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Title: Low irradiance losses of photovoltaic modules

Here, the efficiency of a photovoltaic cell/module changes, as the intensity of incident irradiance decreases, in a non linear way and these changes are referred to as low irradiance losses. In this study data from field experiments, developed and organized by the National Renewable Energy Laboratory, are used to evaluate the low irradiance losses for a variety of module technologies. The results demonstrate that the ratio of the normalized power divided by the normalized short circuit current provide a good measure of the module's low light efficiency losses after both the maximum power and the short circuit current are adjusted for temperature effects. The normalized efficiencies determined through the field data, spanning for several months, are in good agreement with those determined under controlled conditions in a solar simulator. An analytical relation for the normalized efficiency is proposed based on existing formulation for the fill factor. Despite the approximate nature of the fill factor relation, this approach produces reliable results. It will be shown that a normalized efficiency curve can be used to extract information on the series and shunt resistances of the PV module and that the shunt resistance as a function of solar irradiance can be studied. Alternately,more » this formulation can be used to study the low irradiance losses of a module when the internal resistances are known.« less
 [1] ;  [2] ;  [3]
  1. Technological Educational Institute of Crete, Crete (Greece)
  2. Univ. of Oregon, Eugene, OR (United States)
  3. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0038-092X
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Solar Energy
Additional Journal Information:
Journal Volume: 157; Journal Issue: C; Journal ID: ISSN 0038-092X
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
14 SOLAR ENERGY; photovoltaic modules; efficiency; fill factor; series resistance; shunt resistance; low irradiance losses
OSTI Identifier: