Sigenergy: add per-string meter

[computeralex92]

Based on no objection on #32715, I tried to implement the support for String seperation in the template for Sigenergy.

Why?

If you have two different roofs (e.g. east / west) connected to the same Sigenergy inverter, the current modbus template is only catching the total power produced by both sides.

Good for many use cases, but if you want to run statistics which roof performed better etc., this is not sufficent and sent you back to the vendor app (didn't check if there an export in the app).

Solution

The template is extended to use the additional modbus registers.
An existing config is just ignoring it, only if you reconfigure the meter to use the new options, they get active.

On my own installation it is working with this setup without any issue for +- a week.

Gotcha

There is one little detail I found out while testing:
As the additional registers are using the DC power from the PV side (so directly voltage × current), the power output mismatch the power from behind the inverter.

Therefore, this new option should only be in use as additional meter for statistics etc., not for the PV overall power meter.
In my setup, this happens:

This mismatch is the power loss by the inverter.
In my opinion a good compromise, as the goal is anyhow to have the statistics in evcc.

Side note

Maybe in a future stage of the GUI, there could be an option to add additional meters to an existing PV meter, as e.g. sub-meter.
Currently the additonal meters are not shown in the GUI.

[sourcery-ai]

Hey - I've reviewed your changes and they look great!

Sourcery assessment

Approved.

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[andig]

@premultiply nice and simple pattern- wdyt?

[premultiply]

Yep, nice pattern. 👍
Just thinking about how it could be further unified for mppts, external inputs external pv meters etc.

[computeralex92]

If other components are also supporting something similar, this would open also the possibility to monitor the PV components itself, the efficiency of the inverter etc.

But just a thought ;-)

[premultiply]

The energy value is missing here for each MPPT.

[computeralex92]

Thanks for the review, but are you able to descibe what is missing here?

The power each MPPT is producing is getting calculated because there is no register produced by Sigenergy to getting the exact power number.

Or did I miss here something?

[computeralex92]

One thing I want to mention and have your opinion on it is this little querk I found:

[site ] DEBUG 2026/08/24 20:12:01 pv 1 power: 0W
[site ] DEBUG 2026/08/24 20:12:01 battery 1 power: 409W
[site ] DEBUG 2026/08/24 20:12:01 ext 2 power: -5W
[site ] DEBUG 2026/08/24 20:12:01 ext 1 power: 12W 

Looks for me like a sensor offset on the current when the PV production is near 0.
In my example, ext 2 is the east side of the roof, so even more in the shadow then the west side.

What do you think, make it sense to filter something like this and set the minimum current value to 0 to avoid this behavior?