5 Kw MPPT Shutdown
I have a 5Kw Sunsynk installed for more than a year. 2x10x250w PV array. FreedomWon 8/10 Battery. Up to now it has operated as expected. Yet today the MPPT tracker appear to have shutdown. No fault conditions or alarms are reported. Green light on (DC AC and NORMAL) PV string measured 320 V shown on inverter (and measured on strings) but no power generated on one string and only 40W on the other. If I switch on and off the inverter the behavior remains. When I totally switch off (Disconnect all power ac & dc) the tracker started to work after switch on for a minute or 2 and then revert to this behavior. After around 20-30 minutes it returned to normal operation. Do I have a faulty inverter or is there something else to investigate.
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After some investigation over the past two days it is tied to the 100%SOC of the battery ( FreedomWon 8/10 connected via CAN protocol 0). The moment the battery reaches 100% charge the MPPT will shutdown for some time 20-30min even though there is still load (UPS) port and a load on the GRID port. If the battery is disconnected the MPPT's will immediately resume tracking and supplying power.
Further investigation also shown that this was not the first occurrence but has been happening ever since the battery was set to supply power according to the schedule. Will drain the battery to 80% from 5:50 AM. After 12:30 the battery is set to 100% to ensure it is fully charged before sunset. Grid charge is set for after sunset 16:40. Priority Load is set and no power is exported. (100W drawn)
Lowering the battery drain to a value 75% in order to not have a SOC of 100% before sunset - last bit charged from the GRID - removes the behavior.
The reason for this is to ensure a fully charged battery for possible evening power interruptions and only to drain the battery as much as can be replenish before sunset.