Craig1970

Hi Markus, yip, you are correct. I climbed into the roof and replaced the extension by simply splicing in a 5m length of 1mm Cabtyre (I had no network cable around). Voila, it works perfectly in that location. To confirm my suspicions, I took the "dodgy" sensor cable to another THR on opposite end of home and subject to more interference, and it did exactly the same (cutting between 31-36 deg). If I remove the OEM extension the sensor works perfectly on it's 0.5m cable.
It is beyond logic that the OEM extension cable caused specific range failures on 3 out of 3 extension cables, but that is what I have found. I do not suggest anyone buy these RL560 5m extenders, if they want to use full range of sensor. My suspicion is the wire is too thin (thinner than sensor cable) and/or subject to interference.
Thanks again Markus, hope Sonoff upgrade this RL560 product and remove existing stocks. 

Had same issue on my own extension cable...blanked out between roughly 28deg and 42deg....
Extension was made up of good quality UTP cable, about 15m. 
Tried many tricks to fix this, and what eventually did it was changing to STP cable! Seems the cable needs the shielding...
@Muchachos you did mention using an extension although it sounds like the original Sonoff extension? Weird, that should work..how many meters you extending?

Summary of findings/testing of Sunsynk 8.8kW using Aux Circuit for load shedding.
I put together the attached doc to save future buyers like me having to spend so long in finding out what should be explained in user manual, as well as installer manual.
Thanks @Achmat and @Johann1982 for your assistance and patience.
Hope this is of assistance. 
                        Sunsynk Aux Circuit.pdf    

Summary of findings/testing of Sunsynk 8.8kW using Aux Circuit for load shedding.
I put together the attached doc to save future buyers like me having to spend so long in finding out what should be explained in user manual, as well as installer manual.
Thanks @Achmat and @Johann1982 for your assistance and patience.
Hope this is of assistance. 
                        Sunsynk Aux Circuit.pdf    

No problem. 
Figures above are for the 8kw inverter. Can't recall which one your have. I have the 8kw so default to using it in my examples. 

Hi. 
Yes. If the loads are met from available pv, any excess up to the limit will go to the aux if the grid is down. You can power the aux loads at night if the grid is down and the SOC is higher than the aux off battery setting. 

I don't have the neutral earth bond relay. Everything I've read indicates that it's not compulsory and only needed if you have a floating neutral. My whole house is on the inverter which I think eliminates some of the need for the earth bond. 

Yes, no more restarting issues. Everything is running smoothly.