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Home / Technical Articles / Why we find wind energy delivery factor important?
Why we find Wind Energy Delivery Factor important?
Why we find Wind Energy Delivery Factor important? (photo by Bill Doyle via Flickr)

Economic Performance Measure

The key economic performance measure of a power plant is the electrical energy it delivers over the year. Not all power produced is delivered to the paying customers. A fraction of it is used internally to power the control equipment, meeting the power equipment losses and for the housekeeping functions such as lighting.

In a typical wind farm (or photovoltaic park as well), about 90 percent of the power produced is delivered to the customers, and the remaining is self-consumed for the plant operation.

The quantity of energy delivered depends on the peak power capacity of the site and how fully that capacity is utilized over every hour of the year.

The normalized measure of the power plant performance is the Energy Delivery Factor (EDF).

It is defined as the ratio of the electrical energy delivered to the customers to the energy that can be delivered by the plant if it could be operated at the fully installed capacity during all 8,760 hours of the year, that is as follows:

Average annual EDF

Since the load power varies over the time, the EDF takes the integral form:

EDF integral form


Pm – Plant capacity (the maximum power the plant can deliver)

Po – Power delivered to the customers at any time t

The EDF is usually determined by bookkeeping the sum of the energy delivered over a continuous series of small discrete time intervals, that is as follows:

Average annual EDF


Pavg – average power delivered over the small time interval ∆t.

The EDF is a figure of merit that measures how hard the plant is utilized to deliver the maximum possible energy.

Not only does it include the energy conversion efficiencies of various components, it also accounts for the reliability, maintainability, and availability of the overall plant over the entire year.

Wind Farm in Cedar Creek, Colorado, USA
Wind Farm in Cedar Creek, Colorado, USA (photo by BP Images via Flickr)

The EDF is useful in comparing the economic utilization of one site over the other, or the annual performance of a given site. Wind plants operate with the annual average EDF around 30 percent, with some plants reporting EDF as high as 40 percent.

This compares with 40 to 80 percent for the conventional plants. The base load plants operate at the higher end of the range.

The wind farm energy delivery factor varies with season and that must be taken into account.

Resource: Wind and solar power systems – M. K. Patel

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Edvard Csanyi

Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV/MV switchgears and LV high power busbar trunking (<6300A) in power substations, commercial buildings and industry facilities. Professional in AutoCAD programming.


  1. aletourneau
    Apr 15, 2013

    Edvard- I cannot seem to find a rendition of the article with the formulae. In all versions I can find the formulas are replaces with the EEP LOGO. can I get a download of the article with the formulae?

    • Edvard
      Apr 15, 2013

      Hi Aletourneau,

      This is very strange. Try clearing cookies in your browser. Pics in this article as well as in all other technical articles are present.

      However, try visiting RSS archive of this article here:

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