martinmcg

For the record, the resolution to this problem was a firmware update from Segen Solar. Rather frustrating waste of time.
Thank you all for your help.
I (foolishly) assumed that on checking their firmware upgrade site was out of action that they would at least be shipping new inverters up to date or close to.
As a btw: When we tried the solar panel test, not sure what went wrong but when we flipped the fuse off it failed/caught fire.
 

Four panels might be too low for this model to get started. Although the MPPT range is  given as 120-450 VDC, it doesn't say what the start voltage is. It's often a bit higher than the minimum MPPT voltage, say 150 V±5 V. Your panels are showing around 167-183 V, but under load they may sag to around 152 V. If the starting voltage is at the upper end, say 155 V, they might not have enough voltage under load to reliably start the solar charger.
It seems unlikely, but possible.

There is 1 test you can do to rule out the solar array(4panels). You have already done the Voc test on the array by switching the breaker off and measuring the voltage. Now this part you need to take care and use the correct isolator. Isolator rated not less than 250v DC 20A DC. Bridge the top and bottom contacts on the isolator then disconnect the pos and neg from the mppt. One wire to the top of the isolator and the other wire to the bottom. You will need a dc clamp meter to measure the Isc of the panels the reading in good sunlight need to be around 13A but should you get a slightly lower reading do not worry the important part is that current reading needs to be consistent and close to 13A(depending on solar irradiance)as possible. Should you take a voltage reading across the isolator the voltage will be 0v or close to it. Should the current not be consistent you have a bad or loose connection on one of the mc4 connectors or in the combiner.

There could be several problems causing the charge controller to switch on and off:
1. Faulty charge controller.
2. Earth fault on one of the 4 panels.
3. Loose connection on mc4 connector or on the combiner.
As soon as the panels start delivering current the charge controller switch off hence the reason for the fluctuating voltage. I once had a Sunsynk 8kw that   would not switch on any of the mppt's even with adequate voltage from the string, after investigation found 1 panel in west facing string was leaking dc to earth and the inverter detected the earth fault.

Its the protection diode before the voltage measuring circuit.  May be bad soldering too

Here I cannot help as your PV exceeds 7kW and during cloudedge the panels might produce over 8kW for a moment. Also with only 1XMPPT the specs give 18A max. You intend wiring panels that might give up to about 13A per string. 
I have never seen the allowed 1.2 that so many people indicate as acceptable but should something fail this can be used as abuse of the inverter. 
This risk is on you. 

Answer for 1.
The 80A is in total as there is only 1 battery connection. This can be max 80A from AC or 80A from PV. Also 80A in total if you combine AC and PV. You are right although a 8kW inverter to provide AC but charging is up to 18A 450V to about 8kW from 1 MPPT. You can use both MPPTs for a total of 8kW. Only 80A can go to the battery.(4kW) The rest is for using to power loads. 
Answer for 2.
It normally needs 150V to start operation. After that it can drop no lower than 120V to continue operating from PV. 
3.  
AFAIK the WiFi is remote via the APP. As long as the inverter has WiFi and you have Internet on your phone you can see the levels on your phone in order to act.