What the Duck?! Curve

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India has a very large power system with a total installed capacity of 258 GW. The Typical demand on the grid varies throughout the day peaking once in the morning around 125 GW and once in the evening around 135-140 GW. The intra day variation can be seen from the graph below.

National Power Demand NLDC

This further varies from day to day and season to season. Between themselves, the National Load Disptach Centers and various DISCOMs are responsible to ensure that maximum demand is met. Managing such a large grid with dramatic variations is both a technical as well as an operational challenge.

The situation becomes even more complicated when we introduce grid connected solar power into the equation. Solar power plants generate highly varying amounts of power throughout the day time depending on the amount of sunshine. The output resembles a bell curve which peaks around noon.

Now if we imagine solar power as a negative load on the national power grid, we can essentially calculate plot the net resulting national demand as below:

National Demand NLDC Post Solar

As per industry measures, national installed solar capacity has ramped up from 2.4 GW in 2014 to 8 GW in 2016 and is expected to cross 18 GW in early 2018. This graph plots the resulting demand on the national grid after adjusting for the supplied solar power.

Note how the required ramp up of demand from the national grid between 2:00 PM and 8:00 PM is becoming progressively steeper each year as we are connecting more solar power to the grid. This is the duck curve and its dilemma.

If you represent a utility or a power generation company, how does this impact your business?

5 thoughts on “What the Duck?! Curve

  1. The northern grid has more demand whereas southern grid is already surplus. Even though its now single grid in paper, practically north and south grids operate differently. Please visit a load despatch centre in west or south (LDC) and figure out the demand. Now approvals for net-metering projects in states of AP, Karnataka is very difficult. the answer comes from discom mentioning they have surplus power. this figure which you have mentioned only suits for Delhi/ norther part not for south. And moreover the National demand will not make logic from solar perspective.

    1. The point of this article is to explain the concept of the Duck curve with data drawn from NLDC and solar simulations. We hope to delve into more detail region wise on the push back being received from DISCOMs. More comments welcome.

  2. I think one way to flatten the Duck is solar + storage. The power demand peaks near the sunset period, where solar power starts to die. Storage can supply continuous and ‘dispatchable’ power after sunset which can reduce the load on the grid. This certainly opens up tremendous business possibilities for storage.
    Moreover, using energy efficient devices can help in flattening the Duck as well.

    1. Great point Laksh! That is why Lithium ion storage technologies hold so much promise- hopefully demand and policy will work together to bring down their price quickly.

      1. VRLA battery type storage applications are better because of cost prospective. and it is excellent for upto 10KW structure.

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