GerhardK83

Good evening All I trust that you are all well. I am wondering if it is possible to access the BMS of Greenrich U-P3686 battery via the RS232 connector on the front of the unit so that can see which firmware the batteries are using and I have the following questions: A] What cable is needed to connect to the battery? B] What software is needed to connect to the battery on a Windows OS? C] Does the software display the firmware version? Kind Regards GerhardK83

The AC inputs as well as the AC outputs on the inverters are in parallel and the inverters communicate with each other to share the load between them. https://www.solisinverters.com/uploads/file/Solis_Manual_S6-EH1P(3-8)K-L-PLUS_EUR_V1,3(20260402).pdf P34 in the manual has a nice diagram which illustrates how the inverters are used in parallel. Do you have the label of the 330W solar panels currently in use which indicates the voltage and current of each solar panel?

1) If you are adding a second inverter to the current one then the current inverter must be able to work in parallel with the new inverter so in order for the current inverter to work in parallel it must be the exact same inverter model and the same firmware version and I doubt that the exact same model is still available for purchase. 2) The brand of inverter is dictated by what functions the inverter must perform like feedback to the grid or feedback to non essential loads when there is enough PV power available to power those loads so ask yourself the question would the features that the inverter can provide be utilised or not. 3) The PV power is also dictated by the inverter chosen so first look at the inverters available on the market and then you design your system around that, also remember that there must be enough roof space or space available to mount the solar panels. 4) I would reserve the battery for night time use depending on the loads connected to the inverter. 5) What is the SOC of the battery at 4:00 am, if the SOC is still above 50% then I would increase that time to 5:00 am or 6:00 am or even 7:00 am depending how early the charger kicks in. Also remember that the Pylontech batteries are 0.5C so that means that the battery can only charge or discharge at a rate of half of the current e.g. the UP5000 is 5120 Wh and the voltage is 48V so half of 5120 Wh is 2560 Wh and 2560/48 is 53A so in battery mode the maximum load per battery is half of the total Wh of that battery. I had a quick look at the inverters that The Powerforum Store is selling and there are 2 Solis models which are standing out the Solis S6 Pro 6kW Plus Hybrid Inverter 10 Year Warranty With Display available @ R13843.70 incl vat and the Solis S6 12kW Single Phase Low Voltage Hybrid Inverter (S6-EH1P12K03-NV-YD-L) 10 Year Warranty With Display available @ R34672.50 incl vat Personally I would opt for 2 of the 6Kw units that work in parallel rather than one 12Kw unit and with the money that is saved buy another battery or more solar panels. The Solis 6Kw unit has a Maximum usable PV input power of 9.6Kw and the 12Kw unit has a Maximum usable PV input power of 19.2Kw so there is room for upgrade just remember that the Solis inverters has more than one PV input and the total power quoted above are for all the inputs and the solar panels must be configured accordingly.

Since you are not technical then in order to determine if the earth leakage is on the AC supply to the inverter or AC output of the inverter switch the earth leakage off and if the inverter goes to battery mode then you know that the earth leakage is on the supply side and if the inverter does not go to battery mode then the earth leakage is on the AC output of the inverter. The alternative is to ask the installer or an electrician to come and inspect the installation to determine if the earth leakage is on the AC supply to the inverter or AC output of the inverter and draw a diagram of the system.

Is the earth leakage on the AC supply to the inverter or AC output of the inverter?

@Denns The cross sectional area can be calculated by A = π r^2 or π D^2 / 4 or π * (D / 2)^2

@HennieL The voltage drop is a product of the current flowing through the cable and the resistance of the cable. See the image below, this is the formula to calculate the resistance of a cable. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/resis3.gif

There are four factors which determine the cross sectional area of a cable A] Cable Length B] Cable Resistance C] Operating Temperature D] Current Cable length and the cross sectional area of the cable has an influence on the resistance of the cable. The operating temperature also influences the resistance of the cable and also determines the type of insulation used on the cable. The current that the cable must be able to carry also influences the cable cross sectional area. Silicone cable has a wider operating temperature so a thinner cable can be used for a short distance because the insulation of the cable would be able to handle the heat where PVC would not be able to handle the higher operating temperature and a thicker cable would be used so that the cable would not heat up and burn the insulation off. To determine the cross sectional area of the cables in your photo one must either look at the cable insulation and see if it is not indicated on the insulation or measure one of the strands in the cable, calculate the cross sectional area of the strand measured and then count all the strands in the cable and multiply that by the cross sectional area of the one strand and that would be the total cross sectional area of the cable.

I would not recommend using two different inverters to charge the 4 batteries because A] If you are using comms which inverter would communicate with the batteries because both cannot communicate with the inverters at the same time - it is like working for two bosses one says go there and to that and the other one the exact opposite instruction. B] If voltage settings are used there is also the danger that the batteries can be over charged or that one of the inverters shuts down because the other one is charging the batteries to a too high voltage, LiFePO4 batteries has a very flat voltage curve and on the cheaper inverters using voltage settings is risky - See the attached illustration as an example of the flat voltage vs SOC%. I would recommend that the batteries are split between the inverters. If the 24V batteries looks like the 48V battery with bolt battery terminal connections then do what I did with the Greenrich batteries that I have used in my installation, I used stainless steel grub screws with nuts, washers and lock washers to fasten the lugs to the battery terminal contact and between every lug there is also a washer so looking from the battery terminal it would be lug, washer, lug, washer and between the final washer and nut a lock washer and I used cables linking the batteries to each other instead of cables running from the batteries to bus-bars and from the bus-bars to the inverters. Measure the depth from the battery terminal to see if there are any obstructions inside the battery to make sure that the grub screws do not protrude to deep inside the battery, if memory serves me correct the Greenrich battery has a clearance of about 33mm until an obstruction is met inside the battery so I used 25mm or 30mm long grub screws to fasten all the lugs to the battery terminal connections, your batteries should be more or less the same internal clearance. The lugs of cables which are linking the batteries are rotated 180 deg so that the lugs going to the inverters fits properly without interference.

@AgentMulders if you do not have any 3 phase loads then why don't you downgrade from 3 phase to single phase?

The inverter which you have has a maximum solar power input of 4000W and 500V DC so if your solar panel is 560W and 52.27V Open Circuit then you can have a maximum of 7 solar panels in series before exceeding the 4000W power and with 7 solar panels in series the open circuit voltage is round about 365V so that is below the 500V. High power low voltage single phase inverters are not common because if the power increases and the battery voltage remains the same the current also increases which means thicker cables and more components which can handle the current, e.g. 3000W @ 24V is 125A and 6000W @ 24V is 250A and to safely handle the current then the cable must be at least 35mm2 for the 3Kw and 70mm2 for the 6Kw inverters. If more than one inverter is used in parallel on the same phase then the inverters must be able to communicate with each other because the sine wave output must be in phase otherwise you face other problems with the inverters.

Good evening @Koch903 and welcome to the forum. See my answers below. Regards GerhardK83

Good evening All I trust that you are all well. Since I have not received any feedback regarding the Output Source Priority and Charger Source Priority timers I decided that I will post my findings here. If the timers are set on any of the units the Output Source Priority and Charger Source Priority would change according to the timers and there must be a time difference of one hour between the timers e.g. if the SBU timer is set from 00:00 to 15:00 then the USB timer must be set from 16:00 to 23:00 otherwise the settings does not change. Kind Regards GerhardK83

@Aartappel I would recommend that you contact @Steve87 he has experience with commercial systems of that scale, another option would be @TaliaB.

Good evening All I trust that you are all well. I have 3 of the 7.2Kw Kodak inverters in parallel on a single phase supply and I would like to know if the timers for the Output Source Priority and Charger Source Priority must be set on all 3 the inverters or only the Master inverter? Kind Regards GerhardK83