Hi, I have an EasySolar-II GX 5kVA (serial: HQ2523KW2Z7, firmware V558) installed 3-4 months ago with a Pylontech U5000 LFP battery, communicating via CAN/DVCC.
Since installation, the unit emits a strong rubber/sulphur smell (similar to vulcanized rubber or ebonite) consistently when AC load exceeds 2-3kW while MPPT is simultaneously active and charging. The smell comes from the rear of the unit with no hot air discharge.
What has been done so far:
Installer checked all connections and wiring — no issues found
Unit was sent to the distributor (Darcom Energy, Romania) for service
Firmware updated to V558
Unit tested at 4000W AC + 2000W MPPT for 1-2 hours — smell not reproduced
Unit returned with a diagnostic fee, defect unresolved
Key detail: Testing was done without the actual Pylontech U5000 and without real installation cabling. The smell is 100% reproducible on-site under real conditions.
My hypothesis: internal transformer/inductor impregnation varnish emitting under combined high electromagnetic load. No thermal alarm, no error codes in VRM.
Has anyone experienced similar? Could this be a known batch issue with transformer varnish? Any advice on how to escalate beyond the distributor loop would be appreciated.
Thank you.