TL;DR
On a three-unit Solakon ONE multiphase system, the in-app energy plans are locked (“energy plans can only be created in single-device mode”). I tried to reach the same goal — charging the batteries from the grid during cheap Tibber hours — over Modbus TCP instead. Activating remote control on a single unit takes that unit out of the group regulation and makes another unit report error 7181 “AC Parallel-Alarm”. Clearing the register restores normal operation. Solakon support could not confirm whether Modbus remote control is meant to work at all in multiphase mode. Posting the full write-up in case others hit the same wall, and to ask whether anyone has found a working approach.
Setup
- 3× Solakon ONE in a multiphase group (ONE 6.33 kWh with PV strings, TWO and THREE 2.11 kWh, AC-only, no PV)
- Home Assistant OS 2026.6.x
- HACS integration
solakon-de/solakon-one-homeassistant - Dynamic tariff via Tibber + Tibber Pulse
- Shelly Pro 3EM as the grid meter
- Modbus TCP, port 502, 30 s poll interval
What I wanted
Charge all three batteries to ~80% during the cheap window (Tibber is typically cheapest here 13:00–16:00), then use that energy in the expensive evening hours.
Why the obvious path is blocked
In multiphase mode the app shows: “The device is in a multiphase system and regulates feed-in and charging automatically. Energy plans can only be created in single-device mode.” So the built-in scheduling is unavailable by design as soon as the group is active.
The established community blueprint for this (D4nte85’s Nulleinspeisung/AC-charge blueprint) relies on setting a 0 W 24h energy plan as the base state — which is exactly what multiphase mode forbids. So that route is closed too.
What happened over Modbus
I activated remote control on THREE only:
- register 46001 = 3 (bit0 = remote on, bit1 = consumption direction, bits3:2 = target AC)
- this is documented in Solakon’s Modbus spec v02/26 as “charge, target AC, PV priority”
Timeline (all times local, one poll interval = ~30 s):
- 18:21:02 — THREE: 46001 set to 3. No power command issued yet (46003 = 0).
- 18:21:34 — ONE collapses: AC output 622 → 268 W, battery power 208 → 0 W. ONE’s battery is fully blocked. THREE is still not moving any power.
- 18:25:xx — I set a power command on THREE; it starts moving power.
- 18:29 — app shows ONE as “restricted”, error code 7181 “AC Parallel-Alarm”.
- 18:30:30 — THREE: 46001 back to 0.
- 18:30:54 — ONE recovers: 534 W, battery 183 W. Normal operation restored.
The key detail: ONE broke 32 seconds after remote control was enabled on THREE — before THREE moved any power at all. The power command came four minutes later. So the trigger is enabling remote control (bit 0 of 46001) on a single group member, not any actual power flow or its direction. ONE’s battery was blocked for about nine minutes while nothing was changed on ONE itself.
Things worth noting
- The Modbus alarm registers (39067–39069) stayed at 0 on all three units the whole time, even while the app showed 7181. The code appears to come from Solakon’s cloud logic, not from the inverter — so a controller driving Modbus has no way to see this state and back off on its own.
- All Modbus writes were acknowledged successfully; readback showed the written values. The device gives no signal that the command is problematic in group operation — it just silently drops out of the group.
- Separate integration bug I found along the way: the “force power” number entity writes the setpoint into the reactive-power register (46005) instead of the active-power register (46003), so force mode engages but no power flows. Filing that upstream separately.
- Also: the README’s sign convention for remote power is inverted. Per the spec, direction is bit 1 of 46001 and the power value is a magnitude. Writing −1200 with 46001 = 3 made the unit discharge, not charge.
Solakon support response (summarised)
They could not confirm that Modbus remote control via 46001/46003 is intended for parallel operation in a multiphase group. They thought it plausible that single-unit activation is exactly what causes the AC-parallel conflict, but could not confirm whether synchronous activation on all units is supported, and had no recommended procedure. They also could not confirm whether the spec’s low-import charging registers (46503 threshold SOC, 46506 ChrInLowImport, 46507–46514 time windows) are supported on the Solakon ONE or effective in multiphase mode — those registers carry a “*” marker they described as “model-dependent or reserved/not yet released”.
My open questions to the community
- Is anyone running a multiphase Solakon ONE group (or a comparable multi-inverter setup) and successfully doing scheduled grid charging on a dynamic tariff? If so, how?
- Has anyone tried synchronous remote-control activation on all group members in the same poll, and does that avoid the AC-parallel conflict?
- Are the spec’s low-import charging registers (46503 / 46506 / 46507–46514) actually usable on the ONE, and do they survive a reboot? These are settings, not remote-control commands, so in theory they might not kick the unit out of the group the way 46001 does — but I haven’t dared test-write them yet on a live group.
For now I’ve disabled all my charge automations and left the group in its default self-regulating mode. Happy to share raw HA history CSV if useful.