hellfire

Values marked R/W in the Sunsynk Modbus reference document can be written to and changed. 
Not sure what value is the one to enable priority load though. 
I took all the Chinese out of the original document that I had to make it easier to read, have uploaded a version for you 
 
 
sunsynk_modbus - no chinese.docx

Just thought I'd post an update on using the CBI Astute with Home Assistant. I have it working without having to Tasmotize it or open it or do anything silly to it.
I ignored the CBI app and simply added it using the Tuya Smart app. BUT, it didn't seem to like auto-pairing with my phone. (I ended up trying it with CBI app as well to troubleshoot and it didn't work there either). 
What I ended up doing was putting the Astute in AP mode (which doesn't appear to be documented) by holding the power down for 5 secs to put into normal pairing mode, and then holding it down again to put it AP mode (it will slow flash the blue light instead), then add manually in Tuya Smart, I just chose Others (wifi), follow the prompts, connect to the AP (which was SmartLife-2701 for me) and boom! Shows up as ASC (Wifi) with CBI logos and backgrounds in all the right places, with the power monitoring working correctly. 
As for home assistant I haven't gone any further that using the built Tuya integration which only shows it as a switch, but there is something else on HACS called Local Tuya which allows full customisation including power monitoring. I haven't gone down that rabbit-hole yet because it's time for beer.

Yes, only essential adds to overload.

Excellent solution. Now you also future-proof👍
Show us images when you done, for the benefit of others that also need to address legacy issues. 

After pricing main switches, earth leakages, DIN rails etc, it actually worked out cheaper to buy a pre-populated Veti DB which I'll fit into the cavity in the wall, and then make a nice frame to cover the gaps thereafter.

After pricing main switches, earth leakages, DIN rails etc, it actually worked out cheaper to buy a pre-populated Veti DB which I'll fit into the cavity in the wall, and then make a nice frame to cover the gaps thereafter.

After pricing main switches, earth leakages, DIN rails etc, it actually worked out cheaper to buy a pre-populated Veti DB which I'll fit into the cavity in the wall, and then make a nice frame to cover the gaps thereafter.

After pricing main switches, earth leakages, DIN rails etc, it actually worked out cheaper to buy a pre-populated Veti DB which I'll fit into the cavity in the wall, and then make a nice frame to cover the gaps thereafter.

Ah apologies I am may be confused my self. But the smart load shedder can just switch on and off via a wireless signal.
 
But if the power to the valves comes from the gate motor, then you can use the Eskom power at the gate motor to then control a contactor which would switch the 12V DC valve cable on and off, bascially then a wired switch.
 
The valve cable would be wired through the NO or NC terminals and then the A1 and A2 (coil) is then powered by the 230V Eskom supply.
 
So when Eskom on the valve off and and when Eskom off then the valve on. (or what ever variation you require)