Graph of the day: German solar power exports

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Here is a rather obvious cycle. Solar power output goes up during the day, and down to zero at night. Remarkably, Germany’s electricity imports and exports now follow an identical cycle. Electricity is exported when the sun comes out and is imported when it goes down. At least during summer. Here is what happened in June this year:


The peak in exports and the peak in solar power is more or less identical. So, when the sun comes up German power prices go down (relative to its neighbours) and it starts exporting power. When it goes down German power prices go up (relatively speaking) and Germany starts importing power again.

You can also see that exports increase significantly when it is very windy on the 2nd June.

This shows just how difficult it is to work with high accuracy how much renewables, or nuclear, reduce emissions. Not only do you need to consider what renewables are displacing within a country, but also what is displaced via exports. And if you want a real mental challenge try estimating how much Danish wind farms reduce emissions. Denmark more or less has two electricity grids, and often imports and exports from and to Sweden and Germany at the same time. And does a MWh from a Danish wind farm that displaces a MWh of Norwegian hydro reduce emissions at all?Energinet


6 thoughts on “Graph of the day: German solar power exports

    Donough Shanahan said:
    July 15, 2013 at 12:03 pm

    Do we know what price the electricity is exported at? Because of a lot of solar electricity is being exported and the FiT is not being covered by the export price, then Germans are subsidising the cost of electricity abroad.


      Robert Wilson said:
      July 16, 2013 at 1:03 pm


      Some people have written about this. The wholesale price is lowered in Germany, so neighbouring countries can buy cheaper electricity. And because the cost of FiT is then added on later in Germany, you could argue that Germany is subsidising cheaper electricity in neighbouring countries. I haven’t seen this analysed in any real depth though. It may not be that important.


        Donough Shanahan said:
        July 17, 2013 at 8:39 am

        I have no analysis to reference either. However I do think it is important. If the wholesale price drops a lot, it then makes sence to sell abroad albeit at a reduce margin as compared to when the wholesale price is ‘normal’ or not excessively low. As the producer I can then reclaim the Fit to make the reduced margin more bearable. However as a German consumer I have paid for excess capacity that I cannot use and now I have to pay a subcharge to cover the cost of the Fit despite the electricity now being used abroad.

        Clearly what the Fit is doing is supporting the generator of electricity but is not creating a balanced grid. It also charges the consumer for a product that they do not see. To do the analysis you would take your graph and try and get an accurate determination for what power is being exported (rather than correlation as I suggest you have here to the basic assumption that excess solar capacity is either exported or displaces something else to be exported seems sound: see Greenpeace below Figure 25 etc) and then break that down as a percentage of exports. you could then try and get a measure in terms of ‘%Fit exported’. It would seem possible to get this breakdown of export data though I have yet to get.


    Thomas Gerke said:
    July 15, 2013 at 4:38 pm

    Very cute Robert. Tell me:

    What is more likly?

    A. Your Tale:
    Solar energy produced on the distribution grid gets transformed several times to be exported over the pan-european pan european transmission grid.

    B. Reality:
    Solar supplies the electricity needs on the distribution grid during daytime and reduces demand from the transmission grid. Since all centralized power stations are hooked to the high voltage transmission grid, the German nuclear and lignite baseload power plants are able to undercut the prices of mid- & peak-load power plants in neighbouring countries => exporting at noon.

    Sure it would be best if other countries had solar too, then lignite power stations would have to shut down at noon, reducing their load hours and making them unprofitable (going offline).


      Robert Wilson said:
      July 15, 2013 at 4:44 pm


      Before criticising my “tale” at least make some effort to understand what it is.

      And your fantasy that Germany will shut down its lignite power plants is rather amusing. Why not just make all fossil fuel plants unprofitable by 2020 and go fossil fuel free?


        Thomas Gerke said:
        July 16, 2013 at 10:13 am

        It’s too early to tell what will happen. Right now we are in a rather intensive political & ecconomic power struggle here in Germany.

        Many communities, regions & state governments want to rapidly expand renewable energy generation, generating on-site solar is now cheaper than the industrial electricity rate and the conventional power sector faces a period of structural change.

        Here’s what we know:
        – Lignite power is currently the cheapest power source in Europe due to the low ETS failure.
        – Renewables will propably keep growing due to (regional) political support & for macro economic reasons.
        – Only RWE & Vattenfall operate lignite power stations in Germany.
        – The market framework will be re-design after the next election

        Since the flood of lignite power on days of high renewable penetration cuts very deep into the revenue of load following power plants (especially gas, but also hard coal) there will propably be no united conventional energy industry front to protect RWEs & Vattenfalls assets in the coming debate.

        Without nuclear & without a profitable market for load following power plants, there is no future in power generation for E.On, EnBW or the large municipal/regional utilities.

        There are only two options:
        -a generous capacity market that makes load following power plants profitable
        -pushing inflexible power plants out of the market somehow (good for the energy transition)

        There certainly alot of efford by special interesst advocates right now to slow further investments in renewables down right now, which makes absolutly no sense from an economic point of view.

        There is a solar wildcard in all this, since the industrial price parity is a relativly new developement. There could be a non-FIT induced second solar boom that would (once again) create realities outside the controll of the conventional power copmanies (RWE, E.On,…)
        While you might say “but that makes no sense”, internalizing parts of the value creation and reducing the cost for 15-30% of the anual electricity demand* is an attractive micro-economic incentive for small & medium businesses (and households).


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