MPPT tracking bug, possibly started after v1.61 firmware

Hi all,

I’ve been testing multiple Victron MPPTs side‑by‑side and want to share one last clear report for the devs to see.

  • SmartSolar 100/50 & 150/45 (v1.61 v1.64 v1.67 v1.68):

    • On v1.61+ and v1.68, PV voltage drifts upward under inverter load instead of locking to the knee of MPP.

    • Efficiency sits at 94% - 95% most of the time, but it does not track MPP at load

    • Same array, same conditions — only difference is hardware revision + firmware branch.

  • SmartSolar 100/15 (v1.61 v1.64 v1.67 v1.68):

    Appears stable, the MPP tracking and efficiency is great, mostly sits at 97% even when the unit heats up to 50C+.

  • BlueSolar 100/50 rev2 on v1.16: (Still running the unit on firmware version 1.16, so I can see what’s causing the tracking bug)

    • Tracks MPP cleanly, does not go towards the VOC when there is load running on the battery side.

    • Efficiency sits at 93% - 94% most of the time, but at least it locks to the MPP properly.

    • This rules out “bad sensors” as the main issue.

The remaining two possibilities:

  1. Hardware change — later units may have reduced/altered input filtering (caps/snubber), making them more sensitive to inverter ripple.

  2. Firmware regression — post‑1.61, the control loop handling fails to settle on MPP when the load is running.

Evidence:

Since I’ve sold the previous MPPTs, and the latest purchase was the BlueSolar 100 | 50 rev2, which was sitting in the store since 2017, and has 1.16 firmware.

If I update this unit to the latest available firmware v1.68. Will I get the tracking bug like the other two MPPTs? I do not want to take any chances unless I get a backup of a stable firmware.

Hoping for someone from the Victron team to discuss this further.