Negative knob, zero-based starting point

Hi folks,

I have a knob which goes from -1000 to +6000 and is showing my grid power usage. When the sun is shining and I am feeding back into the grid I go negative.

I want the bar of the knob to start at zero and not at -1000. Does anyone know of a similar knob or how to make this one behave like this?

A similar question was asked here: Knob widget set center point?