Star Harvester

Very Interesting but very important debate , this thread .
One cannot fault any argument provided , its up to you to rate the fuse as small as you possibly can , but in the defense of Justin Schoeman , I want to note the following :
1. A Fuse , even fast-blow is never designed to protect a silicon based subsystem from failure , because silicon (eg. Mosfet)  can and will will fail long before the Fuse will start disconnecting . In this regard the Inverter must look after itself , and its typically equipped with lightning fast current limiting circuits ,overvoltage crowbars and power limiting circuits. This is the primary line of defense .  In the same manner , the battery subsystem looks after itself , by means of the BMS . 
2. The Fuse is only there to prevent catastrophically thermal related failure in the 'plumbing' , when the electronic defense systems has now already failed. the plumbing  being the conductors , the connections , the PCB tracks etc. It will prevent thermal runaway (fire) , and it will prevent physical , mechanical damage to equipment .  This will typically allow a inverter PCB to be repaired , as opposed to throwing it away.
3. Therefore it is actually realistic to rate the fuse above the maximum margins of the function. Because we don't want the fuse to get ruptured during the windows where the inverter should protect itself. It leads to unnecessary spurious blow of fuse .
4. For these reasons , whenever a fuse blows , it must never be replaced without having a thorough investigation to the root of the problem. Never keep a fuse handy , do the investigation first. In case of doubt , consult  an expert.
Just my R0.02 
 
 

No, it's not required. Adding a CT only changes the point at which reverse flow is stopped. Without it, only things connected to the output of the inverter will be powered by the inverter or solar. By adding a CT, you are able to also export power up to where the CT is installed. For example, if your geyser is not on the output of the inverter, by placing the CT before the geyser, will allow the inverter to know how much power it uses. With that knowledge, it can "export" just enough power to power the geyser, without exporting to the grid. (It does require the grid to be present)

See the below as well from freedomwon, clarifying this matter 

The regulations are very clear, and the issue of creating a potential between 2 earths is very clear, do NOT do it.
There is Only one earth ! Repeat after me ! There is Only one earth
Lightening Protection System regulations and Solar Panel Grounding Regulations are completely different things, solar panels are not grounded for lightening protection and a 6mm square area wire is not up to the job of lightening protection which requires very large area down conductors 50mm square = 8mm diameter (here is where you all get confused, you see the 8mm and think area, some of you then put 10mm area cables in for lightning protection = WRONG the minimum area is 50 square mm and 2 down conductors for lightning protection, AGAIN, solar panel earthing is NOT for lightening protection.  
So lets stop pretending that a 6mm square area earth wire is going to afford ANY lightening protection, also lets not confuse surge protection MCBs (surge induced by lightening) with lightening protection systems either, surge MCBs clean the +VE and -VE power wires for DC, clean the LIVE wire for AC, the Neutral wire does not normally need to be cleaned for AC because we are TNC-S and Neutral is already earthed, unless you live on a farm with sub-db boards far away from the eskom point of control, you probably will never need to have 2-pole (1+N) AC surge protection, AGAIN Surge MCBs have nothing to do with the reason that solar panel chassis earth wiring is required it is a different 3rd subject area.
SANS NRS 97-2-1 regulations clearly specify when Earth spikes should be used and clearly specify that the earth spike should be connected to the Eskom Earth.
Gerrie is 100% right that NRS97-2-1 is the place to look.  B.3.2.2 specifies "not required" but "preferred" for embedded generators, this is expanded upon per system connection type in the connection diagrams at the end, it also specifies that if you use an earth electrode that 6mm is likely not enough for the connection to eskom, B.1.5.2 states that it must be at least HALF the area of the supply wires which are usually 16mm for domestic supply, so that means the COMPULSORY interconnect between the Earth Spike and Eskom is usually 10mm for 60A connections but may be 16mm for 80A connections  

Solarassistant does work on the 24v Axpert. Only display the info that is on the Axpert display. The 24v model does not display AC charging. Settings and monitoring can be done remote. The Raspberry pi is the main cost. The software was R800

If you are lucky and have a few grand then solar assistant may work for you. I'm not sure if they work with the 24V models and how well it works with clones, but it can connect to axperts and has its own wifi module and software built in. Ask them directly if you're interested.
@Star Harvester

It would seem it was in the UK and you know what they say, an Englishman's favourite two days of the year are Christmas and Summer...

Thanks Scorp, good to hear it is not required in practice. I came across this video where he points out there is in fact a leakage without diodes and shading but it seems small. Think it only becomes a problem when the voltage difference between strings is large.  If all the strings do not have the same amount of panels for instance or perhaps different panel sizes on different strings like on an RV or mobile type setup all feeding into one MPPT.