RWI

Hi, this is a grid tie inverter and there is no switching (confirm this by checking the grid V and the load V which will be the same) except when it disconnects form the grid because the grid has failed. On mine when the minimum SOC is reached it slowly transfers the load from the battery to the grid (i.e. just reduces the inverter power). Maybe it is a setting issue. Are you zero export to load or zero export to CT. My system regularly switches on and off a 2hp water pump and there is no "flickering" even when disconnected from the grid. I am impressed with the performance of this inverter. Are you sure that it is not disconnecting from the grid and re-connecting because it reaches one of the Hz or V limits in the grid settings. Really should not do this unless you have a really weak grid connection.

This is a complex issue with many different opinions and experiences. I do not intend to get into an esoteric discussion on this Forum.

ELCBs are old type voltage devices and are not generally used now. The safety protection devices used in domestic installations and other places today are RCD/RCCB and are current devices. They measure the current difference between the two wires supplying the device and trip if this is more than a certain value typically 30 mA for domestic installations. They will therefore work even if there is a high impedance between N and E (not good ground) and if there is no connection at all it is not technically unsafe if one wire is connected to ground unintentionally (fully floating system). A good N to E connection is however required to trip on earth fault unless you have an IT system (very high impedance earth) used in parts of Europe. The important thing is that if the system is designed for a hard connection between N and E then this is always maintained preferably by passive means and not relying on actuated devices.

I am not directly familiar with your system but I believe that South Africa implements the Terre-Neutral-Combined-Separated earthing system TNC-S in which the neutral and protective earth conductors are combined on the utility side but separated on the customer side (see attached). Your diagrams appear to confirm this. If this is the case then you probably don't have your own earth system with earth stakes and all earths are connected to the incoming supply earth only. Hence if you install a relay to connect N to E on the islanded load side of the inverters you are in fact connecting the Ns together through the earth system. It would be the same situation on the diagram provided by PowerUser unless you wanted the UPS power to be floating. In some similar TNC-S systems such as Australia and NZ they have a MEN (multiple earth to neutral) addition where a local earth system can also be connected to the neutral giving multiple earth to neutral connections. I had a quick look at your standards to see if there was anything on solar systems and it appears that this is in draft from at the moment. I have however attached the diagrams from the draft which show the neutrals all connected together. Hope that this is of some help.

Hi, I have the same setup with two Deye 8 Kw in parallel. You need to connect the N of the Inverter load output to your N bar. When you are grid connected this is the N passed through to the load. Hence the N is identical when you lose the grid and you are not floating. The only problem with this is if you isolate the incoming neutral from the neutral bar with for instance a 2 pole incoming breaker that you open for maintenance then you are floating again if you are operating in island mode. If this is possible then one option is a local E system with earth stakes and link this E bar to the N bar (normally you would have your own earth system). If you don't have an earth system are are certain that the E from the supply is good and never disconnected then you could connect this to your N bar which is referred to as a MEN (multiple earth to neutral) system. Hope that this helps. Of course you need to check your local regulations for compliance but these usually do not envisage a potential isolated internal solar generation system. The Deye inverters do have an output to operate a relay in island mode that you use to connect the N of the inverter load to E but of course this is an active and not a passive system and less reliable.