Imagine, if you wil, a Guage that has a needle that points straight up, with a value of 0. To the left, you have negative voltage up to -5. To the right, positive voltage, also up to 5. The neutral position of this gauage is zero. Any deviation from 0, will be either a positive or negative number.
How do Imake a gauge in Grafana perform in this manner. The guges here all seem to start on the left side, and start at zero.