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Title: Use of Pyranometers to Estimate PV Module Degradation Rates in the Field: Preprint

Abstract

This paper describes a methodology that uses relative measurements to estimate the degradation rates of PV modules in the field. The importance of calibration and cleaning is illustrated. The number of years of field measurements needed to measure degradation rates with data from the field is cut in half using relative comparisons.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1296611
Report Number(s):
NREL/CP-5D00-66498
DOE Contract Number:
AC36-08GO28308
Resource Type:
Conference
Resource Relation:
Conference: Presented at the 43rd IEEE Photovoltaic Specialists Conference, 5-10 June 2016, Portland, Oregon
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 47 OTHER INSTRUMENTATION; PV modules; degradation; calibration; field measurements

Citation Formats

Vignola, Frank, Peterson, Josh, Kessler, Rich, Mavromatakis, Fotis, Dooraghi, Mike, and Sengupta, Manajit. Use of Pyranometers to Estimate PV Module Degradation Rates in the Field: Preprint. United States: N. p., 2016. Web. doi:10.1109/PVSC.2016.7749764.
Vignola, Frank, Peterson, Josh, Kessler, Rich, Mavromatakis, Fotis, Dooraghi, Mike, & Sengupta, Manajit. Use of Pyranometers to Estimate PV Module Degradation Rates in the Field: Preprint. United States. doi:10.1109/PVSC.2016.7749764.
Vignola, Frank, Peterson, Josh, Kessler, Rich, Mavromatakis, Fotis, Dooraghi, Mike, and Sengupta, Manajit. 2016. "Use of Pyranometers to Estimate PV Module Degradation Rates in the Field: Preprint". United States. doi:10.1109/PVSC.2016.7749764. https://www.osti.gov/servlets/purl/1296611.
@article{osti_1296611,
title = {Use of Pyranometers to Estimate PV Module Degradation Rates in the Field: Preprint},
author = {Vignola, Frank and Peterson, Josh and Kessler, Rich and Mavromatakis, Fotis and Dooraghi, Mike and Sengupta, Manajit},
abstractNote = {This paper describes a methodology that uses relative measurements to estimate the degradation rates of PV modules in the field. The importance of calibration and cleaning is illustrated. The number of years of field measurements needed to measure degradation rates with data from the field is cut in half using relative comparisons.},
doi = {10.1109/PVSC.2016.7749764},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 8
}

Conference:
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  • This poster provides an overview of a methodology that uses relative measurements to estimate the degradation rates of PV modules in the field. The importance of calibration and cleaning is illustrated. The number of years of field measurements needed to measure degradation rates with data from the field is cut in half using relative comparisons.
  • Methodology is described that uses relative measurements to estimate the degradation rates of PV modules in the field. The importance of calibration and cleaning is discussed. The number of years of field measurements needed to measure degradation rates with data from the field is cut in half using relative comparisons.
  • Photovoltaic (PV) module degradation rate analysis quantifies the loss of PV power output over time and is useful for estimating the impact of degradation on the cost of energy. An understanding of the degradation of all current-voltage (I-V) parameters helps to determine the cause of the degradation and also gives useful information for the design of the system. This study reports on data collected from 12 distinct mono- and poly-crystalline modules deployed at the National Renewable Energy Laboratory (NREL) in Golden, Colorado. Most modules investigated showed < 0.5%/year decrease in maximum power due to short-circuit current decline.
  • To sustain the commercial success of photovoltaic (PV) technology it is vital to know how power output decreases with time. Unfortunately, it can take years to accurately measure the long-term degradation of new products, but past experience on older products can provide a basis for prediction of degradation rates of new products. An extensive search resulted in more than 2000 reported degradation rates with more than 1100 reported rates that include some or all IV parameters. In this paper we discuss how the details of the degradation data give clues about the degradation mechanisms and how they depend on technologymore » and climate zones as well as how they affect current and voltage differently. The largest contributor to maximum power decline for crystalline Si technologies is short circuit current (or maximum current) degradation and to a lesser degree loss in fill factor. Thin-film technologies are characterized by a much higher contribution from fill factor particularly for humid climates. Crystalline Si technologies in hot & humid climates also display a higher probability to show a mixture of losses (not just short circuit current losses) compared to other climates. The distribution for the module I-V parameters (electrical mismatch) was found to change with field exposure. The distributions not only widened but also developed a tail at the lower end, skewing the distribution.« less
  • We propose a method for increasing the frequency of data collection and reducing the time and cost of accelerated lifetime testing of photovoltaic modules undergoing potential-induced degradation (PID). This consists of in-situ measurements of dark current-voltage curves of the modules at elevated stress temperature, their use to determine the maximum power at 25 degrees C standard test conditions (STC), and distribution statistics for determining degradation rates as a function of stress level. The semi-continuous data obtained by this method clearly show degradation curves of the maximum power, including an incubation phase, rates and extent of degradation, precise time to failure,more » and partial recovery. Stress tests were performed on crystalline silicon modules at 85% relative humidity and 60 degrees C, 72 degrees C, and 85 degrees C. Activation energy for the mean time to failure (1% relative) of 0.85 eV was determined and a mean time to failure of 8,000 h at 25 degrees C and 85% relative humidity is predicted. No clear trend in maximum degradation as a function of stress temperature was observed.« less