Difference creation for charts in Grafana

Hello everyone,
I use home assisstant. The PV system is connected to it via solar-log and the bidirectional meter.
Unfortunately, the output of the bidirectional meter is the sum of consumption and PV system.
So I can’t see the current demand.

If I were able to add the PV system data to the bidirectional meter data, I would be able to see the current demand.
Does anyone know how to set this up in Grafana?

Here is a screenshot of what the output looks like now.