Fallback components in generated formulas in LogicalMeter

[shsms]

What's needed?

Support for automatic logical meter formulas to be regenerated with fallback components from the component graph, if available.

For example, in the grid_power() formula, power values from all components directly attached to the grid component are added. These are usually just meters. But one of these meters fails, and that meter has a fallback component, values from the fallback components can be used in the formula instead.

In the first version, this can be done for just meters attached to inverters. If such meters fail, values from the inverters can be used instead.

This might also be possible with meters attached to ev-chargers, if we can be confident that there are no hidden load behind such meters, and it is just the ev chargers.

This will NOT be possible

• if the main meter fails, whether it is on the grid side or not,
• if a PV meter fails,

because both those don't have fallback devices in the component graph that we can get power readings from.

Proposed solution

No response

Use cases

No response

Alternatives and workarounds

No response

Additional context

No response

[matthias-wende-frequenz]

Additionally the LogicalMeter might raise an alert that it is working in fallback mode and that can be picked up by an app, which can e.g. trigger an UI alert.

[thomas-nicolai-frequenz]

if a PV meter fails,

Well we can read that from the PV inverter which is a component on the component graph.