Using PV pool in locations without PV cause error

[shsms]

What happened?

2024-12-10T09:31:59+0100 ERROR    frequenz.sdk._internal._asyncio:50: Restarting after exception
Traceback (most recent call last):
  File "/frequenz-app-edge/.venv2/lib/python3.11/site-packages/frequenz/sdk/_internal/_asyncio.py", line 48, in run_forever
    await async_callable()
  File "/frequenz-app-edge/.venv2/lib/python3.11/site-packages/frequenz/sdk/timeseries/pv_pool/_system_bounds_tracker.py", line 108, in _run
    pv_data_rx = merge(
                 ^^^^^^
  File "/frequenz-app-edge/.venv2/lib/python3.11/site-packages/frequenz/channels/_merge.py", line 92, in merge
    raise ValueError("At least one receiver must be provided")
ValueError: At least one receiver must be provided

This was from a setup without PV inverters.

What did you expect instead?

It shouldn't crash or cause errors. However, the propose_power method could print a warning when there are no components.

Affected version(s)

No response

Affected part(s)

Data pipeline (part:data-pipeline)

Extra information

No response

[ela-kotulska-frequenz]

Unfortunately it looks like creating pv pool causes this errors.

self._pv_pool = microgrid.new_pv_pool(priority=priority)

It starts other actors and one of them subscribes for system bounds and frequenz/sdk/timeseries/pv_pool/_system_bounds_tracker.py/_system_bounds_tracker. raises error

These actors started when I create pv_pool:

frequenz.sdk.actor._actor:86: Actor PowerDistributingActor[131823700983008]: Started.
frequenz.sdk.actor._actor:86: Actor PowerManagingActor[131823700983680]: Started.
frequenz.sdk.actor._actor:86: Actor DataSourcingActor[131823701247040]: Started.
frequenz.sdk.actor._actor:86: Actor ComponentMetricsResamplingActor[131823701247328]: Started.

[llucax]

However, the propose_power method could print a warning when there are no components.

I think we should just raise an exception if you are creating a PV pool and there are no PVs. I don't see any reason to create a phantom PV pool.

Although when we start refreshing the component graph, this would make sense.

[shsms]

I think we should just raise an exception if you are creating a PV pool and there are no PVs. I don't see any reason to create a phantom PV pool.

People would want to build formulas with pv_pool.power, etc. without having to worry about whether there are PVs at a location. So we should support this.

[llucax]

True. Tricky, because in that case having a warning would be annoying and spammy, because it might be a perfectly normal situation that is emitting spurious warnings. I guess we'll have to rely on a good monitoring system that allow us to filter out those warnings in locations where the warning is expected.