https://www.caiso.com/Documents/CaliforniaISOPeakLoadHistory...
(Note also in your visualisation that all times are Eastern and should be adjusted for different localities. And if you go to a summer week rather than a winter week, you'll find the true peak, which is much higher, and which has a pretty standard curve with a peak that overlaps sunlight hours.)
They have this summer's data too, though no way to link directly, and it still peaks at ~7pm: https://i.imgur.com/16mssuH.png . Using the 16th as an example, a peak demand of 44,008 megawatthours @ 20H PDT. Comparing that to their generation graphs, which you can separate into sources, like solar. On the 16th, peak solar generation is at 11 @ 13,201 megawatthours. By 6PM, it's down to 853 megawatthours. By peak time, it's nothing. My own residential solar matches that curve on that date.
The United States electric grid data is freely available and pretty neat: https://www.eia.gov/electricity/gridmonitor/dashboard/electr... Choose a grid or a state to get regional time and you can see that region's peak will usually be 4-7pm. You can even see that weekend peaks are a bit lower, and that there's a second peak at ~10am when people get to work.