When does electricity demand peak?

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I frequently hear claims that Germany and other European countries have a peak in electricity demand in the middle of the day, and that solar power can cover this peak. Where this belief comes from I do not know. Certainly, it is true for large parts of America, where electricity demand peaks in the middle of the day in summer when Americans are using their air conditions to excess. Not so in most of Europe where the demand is not in summer, or winter, but on cold winter nights.

To check this I pulled some data together for European countries from the website of PF Bach. Hourly load data for Germany, Britain, Ireland, France, Belgium and Denmark are available. They all show a clear peak at night.

I will show this with two straightforward graphs. The first shows maximum hourly load at each hour of the day throughout the year. To make things clearer I have scaled the graph so that 1 is the maximum for each country.  In other words the hour in the graph with a peak of 1 is when the actual peak occurs.

You can see that all of the peaks occur between 6 and 9 pm in all 6 countries.


What about monthly maximums? Below I’ve plotted the maximum hourly output in each month of the year. As is clear the peak demand occurs in January or December in every country. And the summer peak is much, much lower than the summer peak everywhere.


So, these countries all have demand peaks on Winter nights. This is not likely to change either. Electrification of heating will inevitably make the seasonal peak in heating even more pronounced. An obvious consequence is that solar power cannot replace any fossil fuel capacity in these countries, because of its in ability to produce energy after 5 pm in Winter. That peak will need to be met by something other than solar. This, again, is in contrast to America where solar panels can replace some fossil fuel capacity. Perhaps I will write about this in some more depth in the future.





3 thoughts on “When does electricity demand peak?

    Ruth Dixon said:
    September 29, 2014 at 6:50 pm

    Should the horizontal axis on the final graph be labelled ‘month’?

    It’s interesting that the evening peak, presumably for domestic heating, outweighs the use of electricity for industry or businesses which would likely peak during the working day. And (if I’ve read the legend correctly) that Germany has such a flat monthly profile but France has such a steep one. I wonder if more domestic heating is electric in France.

    I’ve written about my (personal, UK) electricity and gas usage and solar power generation which shows that my family, at least, fits with the bigger picture that you show. http://mygardenpond.wordpress.com/2013/06/30/my-garden-and-solar-panels/


      Robert Wilson said:
      September 29, 2014 at 6:58 pm

      fixed the label problem. The code I used for one graph was copied from the other one, and I forgot to change the label.

      France actually has a lot more electric heating than Germany, which explains part of the difference. I think that 1/3 of heating in France is electric, which is far higher than Germany. Though I’m not sure of the precise numbers for Germany. Heating itself has a far more seasonal load than electricity, so electric heating will clearly have a big impact on seasonality.


        donoughshanahan said:
        October 1, 2014 at 11:44 am

        Not great data but

        As far as your graphs go, I am surprised a bit by the first one which indicates almost full load continuously through the working day until around 20:00. sure it is not at full load but it is above 905 in any cases. Potential implications for charging electric car plans.


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