Feedthrough and Downstream Lugs sensors report unreliable values from the SPAN API

[cayossarian]

The values are not properly calculated and appear to be raw synthesis of upstream lugs plus downstream values.

See discussion #230

[cayossarian]

The underlying raw Homie MQTT values are incorrect, need to open a downstream issue with SPAN.

[SPAN-API-Client-Docs](spanio/SPAN-API-Client-Docs#13)

[daking13]

After updating to 2.0.7b5, the Feed Through Power sensor improved for the better, but still seeing occassional spikes and negative values, which aren't expected. You can see the before and after here, upgrade was applied around 7:35 in the below timeline. It's still not stable or accurate as it was in 1.x with the v1 API SPAN data

[cayossarian]

Yeah I was worried about that since the panel doesn't emit the the same fidelity as the panel CT which likely gathers data at the same clock frequency when it calculates those sensors. I'm not sure what your scan interval is set to in the integration but if not already at zero and you have the CPU set it to zero to get it a bit smoother but it won't be perfect for the reasons I just mentioned.

Given that SPAN plans to fix this in the summer time frame it's difficult to justify building some Frankenstein v1/v2 beast for this one sensor. I'd recommend disabling the sensor until SPAN provides a fix as I'm likely to go back to the previous "honest" case for the sensor in v2.0.7 in the underlying package so when the defect is fixed we don't need yet another fix to unwind the beta band-aide. Alternatively you can opt to run that beta and, with a template, you can clamp the negative spikes to zero and anything over a upper threshold if you really want the sensor as best effort.

[cayossarian]

Reportedly this issue is fixed in the firmware release-202621

Let us know if what you see is what you'd expect.

[cayossarian]

There is now some doubt that the firmware fixed this defect so I'll leave it open.

[cayossarian]

Please read this before opening a new issue about a Feedthrough or Downstream sensor.

Five sensors report values the SPAN API itself does not produce reliably. The source of every one of these is the API, not the integration: the values are published by the panel and passed through unchanged, and no transformation on our side recovers a correct reading.

The affected entities

• Feedthrough Power
• Feedthrough Produced Energy
• Feedthrough Consumed Energy
• Downstream L1 Current
• Downstream L2 Current

The defects, as documented against the API

1. The feedthrough energy registers are computed from two unrelated counters, so they can decrease or go negative, and on a panel with no feedthrough load they report roughly whole-panel figures where the truth is zero.
2. The feedthrough power reading is inverted relative to every other terminal on the enclosure — positive when power leaves, where everything else is positive inbound. The integration does not negate it to compensate, deliberately: a firmware fix would then arrive as a second inversion.
3. The downstream currents report the upstream service conductors rather than a downstream measurement.

All three predate firmware r202633 and are not introduced by any release of this integration. Upstream tracking: spanio/SPAN-API-Client-Docs#13

What release 2.1.0 does

New installations do not get these five — they are switched off by default from 2.1.0 on.

Existing installations keep them, switched on and reporting. Home Assistant consults the enabled-by-default setting only when an entity is first created, so an upgrade cannot reach back and change what you already have. Nothing is removed, no history is lost and no entity ID moves. If you use any of the five on a dashboard or in an automation, disabling them yourself is worth doing — but that is your decision, not something an upgrade should do to you.

If your readings look wrong

That is expected, and it is this issue. Please comment here rather than opening a new one. A separate report is still welcome for anything outside the five entities listed above.

This stays open until the API publishes values that can be relied on.