Register 206 = Zero Export Power (target) on Deye SUN-5K-SG03LP1-EU

[gonmag8]

The reason I went looking for this is that I realized that sometimes my inverter zero export control goes very noisy and is oscillating +/-200w around zero (instead of staying stable at the 20W recommended by the manual).
On investigating this issue I have noticed that when this behaviour happens if I set Zero Export Power (target) to 100w wait 30 seconds and then set it back to 20w the controller stabilizes and is then happy at 20w.

Model: Turbo Energy (Deye rebrand) SUN-5K-SG03LP1-EU, single-phase hybrid, firmware confirmed on the SG03LP1 register set (matches single_phase.py / deye_sg03lp1 metric group).

Finding: Holding register 206 is the "Zero Export Power" setpoint shown on the inverter's own LCD menu — separate from register 245 (Max Sell Power). Neither single_phase.py nor kbialek/deye-inverter-mqtt's SG03LP1 docs currently list a register for this setting.

How it was found: Since it wasn't in the published maps, I polled a block of unused/undocumented holding registers (200–249, holding, U_WORD) with ESPHome's modbus_controller while changing "Zero Export Power" on the LCD to three different test values. Register 206 tracked all three changes exactly (raw value = watts, no scaling).

Register details:

Address: 206
Type: holding, U_WORD (unsigned — LCD does not allow negative values)
Range on this unit: 0–500 (min/max as shown on LCD; may vary by firmware/model size)
Scale: 1 (raw register value = Watts, no multiplier)
Write quirk: like most write registers on this model, it needs function code 0x10 (Write Multiple Registers) — in ESPHome that's use_write_multiple: true. Plain single-register writes (0x06) may be rejected depending on firmware.

ESPHome example:

yaml

• platform: modbus_controller
  use_write_multiple: true
  modbus_controller_id: inverter
  id: inverter_esphome_zero_export_power_target
  name: "Zero Export Power Target"
  address: 206
  unit_of_measurement: W
  value_type: U_WORD
  min_value: 0
  max_value: 500
  step: 1

Thank you all for your work :)

[kellerza]

Point your AI agent at the docs and it should be able to build a custom sensor for you

If this works we can add it to the library

[gonmag8]

yes, the HA sensor is now working and I have been using it , sorry if that was not clear.

The post was to see if this could help someone else, I do not need help. Having said that I only got to this solution reading this and other discussions here, so I am thankful for all the info shared here.

The trick does stabilize the controller but seems to be way more effective after sunset (see data below)
I am now building an automation in HA to do this for me :)

I can share some data if anyone is interested ?

In the chart above you can see that the first attempt failed to stabilize the controller as there was still some PV power but when PV power became lower setting the Zero Export Power (target) to 100w wait 30 seconds and then set it back to 20w did stabilize it

[kellerza]

This is really interesting!! So the change allows it to got from 200W fluctuations to less than 20W, or maybe even 10W?

I had a look at mine and seems to also have some fluctuations until I get a big load that draw from the grid, then it also stabalised to ~29W

[gonmag8]

Yes, drawing from the grid would probably have the same effect the problem in my case is that I spend about 10 months without drawing from the grid, I mainly use grid to sell electricity.

One of the AI's have told me ( unsure if true) that this controller bug has been identified and corrected by Deye in the latest firmwares.