Lourens1975

Good evening @Lourens1975
It all depends where the inverters are installed and where the Main DB is located and what environment the wire or wires or cable or cables are exposed to, also remember that with inverters running in parallel it is always better to have the cable protection for the inverters output as close to the inverter as possible and it is advisable to have an Isolator as well as a MCB for each inverter output in a single DB.
If the cable protection for each inverter's output is in a single DB then there is no problem later on if you want to run 1 or 2 thick wires or cables from the DB to the Main DB or separate wires or cables for each inverter to the Main DB. If 1 or 2 thick wires or cables are run from the DB to the Main DB then the outputs of the MCB's can be combined and fed to the outgoing wires or cables.
I distinguish between wire and cable because a cable consists out of multiple wires and it is important to know the difference. Loose wires that are used in the wiring of a premises are called GP Wire, Surfix and Twin and Earth are made up out of GP Wire and therefore it is a Cable and then you get SWA - Steel Wire Armoured which is also made up out of GP Wire so that is also a cable. The operating environment for each of these above mentioned types of wire and cable are different.

Kind Regards
GerhardK83

Lite-Glo in JHB
16mm2 - R56.50 p/m
https://www.liteglo.co.za/product-category/general-purpose-house-wire-per-meter/page/2/
I buy from them all the time and I am in Cpt :)
Best prices and quick reliable delivery.

My advice is do a regular check not just after a short period. Due to the high current on the battery cables it is a quick check to do say every 3 months.
There is a lot of expansion and contraction that can cause loose connections.
As @frivan mentioned I have seen up to 80 deg C even on the PVC around the load terminals in the bottom portion on the DC MCB on a battery circuit. Terminals were tight.

Make sure all wire connection terminals are well tightened. Loose terminals with high current can heath up and the effect is worse with DC than with AC.
Also take in account that common circuit breakers are designed for AC. Their capability to break DC is limited to lower voltage. A not extinguished arc in a tripped breaker can put fire to the PV Combiner Box.

Also check your Frequency setting on the inverter.
Make sure it is on 50Hz

Nothing that Eskom provides is the best. Typically the neutral to earth connection at your supply point should be competent. If you want to have multiple earth rods, I would connect them all.
If your inverter will be your main supply, I would connect earth and neutral inside the inverter. Earth leakage units downstream require this but units upstream will trip.

20 x 5 mm copper busbar can carry 274 amps at 30°C
https://www.em.co.za/BRF1015?srsltid=AfmBOorYF8xiMaO9B35Xk7XuWaNeW7x_6J1zWADiboIbEFKK1CE10Ure

If I understand correctly, I'll be fine with 250A busbars. Awesome. Thanks guys, much appreciated.

I think I got the problem sorted this afternoon. The BLC Setting is not mentioned in the manual. It was set at 20A. I set it up to 50A, and voila. Everything works. Seems like it comes factory at 20A. 
Not sure what the correct setting should be.
 
Thanks for all your help. Much appreciated.