Two 3.6KW Eco parallel - Hunting
I have recently had a second 3.6 eco added in parallel, wired as per the manuals and recommendations.
(both inverters connected to the batteries via busbars with dc fused disconnects.. Tried individual AC connections and combined)
The original eco worked perfectly with 20Kw batteries and 4.6Kw of panels on an east west array. When operating on its own there is no hunting. As soon as I add the second inverter (With additional 3.6Kw panels) the hunting starts when in parallel.
If I revert back to a single eco the hunting disappears.
The second eco works fine on its own as a grid tied unit, no batteries. I have swapped out the coms cable between the inverters, using two other yellow cables supplied with the units. I also tried a standard network patch cable - still the same.
Both inverters on same firmware.
Any suggestions on what I am missing?
Traces showing hunting;
This one shows the first eco trace as a single. At 9pm I started the parallel system.
Parallel export, then zero export to CT.
Any help / advice appreciated!!
Good Morning @sdenyer, I installed 2 3.6kW ECCOs in parallel with a Sunsynk CATL 20kW battery bank in January 2023, I had similar issues with the paralleling, asked for assistance on the forums, some good replies but none resolved the problem. I have just completed a full rebuild of the system as single invertors, outside in a purpose built shed, they were getting too hot in my plant room! thought maybe that had something to do with the problem. I have set them up with 2 * banks of 20kW batteries - one bank 4 * Dyness DL5.0C and a bank of 4 * Sunsynk CATL 5.12, one array of 7.2kW full East into 1 inverter and the other Array of 7.2kW full West into the other invertor. I am now achieving over 90kW / Day on full sun days, I never achieved better than 75kW on a full sun day in June as a paralleled pair, so I am more than happy to be achieving circa 15% increase in output by going single inverter. The losses were happening as the sun passed the midday azimuth into the afternoon when the output would drop on the slave, this happened even if I swapped out East West mixed strings, or just swapped them out East West. My opinion - the parallel pair cant cope with the mismatch in input, i.e., the east array in decline and the west input increasing, the mismatch in inputs was too much for the system to balance, I suspect on a South array the pair would work better, as very little imbalance in the inputs.