Weather-Corrected Performance Ratio

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Description

Photovoltaic (PV) system performance depends on both the quality of the system and the weather. One simple way to communicate the system performance is to use the performance ratio (PR): the ratio of the electricity generated to the electricity that would have been generated if the plant consistently converted sunlight to electricity at the level expected from the DC nameplate rating. The annual system yield for flat-plate PV systems is estimated by the product of the annual insolation in the plane of the array, the nameplate rating of the system, and the PR, which provides an attractive way to estimate ... continued below

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22 p.

Creation Information

Dierauf, T.; Growitz, A.; Kurtz, S.; Cruz, J. L. B.; Riley, E. & Hansen, C. April 1, 2013.

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This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. It has been viewed 23 times . More information about this report can be viewed below.

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Description

Photovoltaic (PV) system performance depends on both the quality of the system and the weather. One simple way to communicate the system performance is to use the performance ratio (PR): the ratio of the electricity generated to the electricity that would have been generated if the plant consistently converted sunlight to electricity at the level expected from the DC nameplate rating. The annual system yield for flat-plate PV systems is estimated by the product of the annual insolation in the plane of the array, the nameplate rating of the system, and the PR, which provides an attractive way to estimate expected annual system yield. Unfortunately, the PR is, again, a function of both the PV system efficiency and the weather. If the PR is measured during the winter or during the summer, substantially different values may be obtained, making this metric insufficient to use as the basis for a performance guarantee when precise confidence intervals are required. This technical report defines a way to modify the PR calculation to neutralize biases that may be introduced by variations in the weather, while still reporting a PR that reflects the annual PR at that site given the project design and the project weather file. This resulting weather-corrected PR gives more consistent results throughout the year, enabling its use as a metric for performance guarantees while still retaining the familiarity this metric brings to the industry and the value of its use in predicting actual annual system yield. A testing protocol is also presented to illustrate the use of this new metric with the intent of providing a reference starting point for contractual content.

Physical Description

22 p.

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  • Report No.: NREL/TP-5200-57991
  • Grant Number: AC36-08GO28308
  • DOI: 10.2172/1078057 | External Link
  • Office of Scientific & Technical Information Report Number: 1078057
  • Archival Resource Key: ark:/67531/metadc838500

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Office of Scientific & Technical Information Technical Reports

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Creation Date

  • April 1, 2013

Added to The UNT Digital Library

  • May 19, 2016, 9:45 a.m.

Description Last Updated

  • April 4, 2017, 2:09 p.m.

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Dierauf, T.; Growitz, A.; Kurtz, S.; Cruz, J. L. B.; Riley, E. & Hansen, C. Weather-Corrected Performance Ratio, report, April 1, 2013; Golden, Colorado. (digital.library.unt.edu/ark:/67531/metadc838500/: accessed August 18, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.