Pieke

System is running in solar/battery/utility mode. Line mode only is used if batteries are lower then 30% at 8H in the morning. Batteries are never charged by grid. If battery state of charge is below 20% whole system changes automatically to grid, just as safety measure. Even in SBU with ac in connected, although not used, i get these strange measurements. Disconnecting ac in everything is fine. So connecting ac in regardless of using it, changes the behaviour of earth and neutral. Using the grid only with no connection to solar system earth is ok, resistance is below 30 ohm, measuments made by digital earth tester.

After a lot of research i found some answers? When inverters are connected in battery mode without ac in connected the inverters are bounding neutral to earth, so everything is working ok. Ac out acts normal, result rcd's on my mains working fine. If i connect ac in somehow the bond between neutral and earth disappears and i get these strange voltages. And the rcd's on my mains are not working due to these strange voltages, this is a dangerous situation. So is there a way to establish this connecting between neutral and earth automatically only when ac in is activated? Is this a solution to my problem? What would happen if the inverters are going into line mode?

Both inverters, axpert king, are not in eco mode. I do this in a different way, that is the inverters are switched off the load automatically when batteries are to low, the grid takes over till batteries are at least 50%. This switch between solar and grid has a delay of 2 seconds and is commanded by a raspberry pi with home assistant. I only need the ac in in case i have to charge the batteries due to a long period without sun!

Your right, the monitor software says 110V and on the panel is indicated 230v of the inverter connected to the grid. So i measured between ac in neutral and ac out neutral of the inverter which is only one connected to grid. There i measure around 5V. Same value when i connect the other inverter to the grid and disconnect the first one. But now the stange part when i connect both inverters to the grid i measure a value of 95V? With both inverters disconnected from the grid the value measured is 3.3V, this should be 0V i guess.

in france utility is 230V, so rather strange when one inverter is connected to the grid and the other not, the grid voltage on the inverter is indicated as 110V. With both inverters connected 230V indicated, but neutral not 0V. Still don't know why this happens? The worrying thing is that the rcd's are not working on the load side when inverters connected to the grid because this.

Thanks all for your answers, could not respons earlier. @coulomb is right, i measure between output and input neutrals 89V. Could this be a malfunction between both inverters in parallel. I noticed also that when i only connect one inverter to the grid the input voltage is around 110V, and therefore no current taken from the grid! What would happen if you take out the parallel sytem and seperate them in two different output systems?

I do have also two axpert kings in parallel. Depending on what batteries you have the master inverter, with pylontech batteries, adjustment number 5 should be on PYL. And the slave inverter should be on user, not on PYL.

These measurements i get in line mode when grid is attached. Even when grid is not used but attached i get the same measurements. In battery mode without grid connection everything is fine. As i understood in France the bonding between neutral and earth is made by the electricity company, before electricity entering the premises. And like many other countries it is forbidden to bond the neutral and earth.

For me this did the trick, using the port A/CAN. Before i did not see my two stacks of pylontech batteries! You always can give it a try.

Thanks for your answers. When inverter not connected i measure between neutral and earth 2.4V. Would this be to high? Should i make a connection beween neutral and earth on the grid side? Or could this be a earth problem? I try to find a solution to have a solar system turning worry free fully automatically, which is not the case till now. AC in two inverters in parallel, i have a little but to high leakage current sometimes which is tripping rcd grid to inverters. So i mounted a isolation transformer to solve this problem. Sometimes, let's say once a two weeks, the grid is unstable. Result tripping interrupters ac in duy to low voltage. So in summer time enough energy, no grid connection. In winter time i want to leave grid connection on, when battery low automatically grid connection will be established. Not to charge the battery but just for the loads. When at home no problem, a reset is easily done. When away it would be nice to have a system 100% reliable

The task you want to do with your solar system is easy to with a raspberry pi with home assistant or with a homey. On both you can implement your axpert kings like i a did. With some zigbee interrupters you can easily control every household machine like airco, washing machine etc. With flows or actions you can decide when and on what conditions they should turn with a certain delay etc. Zigbee switches can also switch between grid and solar power instead of the axpert kings doing that for you. In that way you can add rather easy your own conditions depending on solar power, battery percentage, solar power dayproduction etc.

In my solar system i do have 2 axpert kings 5 kva in parallel. When the grid is not connected to the inverters i measure between live line and nul line 230V, and also between live and ground 230V, and between nul line and ground 0V. Result RCD's on load side working fine. When i connect the grid towards both inverters i measure bewteen live and nul 230V, between live and ground 138V, between nul and ground 92V. Result RCD's on load side not working! Does anyone recognize this problem and is there a solution? In my system there is no where any connection between output inverters and grid, these are fully seperated.

On your battery photo i see also one set of terminal cables going to your inverter. So one terminal red + cable and one terminal black - cable. These cables are designed for 100A current, with 5 batteries you have a maximum working current of 125A. So my advice is to install a extra set of cables to your inverter, easy to install in the spare places you have on your batteries.

I think you should change the emplacement of the cable to the axpert king. On your pylontech master battery communication cable is in port B/RS485 on your photo, but this should be the A/CAN port. Although axpert king works with RS485, the pylontech manual says to use A/CAN to communicate in RS485 mode. Confusing for sure! Hope this helps!

Woud it be possible to use the dry contacts to change automaticaly between output inverters and utility when battery is low? When battery is low dry contact will trigger nc relais to cut current output and this triggers automatic dual power control switch to go to utility.