Huawei SUN2000: add curtail

[CiNcH83]

a.k.a. zero feed-in / § 9 EEG

Huawei API

Active power control register definition

Testing

(curtailed to 30% of the maximum inverter power)

Open Questions

• Why not pass through the limited power value received from the FNN controlbox and write it to register 47416 (Maximum Feed Grid Power (kW))?

TODOs

• Set Active power control mode via Modbus (7c8034f)
• Template function to distinguish between curtail(true|false) Plugins: add ifelse plugin #29988
• CLI test:
  evcc meter sun2000 --curtail 1
evcc meter sun2000 --curtail 0
• Add capability (Waiting for Add dim/curtail features #29905)

[sourcery-ai]

Hey - I've left some high level feedback:

• In curtailMeter.Curtailed, you return val < m.nominalLimit even when curtailedG returns an error; consider short‑circuiting and returning false, err on error to avoid exposing a potentially misleading curtailed state when the underlying read failed.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- In `curtailMeter.Curtailed`, you return `val < m.nominalLimit` even when `curtailedG` returns an error; consider short‑circuiting and returning `false, err` on error to avoid exposing a potentially misleading curtailed state when the underlying read failed.

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}

[TW2A]

Any updates on this?

[CiNcH83]

Currently on hold until the topic receives more love...

[andig]

Never saw this PR. Whats missing?

[andig]

Ah I see. ATM we only have static curtailment limit, i.e. curtail to 0. There are no urgent plans to change this.

@premultiply do we need to change that?

[CiNcH83]

See initial posting. Curtailment via templating hasn‘t yet been merged.

[andig]

Yeah- that's because that PR is not scoped.

[andig]

Curtailment has been merged

[CiNcH83]

OK. Will check today.

[CiNcH83]

Done.

There are still open questions from my side though, see initial posting.

[andig]

It would also be possible to set the Active power control mode programmatically via register 47415, see #19715 (comment). But it is kind of redundant to do it on every call!?

Whats the question?

Why not pass through the limited power value received from the FNN controlbox and write it to register 47416 (Maximum Feed Grid Power (kW))?

Because the current API doesn't allow that.

Does maxacpower have to become mandatory? It is required to calculate percentage from received limited power.

What received limited power?

[CiNcH83]

Whats the question?

Shall I set the mode as well?

Register: 47415
Description: Active power control mode
Unit: N/A
Gain: 1
Data type: UINT16
Access: RW
Scope: 0: Unlimited (default); 1: DI active scheduling; 5: Zero power grid connection; 6: Power-limited grid connection (kW); 7: Power-limited grid connection (%)

Mode 7 can either be set via Huawei FusionSolar portal (UI, see screenhot initial post) or via Modbus. It is more of a static configuration setting IMHO which is why I don't set it via template (Modbus) but instead added a note to the docu.

What received limited power?

It may not be necessary at the moment because only 0 and 100% is supported. But what if we want to set something in between? We'll need the wattage passed via FNN controlbox to be converted to % of the maximum inverter power, no?

[CiNcH83]

I updated and cleaned up the branch. I am still getting the error:

[main  ] FATAL 2026/05/18 12:41:11 meter [sun2000] cannot create meter 'sun2000': cannot create meter type 'template:huawei-sun2000': cannot create meter type 'custom': curtail: strconv.ParseBool: parsing "7": invalid syntax

So do I need the type stuff? I backed the changes up here so we can still cherrypick what is needed...

[CiNcH83]

  curtailed:
    source: modbus
    {{- include "modbus" . | indent 2 }}
    register:
      address: 47415 # Active power control mode (0=no curtailment, 1=external DI scheduling, 5=zero feed-in, 6=curtail kW, 7=curtail %)
      type: holding
      decode: uint16

Do we need a int2bool for that? Or does this happen implicitly (0=no curtailment/curtailed=false, everything else equates to curtailed=true)? Or is it better to only check for 0 and 7 which is what the template sets?

[CiNcH83]

OK. Looks to be working:

I set it to 30%. So scaling works. Also curtailed works properly:

[sourcery-ai]

Hey - I've left some high level feedback:

• The new BoolSetter handling for constPlugin with typ == "int" always calls set(0), which both ignores the incoming boolean value and overwrites the configured integer, so it likely won’t apply the intended curtailment percentage; consider either mapping true/false to meaningful integer values or using a different mechanism that preserves the configured Value.
• curtailpercent defaults to 0 and is directly written (scaled) to register 47418, which effectively enforces 0% feed-in when curtailment is enabled; if that’s not intended, consider using a sentinel (e.g. unset/nil) or explicit validation to distinguish “no curtailment configured” from “explicit 0% feed-in”.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The new `BoolSetter` handling for `constPlugin` with `typ == "int"` always calls `set(0)`, which both ignores the incoming boolean value and overwrites the configured integer, so it likely won’t apply the intended curtailment percentage; consider either mapping `true/false` to meaningful integer values or using a different mechanism that preserves the configured `Value`.
- `curtailpercent` defaults to `0` and is directly written (scaled) to register `47418`, which effectively enforces 0% feed-in when curtailment is enabled; if that’s not intended, consider using a sentinel (e.g. unset/nil) or explicit validation to distinguish “no curtailment configured” from “explicit 0% feed-in”.

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}

[CiNcH83]

It is probably important for evcc not to perform a curtail(false) if there has not been a curtail(true) before, so only if the system has either been manually curtailed (evcc CLI) or via FNN controlbox. Otherwise evcc will wipe static 60/70% curtailment configurations...

[andig]

the const changes need be reverted, was a bad idea

[CiNcH83]

The template does not work with the reverted const changes!

[main  ] FATAL 2026/05/19 18:38:46 meter [sun2000] cannot create meter 'sun2000': cannot create meter type 'template:huawei-sun2000': cannot create meter type 'custom': curtail: strconv.ParseBool: parsing "7": invalid syntax

[andig]

As commented on the other pr: use convert to switch to int setter.

[CiNcH83]

Can't figure this out. Could use some more help.

[andig]

You need convert with bool2int, same as the other PR