brunodu31

Dear all

After studying the service manual, the internal board layout, the Voltronic SOP, and several teardown pictures, we have developed a working hypothesis regarding the intermittent Error 80 observed on some parallel Axpert/Voltronic 5048MG units.
The original Voltronic SOP only addresses LCD flickering by repositioning the MPPT choke wires. However, after a closer analysis of the inverter architecture, we believe the root cause may be broader than the LCD issue.
The MPPT choke is physically mounted far away from the MPPT power board. The two wires connecting the choke to the MPPT board (P2/P3) are relatively long and appear to be part of the MPPT switching current loop. These wires carry high current and high dV/dt switching waveforms generated by the MPPT IGBTs/MOSFETs operating at approximately 50 kHz.
While the toroidal choke itself should radiate very little magnetic field, the long connecting wires form a large switching loop that is likely to generate both conducted and radiated EMI. Inspection of the inverter shows that these wires run very close to several ribbon cables and communication boards, including boards associated with the parallel system (PAR-P board, PAR communication board, communication board and main board).
Our hypothesis is that the switching loop radiates broadband EMI which couples into the nearby ribbon cables and communication circuits. The fundamental switching frequency is only around 50 kHz, but the fast switching edges generate harmonics extending into the MHz range. This may occasionally corrupt communication between the parallel control boards, resulting in Error 80.
To investigate this theory, we will first implement the official Voltronic capacitor modification (2.2 µF film capacitor across PV+ and PV−), which should improve differential-mode filtering on the PV input.
If the problem persists, we plan to shield the two MPPT choke wires. The proposed design is intended to minimize additional capacitance:
each MPPT wire will be routed inside its own PVC insulating tube;
the two tubes will be placed side by side;
a copper braided shield will surround both tubes;
an outer heat-shrink sleeve will provide mechanical protection;
the shield will be connected to chassis earth at one end only;
significant air spacing will remain between the conductors and the shield in order to keep conductor-to-shield capacitance as low as possible (estimated only a few tens of pF).
The objective is not to filter the MPPT current itself, but to contain the radiated electric field generated by the switching loop and prevent coupling into the nearby communication and parallel-control circuitry.
At this stage this remains a hypothesis, but it is consistent with:
the physical layout of the inverter;
the location of the MPPT choke wiring;
the proximity of the communication ribbon cables;
the Voltronic LCD flicker correction;
and the intermittent nature of Error 80.