ECU-C PowerLimit explanation and APSystems config future

[dcaplopu]

Hi.

First of all, thank you for this useful integration.

I have an ECU-C configured to export 3.0Kw max to the network. I set that setting when we could change the value in the ECU-C webpage.

Now, in the integration, the slider Power Limit for me has values from 0 to 3. If I am not wrong, that slider is the export value from the ECU-C webpage? I have checked that if I configure the value to 0 then the behaviour is like a Zero Export.

My question is, how can we change that value right now to another greater value?

Another thing I have notice is that if the user does not touch the value in the integration, nothing is send to the ECU-C, but when touched for the first time then the integration always sends the selected value. Seems obvious but maybe it is useful to be able to set in the integration that we can not want to send the value to the ECU-C and leave it as the default value for the ECU-C.

About the changes in the ECU-C webpage, Is a shame that a lot of options has been disappeared from the webpage and the EMA App can not offer all that settings. Which is the future of the ECU-C if we can not change anything?

[HAEdwin]

The range of 0 to 3 seems unlikely to me; it should always be 20 to 500. This is hardcoded:

self._attr_native_min_value = 20
self._attr_native_max_value = 500

and applies per channel of the microinverter. Can you show a screenshot where it displays 0 to 3?

The partnership with APsystems has been established, and a future-proof solution via Modbus TCP is coming. Until that solution is available, everything will remain in place so that the integration continues to work.

[dcaplopu]

Hi.

I am talking about the ECU Power Limit values, not the microinverters Max Pwr.

ECU

Microinverters

[HAEdwin]

Oops and sorry, my bad. The power of the ECU-C is indeed limited to between 0 and 3 kW. I think I took the example value from the page but there doesn't seem to be an upper limit.

I would like to suggest that you look for the line:

self._attr_native_max_value = 3

in number.py and change the 3 to a value for your requirement (value is always kW).

After this, you need to restart HA, and you should then be able to adjust the value to the max value you specified. I would like to hear if it works for you.

Indeed the integration does not read the actual value at startup. It is probably possible and certainly useful, but given the developments from migrating to modbus TCP, I will leave it at this for now, as it is just a presentation matter. If needed the setting can always be set using an automation. Hope this answers your questions? Please let me know if you have.

[dcaplopu]

Thank you @HAEdwin

I can not change that value upper to 3 because it is my company allowed max exportation. I was guessing that you were be able to read from the ECU. A coincidence :)

I can confirm you that this value affects to the exportation energy. I have set to 2,5 and the exportation is never upper this value.

Yes. I agree with you that the efforts must be to the new TCP modbus system.

For now, your integration is perfect.

Regards.

[JeffRenard]

Adding a data point on this issue with a clean, reproducible test.

Setup: ECU-C, ID 21500006xxxx, firmware ECU-C-Z_C1.2.26, integration v2.15.0, HA Core 2026.x.

Test performed (2026-09-11, 10:34 local):

Called number.set_value on number.roof_ecu_21500006xxx_power_limit → 0.07 kW manually.
Logs confirm the request reached the ECU and was accepted:
10:34:08.956 DEBUG [custom_components.apsystems_ecu_reader.gui_helpers] Response from ECU on bridging zero export to state open: Set Switch successfully
10:34:15.640 DEBUG [custom_components.apsystems_ecu_reader.gui_helpers] Response from ECU on bridging zero export to state open: Set Switch successfully
Confirmed independently on the ECU's own local page http:///index.php/meter/meter_func1: the power limit value shown there updated to 0.07 kW / 70W.
sensor.roof_ecu_21500006xxxx_current_power before: 330W (5 inverters online, normal daytime production). After the accepted 70W limit (checked several minutes later): still 330W — no curtailment occurred.
Same result the day before during an actual real-world export-limiting need (target 60-70W): HA/local write accepted, grid export stayed strongly negative (~ -1500W). The limitation only actually took effect once I set the same power limit manually through the EMA App (cloud) instead of the local integration/webpage.

Conclusion: the write path (local webinterface set_meter_display_funcs / zero export switch) is accepted by the ECU-C and reflected in its own local UI, but no longer triggers real inverter curtailment. The EMA App (cloud) still works and produces a real effect. This matches what's described above about APsystems phasing out webinterface functionality in favor of a future Modbus TCP control path — it seems the display/storage of the setting still works locally, but the actual enforcement logic has already been decoupled from it on the ECU-C side.

Also noticed, possibly related: grid_ct_a/b/c and production_ct_a/b/c sensors consistently return None in HA, with debug logs showing:

Parsed data: {'power1': [], 'power2': [], 'today_energy': '0', 'subtitle': 'No Data'}

even though the CT data displays correctly on the ECU-C's own meter_display page (live values, moving graphs). Might be an unrelated scraping/HTML-structure issue on that specific page, but flagging it in case it's connected to the same webinterface changes.

Happy to provide more logs/timings if useful for the Modbus TCP work.