This chart is a few years old, but it shows that the peak demand was in the early evening:
https://www.eia.gov/todayinenergy/detail.php?id=830
The peak demand will also vary at different locations and times of year. As the wikipedia article states:
>...It depends on the demography, the economy, the weather, the climate, the season, the day of the week and other factors. For example, in industrialised regions of China or Germany, the peak demands mostly occur in day time, while solar photovoltaic system can help reduce it. However, in more service based economy such as Australia, the daily peak demands often occur in the late afternoon to early evening time (e.g. 4pm to 8pm).
My chart, if you look closely, has a granularity of one half hour. If you want something even more granular, ISO New England data more clearly shows the peak to be between 2pm-3pm for a typical summer month: https://i.imgur.com/rX1JqoJ.png
I think you might have posted the wrong image to imgur. You linked to: https://imgur.com/wTIt5tg
I am not sure how you are getting half hour indications on that weekly chart.
>...ISO New England data more clearly shows the peak to be between 2pm-3pm for a typical summer month:
Yes, that was why wikipedia says:
>...It depends on the demography, the economy, the weather, the climate, the season, the day of the week and other factors. For example, in industrialised regions of China or Germany, the peak demands mostly occur in day time, while solar photovoltaic system can help reduce it. However, in more service based economy such as Australia, the daily peak demands often occur in the late afternoon to early evening time (e.g. 4pm to 8pm).
https://en.wikipedia.org/wiki/Peak_demand
The EIA web site was talking about October, not the summer months when air conditioning would be used.
As another data point, With PG&E pricing, the most expensive hours are noon to six:
https://www.pge.com/en_US/business/rate-plans/rate-plans/tim...
I think my point is that statements like "hat matters is peak grid usage (ie. residential+industrial) and it is actually mid-day—perfect for solar." can over simplify the problem. The amount of demand will vary in different areas at different times of the year and even when it is raining, there will still be demand.
See https://i.myimg.io/wi9J.png
«The EIA web site was talking about October»
This is why I also showed an October chart, with a peak at 3-4pm.
But, yes, peak can vary with weather, time of year, etc. All I'm saying is that in general—not always—peak PV generation coincide reasonably with peak electricity demand.
OK, for many reasons we are just going to have to agree to disagree on that chart. (I just measured https://imgur.com/wTIt5tg and on my machine it definitely is more than 41 pixels between each day but that doesn't mean each pixel is representing exactly x minutes of time, there is no indication on the chart each pixel actually represents 35 minutes or if it is interpolated data, etc. To me it gives a rough showing of energy demand over a week.)
>...This is why I also showed an October chart, with a peak at 3-4pm.
It isn't clear to me why there would be peak demand at 3-4 in the afternoon in an October day. As the EIA site says:
>...During this period, usually in the early evening, operators need more generating capacity–including more costly "peaking" units. Both day-ahead and long-term forecasts account for these peaks to ensure the assignment of adequate capacity.
>...But, yes, peak can vary with weather, time of year, etc. All I'm saying is that in general—not always—peak PV generation coincide reasonably with peak electricity demand.
I think we basically agree on that. Peak PV generation is probably closer to noon, but in general more energy is needed during daylight hours than at night. (And obviously a hot sunny day will spike energy usage for cooling and solar PV is a perfect fit at that time.) The problem to me is when people over simplify this issue. The amount of demand will vary in different areas at different times of the year and even when it is raining, there will still be demand. I've always been a supporter of solar power but there is a lot of handwaving going on when people say we can get 100% of our power from solar and wind without there being some huge advances in energy storage.
If you think of it as two power grids, then "the big power grid"—the industrial grid—can be fully powered by solar, and the residential grid, i.e. "the small power grid", is kind of trivial to solve in comparison.
Even for domestic users, electric storage heaters, water heaters and electric car charging are all amenable to demand shifting. Over time, those will probably become the largest users of electricity if prices keep plunging.
I think there's a lot of money to be made out demand shifting tech, especially if people keep erroneously believing that variability is a problem best solved with expensive lithium ion batteries.
Solar is great for businesses and schools, well basically anything that operates mainly or totally during the day.