Strange red horizontal line in graph, source unknown?

I have been using Grafana for about a year, mostly to display “past 12 hours” of voltage/current data on my off-grid solar power system. Recently I notice a static horizontal red line on my graphs, independant of the scale/timeframe, it’s not grabbable and does not show up in the hover-over value display. What could it be? I’ve searched all the settings, metrics, axis etc. screens and can’t find whats causing it.

Can anyone tell me what that is and how to remove it? I’m sure it wasn’t there a few weeks ago.

Have you added an alert rule recently?


Not exactly recently (a few weeks ago) but I suppose it’s possible there is a correlation… but I can’t see any. Here is my alert config.

Well, I’d say that threshold of 48 in your alert corresponds precisely with
the red line value on the left-hand Y axis.

Try temporarily changing the threshold value and see if the line moves.

I don’t know whether there’s any way to have the alert not displayed on the


Oh man. I feel so dumb. You’re absolutely right.
I didn’t see that because the alert threshold concerned a value on the right Y-scale, not the left Y-scale, so it was visually nowhere near the value where it would have made sense.
I should have tried changing it anyway, the line even moves in realtime when editing the threshold field…
So the question still remains: how can I remove it, or at least make it follow the righthand Y scale? The way it is, it makes no sense at all, and I don’t want to move the voltage axis to the left.