Hoymiles Inverter Firmware Update Function / HM HMS HMT Updater

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Update your HM / HMS / HMT inverter firmware.
Can be used as an alternative to the original Hoymiles DTU for updating inverter firmware.
The Hoymiles DTU/Cloud itself is neither involved nor required.
Supported models: Hoymiles HM/S/T‑300, 350, 400, 600, 700, 800, 1000, 1200, 1500, 1600, 1800, 2000, 2250.
If the update aborts or the inverter becomes unresponsive after flashing, perform a reflash.
Firmware files are located in: ./Firmware
Update 30_8_26 (HM_1T/2T US)
Firmware_30_8_26.zip

Handle with care and on your own risk!
PSRAM is now optional!
It is recommended to disable all NRF24/Inverter traffic during the update.

implemented PSRAM alternative 02.09.2026:
FirmwareUpdater_openDTU_factory_2026-09-04_13-23.zip
FirmwareUpdater_openDTU_firmware_2026-09-04_13-23.zip

Contained Fimware files:
HM 1T/2T/4T
HMS 1T/2T/4T
HME 4T
HMT 4T/6T

|  ?  | Phase | Type | DSP | ? | ? |MI/B| Version (hex/dec)| CRC |**Serial**|   Info              |
|-----|-------|------|------|---|--|----|------------------|------|----------|-------------------|
HM:
| 0   | 1     | 0    | 0   | 0 | 0 | 0   | 2721 / 1.0.17   | 81  | **1121** | HM 1T MI |
| 0   | 1     | 0    | 0   | 0 | 0 | 0   | 2774 / 1.1.0    | 2E  | **1121** | HM 1T MI |

| 0   | 1     | 1    | 0   | 0 | 0 | 0   | 2720 / 1.0.16   | 81  | **1141** | HM 2T MI |
| 0   | 1     | 1    | 0   | 0 | 0 | 0   | 2776 / 1.1.2    | 2B  | **1141** | HM 2T MI |

| 0   | 1     | 2    | 0   | 0 | 0 | 0   | 2722 / 1.0.18   | 7E  | **1161** | HM 4T MI |
| 0   | 1     | 2    | 0   | 0 | 0 | 0   | 2777 / 1.1.3    | 29  | **1161** | HM 4T MI |

HMS:
| 0   | 1     | 0    | 0   | 0 | 0 | 0   | 4E22 / 2.0.2     | 59  | **1124** | HMS 1T MI (HM-Board) |
| 0   | 1     | 0    | 0   | 0 | 0 | 1   | 4E20 / 2.0.0     | 5A  | **1125/1400/1403** | HMS 1T B |
| 0   | 1     | 0    | 0   | 0 | 0 | 2   | 2774 / 1.1.0     | 2C  | **1126** | HMS 1T US |

| 0   | 1     | 1    | 1   | 0 | 0 | 1   | 2718 / 1.0.8     | 78  | **1143/1144/1144/1410/1412** | HMS 2T / HMS_W_2T |
| 0   | 1     | 1    | 1   | 0 | 0 | 1   | 2845 / 1.3.9     | 4A  | **1143/1144/1144/1410/1412** | HMS 2T / HMS_W_2T |
| 0   | 1     | 1    | 1   | 0 | 0 | 2   | 2778 / 1.1.4     | 17  | **1146** | HMS 2T US |

| 0   | 1     | 2    | 1   | 0 | 0 | 0   | 272B / 1.0.27   | 65  | **1164** | HMS 4T |
| 0   | 1     | 2    | 1   | 0 | 0 | 0   | 2780 / 1.1.12   | 10  | **1164** | HMS 4T |
| 0   | 1     | 2    | 1   | 0 | 0 | 0   | 2786 / 1.1.18   | 0A  | **1164** | HMS 4T Thailand|
| 0   | 1     | 2    | 1   | 0 | 0 | 0   | 4E24 / 2.0.4    | 45  | **1164** | HMS 4T |

| 0   | 4     | 2    | 0   | 0 | 0 | 0   | 2719 / 1.0.9     | 57  | **1162** | HME1 4T MI|
| 0   | 1     | 2    | 2   | 0 | 0 | 0   | 2719 / 1.0.9     | 67  | **1165** | HMS 4T 2000B_T |
| 0   | 1     | 2    | 1   | 1 | 0 | 1   | 4E25 / 2.0.5     | 42  | **1166/1421** | HMS 4T 2000C_B |
| 0   | 1     | 2    | 3   | 0 | 0 | 1   | 283D / 1.3.1     | 31  | **1620** | HMS 4T WB_B  |

HMT:
| 0   | 3     | 5    | 0   | 0 | 0 | 0   | 2779 / 1.1.5     | 04  | **1361** | HMT 4T |
| 0   | 3     | 6    | 0   | 0 | 0 | 0   | 2716 / 1.0.6     | 66  | **1362** | HMT 4T NA R |

| 0   | 3     | 3    | 0   | 0 | 0 | 0   | 27F3 / 1.2.27    | 8C  | **1382** | HMT 6T |

MIT:
| 2   | 1     | 6    | 0   | 0 | 0 | 0   | 28A0 / 1.0.4     | F9  | **1520** | MIT-5000 (?F280034) |

~~If your inverter serial is blocked or not authorized, feel free to contact me.~~

Second option, the almost official way:
Update Inverters by Hoymiles Cloud with official DTU ("Official DTU", "Hoymiles Cloud Account" and ".NET 8 Desktop Runtime" is needed)

Code Repo

Feel free to join the Discord for updates and discussions, etc.

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It is recommended to disable all NRF24/Inverter traffic during the update.
Upload file:

Start Update:

[stefan123t]

Added a reference for the original Feature Request: #1421

Maybe the Code Changes from @dumpfheimer for Updating the Grid Profile should be aligned with this branch for Updating the Firmware Image.

• Set Grid Profile master...dumpfheimer:OpenDTU:dumpfheimer/set-grid-profile
• Firmware Update master...xX-nichtlachen-Xx:OpenDTU:refs/heads/FirmwareUpdate_HM_IV

I assume you both did a thorough test of your respective implementations, but it would make sense to use the same code, as the commands are very similar:
See also Wie wird das DOWN_PRO (0x0E) / DOWN_DAT (0x0A) verwendet
https://github.com/lumapu/ahoy/wiki/Protocol#wie-wird-das-down_pro-0x0e--down_dat-0x0a-verwendet

I think there is also a command to Download a Trace of several of the Waveforms from the Inverter.
Maybe that is something you can use to compare for analysing / adjusting the fit of the generated Sinus wave to the measured values.

[xX-nichtlachen-Xx]

I have a full Grid Profile Update/Edit solution, too.
#3169

[vifino]

Hi. I tried this on my HM-1500-4T which runs 1.0.16 - but I can't get my opendtu fusion v2 to register the 4in1.hex upload. I updated from my old install of OpenDTU.

The POST /api/file/upload?file=firmware/4in1.hex&restart=false gets 200 OK.
But when POST /api/devinfo/update gets trigged from the Start Update button, the console shows response {"message":"Firmware image is not available for this inverter type!","code":1007}.

What am I doing wrong?

[xX-nichtlachen-Xx]

Try the upload in ui. Have a look at the pictures on top.

[vifino]

That's what I did. I uploaded the HM_4T_1_1_3.hex as the 4-in-1 firmware.
That's how I got those POST requests shown in the Firefox debug tools.

[xX-nichtlachen-Xx]

Can you have a look at how much storage on your PSRAM is being used after the upload, expected are about 300kb usage.
The Upload has a Bug it always shows upload passed, even if no file was stored on device, i will fix this.
-> fixed

[mikevd97]

Thanks. It works perfectly with the HMS-800. Is support for the HMS-1600 also planned?

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Already supported, see the updated files at the top of this page.

[mikevd97]

Thanks. After the latest commits, it works on my HMS-1600, too. However, after one failed update, I had to modify the update logic:

Retry after a failed update is impossible: isFirmwareUpdateSupported() requires DevInfo, but DevInfo is only requested after Statistics arrives (Hoymiles.cpp) — and an inverter stuck after a failed update sends neither. Button stays greyed out forever.

Fix: fall back to inv->typeName() when getHwModelName() is empty — it comes from the serial number, needs no radio, parses to the same channel/dsp values. Use it in isFirmwareUpdateSupported(), getFirmwareVariant() and firmwareFileMatchesInverter(). Serial allow-list and .hex identity-row check still apply, so nothing is weakened.

[xX-nichtlachen-Xx]

Oh yeah, I had already been considering that problem/solution as well, but I wanted to implement quick safety firmware file validation first.
Thanks for testing and reporting. <3
-> code is changed

[gitle007]

Just tested it with an HMS1600-4T and an HMS2000-4T. Works great!

The OpenDTU-OnBattery fork strongly recommends using version 1.1.2-4T instead of 2.0.4-4T.

If you have the 1.1.2-4T firmware available, would you mind adding it to the firmware list?

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Succes!

[gitle007]

I successfully downgraded to 1.1.12!

But I had to use an earlier firmware - your latest firmware 2026-08-10_11-39 complained about a hardware mismatch.

Another observation: I had to reboot the openDTU to get the updated inverter firmware version displayed.

Anyway, thank you for implementing this.

[xX-nichtlachen-Xx]

You're welcome! Could you upload your firmware variant, and where did you get it from? Thanks a lot!
And what are the first 4 letters of your inverter’s serial number?

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This was a Bug in the Firmware file Match Check, i am fixing it.
-> fixed and uploaded

[xX-nichtlachen-Xx]

Yeah i knew about the dtu reboot information bug, but never fixed it so far, now it is fixed too.

[rudolfp1979]

has somebody the firmware for 1.11.17 for hms-2000-4t 1164 Hardware-Version 01.10

[xX-nichtlachen-Xx]

1.11.17 or 1.1.17?
May you can try the "HMS_4T_Thailand_1_1_18.hex".

[rudolfp1979]

sorry 1.1.17 what does the thainland mean in it think it is for the wrong country? But i will give it a try tomorrow

[xX-nichtlachen-Xx]

Why dont you want to use "HMS_4T_1_1_12"?

[rudolfp1979]

actually i am trying different firmwares cause of my brand new hms-2000-4t needs the patch for the mit5000 for any reason and i was hoping an other firmware could resolve this too

[tr8-g]

I was able to successfully update the firmware on my two HMT-1800-6T units from 1.0.10 to 1.2.27.
FYI: I used your “generic_esp32s3_psram_N8R2_N16R2” file from yesterday on an openDTU Fusion Board. The update took about half an hour per inverter (it can be a bit nerve-wracking).
Thank you very much!

[Github-Nutzer]

Blöde Frage: Firmwareupdates von Hoymiles-WR die rein von Akkus's gespeist werden schlagen - zumindest auf offiziellem Weg via Hoymiles - Support - fehl. Es ist zwingend ein PV-Paneel anzuschließen. Schätze dass das auch hier der Fall ist?

[xX-nichtlachen-Xx]

Wäre mir so nicht bekannt.
Bei WRs die an nem Netzeil hängen, quasi wie ne Batterie, funktioniert es einwandfrei.
Ich kann mir es nicht so recht vorstellen, warum es an einer Batterie nicht gehen sollte.

[RealNBB]

Ein Inverter hängt bei mir auch direkt am Akku. Update ging ohne Probleme.

Mir erschließt sich auch kein Grund, weshalb das nicht gehen sollte bzw. Probleme bereiten kann.

[dsteinkopf]

"Stupid" question: Why should i upgrade my running inverter? Do we have changelogs? I don't assume the security problem is already solved!?

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If you have an HMS_4T, you can use the tool to switch between these three versions, for example.
But don't feel obligated to do anything.

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The new Security Firmwares are not available yet, as far as I can tell.

[ryan5836600]

Would the HMS_2T_1_0_8.hex or HMS_2T_1_3_9 be applicable to NA models? Here is my device info:
Model: HMS-700-2T-NA
Serial prefix: 1146
Revision family: A02
Firmware: 1.0.1
Bootloader: 0.2.1
Hardware: 01.00
HW part number: 270606598
Production: 2024 week 2

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HMS_2in1_US.zip

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Bu the firmware update for inverter with SN '1146' is not allowed at the moment.

[xX-nichtlachen-Xx]

I added 1146 SN support, you need to reflash the ESP32.

[ryan5836600]

Thank you very much! So this should update my FW from 1.01 to 1.1.4 and that should give me PDL?
Is there a way I can back-up my current 1.01 FW in case it breaks something and I want to revert?
I am worried about flashing because my communication from OpenDTU to inverter is not very reliable, does the inverter handle error checking reasonably well? Would you know more about how I can improve the stability of the A02 inverter communication with OpenDTU, see #3161 (comment)

[xX-nichtlachen-Xx]

Handle with care and on your own risk!
back-up my current 1.01 FW -> with JTAG only
You may have to repeat the update until it succeeds.
1.01 to 1.1.4 and that should give me PDL -> I don't know anything about that (content of firmware).

[RealNBB]

Hello,

you wrote the following above:

It is recommended to disable all NRF24/Inverter traffic during the update.

Does this mean not letting the inverter run under regulation (by OpenDTU-oB) before the upload? Is it better to set it to a fixed wattage?!

I’ll will try it out on three inverters this weekend.

Thanks!

[xX-nichtlachen-Xx]

The new Security Firmwares are not available yet, as far as I can tell.

[kami83]

Thanks a lot for the Answer. Under which categorie i can find the Firmware-Upload function? is it: Settings->Firmware Update? Which FW i should use? My old 1.0.16 or the 1.1.2 from here? Is there a Changelog?

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May have a look at the top of the page.

[kami83]

for me it looks like this. Right?

And is there a Changelog for the Firmware? 1.1.2
BR kami

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Changelogs are not really published by Hoymiles.