Maybe because that was not a standard back in 2006? I do have a bunch of fuses.

Your solar setup shouldn't need to directly involve this box. A configuration that is commonly used is this:

Battery (neg) -> shunt -> common bus bar (neg)
Battery (pos) -> fuse -> switch -> common bus bar (pos)

Everything that currently connects to your battery terminals would be switched to the common bus bars. All your new loads and sources would also connect to the same common bus bars. This is a significant change for most trailers. If you're not changing the battery to LiFePO4 and you're keeping the existing lead acid battery, then just run the solar controller directly to the battery terminals. That's how my first solar setup was done.