I finally found some pretty charts to help visualize the demand curve during the day.
Here is one from California from today:
The temperature range in Los Angeles today was 66F – 88F and San Jose was 61F – 95F ( peaked at 3pm )
I found it on this webpage which is from the California power consortium. There is plenty of historical data here as well that I will try to dig into soon.
I also found this data from Ontario Canada. The demand curve is significantly different shape, probably because of a different mix between AC and lighting.
It was a mild day today in Ontario, temperatures from 9C – 20C. ( 48F – 68F )
So my chart that I made yesterday was a little off. The peak consumption in California is at 4PM and there is a long tail with continuing high demand late into the evening. The difference between the 2 charts seems to strongly indicate that the AC load of a hot day pushes the peak higher centered around 3-4PM, otherwise it is flatter throughout the work hours. Hopefully I can find some historical data for a really hot day from both places.
It looks like in California there is a lot of surplus power in the morning all the way up til the early afternoon. If you need to charge your car after driving to work, you’ll want to do it in the morning between 7AM and 2PM or so, and not in the late afternoon. Optimal charge time overnight looks like between 1AM and 6AM, but any time from about 10PM til 7AM seems fine.