Virtual feeds of Virtual Feeds, or Brackets, or Variables, or something?

Hi,

I have a virtual feed which is my grid connection but filtered with “allow negative” which I call “Grid Feed-in”

I also have a CT on my solar, “PV CT”

I’d like a virtual feed of these two that I’d call “Self Consumption” that is “PV CT” - “Grid Feed-in”

This should theoretically be the amount of power I’ve self-consumed.

But I can’t see how to make the logic in feeds work. I cant take a virtual as a source for another virtual and I need to do the “allow negative” on the Grid CT before I use it in the process.

Basically I’m after the mathematical concept of brackets for virtual feeds.

Or the concept of storing the current value in a variable to use again later.

Is that possible?

I know I could store the calculated values from this point forward but Virtual Feeds would let me see this data point historically.

on your grid feed, alfter the last item add “reset original” “allow negitive” “+/-feed” {PV CT} “log to feed”