Mains frequency tracking

Hi folks, I’d love to see the frequency of the mains tracked/charted.

My Tesla solar system with PowerWall+ will change the frequency powering my house if the grid goes out; the grid is 60Hz, but the Tesla PowerWall+ frequency will be different (up to 65Hz, mine is adjusted to 62Hz). This would allow Sense to know when the grid is out and when the house is being powered by other means.

I know I can see the current frequency in Settings, but it isn’t tracked or charted anywhere.

Might be good for people with poor signal quality from their utility provider as well.