Solar Forecast & Production - How to make charts?

Hello everyone,

I have a comprehension question, because I can’t figure it out.

My goal is to create a graph that shows the current + already made PV production and the expected forcast.
I would like to have a virtual display of how much PV electricity could still be available today.
I want to use the forecast value to determine whether there would be enough power available for the dishwasher, for example, or to start it automatically during the day.
(Dishwasher is still to come, is still on order, can’t test anything).

I have been connecting my PV system to openHAB for years and log everything.
It works wonderfully.
I have the current production in watts there and can display it as a progression diagram.

I have now seen and installed the Solar Forcast binding.
I’m currently using it in free mode without the ForecastSolar PV API key.
I have also created the individual channels.

However, when I now want to create a diagram, it doesn’t work at all.
I currently have the following problems:

  • I think the values of the API are formatted incorrectly, I think they are all x1000. So not 10 watts but 10000 watts.
  • If I add the current production and forcast to a page as a chart, I get both lines displayed
  • If I set an offset of 1 day to the forcast, only the forecast line is displayed, everything else is missing

How do I make this chart?
Can someone here possibly write me the individual steps?
I don’t understand it and the documentation was unfortunately not very helpful.
There is a video on YouTube in (I think) Italian where a nice gentleman shows how to create the diagrams, but it didn’t work 100% for me.

It would be great if everything could be set up via the web interface and there was no need to experiment with config files.
I read a lot about config files in the documentation.

:slight_smile:

And linked them to Items?

What type of Item? Number or Number:Power? If Number:Power, what is the unit metadata set to? What unit does the Solar Forecast binding provide?

What is your persistence configuration? Does it include forecast as a strategy at least for the Items with values in the future? By default, only past values get saved to persistence and therefore only past values can be charted.

In addition, forecast doesn’t work with rrd4j and mapdb. You must use some other database to store future values (lots of people use MariaDB or InfluxDB).

The chart is only going to be able to show the values that are stored, but the chart is also kind of dumb. It only shows the values that are stored. So if you are not seeing data in the chart, it’s because that data doesn’t exist in persistence.

Persistence can be configured in the UI under Settings → Persistence.

Number:Power is set and the unit is set to W.
The settings are all set to default values, I haven’t adjusted anything.

Ooooooh I have rrd4j as database in use.
Then that’s probably the problem.
Maybe I should think about changing here.

Consider using InMemory as DB for only those items (or any “mirror items”) that you may want to chart.