Comparison of Photovoltaic Module Performance Measurements.
Comparison of Photovoltaic Module Performance
Measurements.
(1334 K)
Fanney, A. H.; Davis, M. W.; Dougherty, B. P.; King, D.
L.; Boyson, W. E.; Kratochvil, J. A.
Journal of Solar Energy Engineering (Transactions of the
ASME), Vol. 128, No. 2, 152-159, May 2006.
Sponsor:
Department of Energy's National Nuclear Security
Administration, Washington, DC
Keywords:
photovoltaic module; photovoltaic systems; computer
simulation; economic factors; specifications; solar
cells; solar energy; temperature coefficients; air mass;
equations; energy sources
Abstract:
Computer simulation tools used to predict the energy
production of photovoltaic systems are needed in order
to make informed economic decisions. These tools require
input parameters that characterize module performance
under various operational and environmental conditions.
Depending upon the complexity of the simulation model,
the required input parameters can vary from the limited
information found on labels affixed to photovoltaic
modules to an extensive set of parameters. The required
input parameters are normally obtained indoors using a
solar simulator or flash tester, or measured outdoors
under natural sunlight. This paper compares measured
performance parameters for three photovoltaic modules
tested outdoors at the National Institute of Standards
and Technology (NIST) and Sandia National Laboratories
(SNL). Two of the three modules were custom fabricated
using monocrystalline and silicon film cells. The third,
a commercially available module, utilized
triple-junction amorphous silicon cells. The resulting
data allow a comparison to be made between performance
parameters measured at two laboratories with differing
geographical locations and apparatus. This paper
describes the apparatus used to collect the experimental
data, test procedures utilized, and resulting
performance parameters for each of the three modules.
Using a computer simulation model, the impact that
differences in measured parameters have on predicted
energy production is quantified. Data presented for each
module includes power output at standard rating
conditions and the influence of incident angle, air
mass, and module temperature on each module's electrical
performance. Measurements from the two laboratories are
in excellent agreement. The power at standard rating
conditions is within 1% for all three modules. Although
the magnitude of the individual temperature coefficients
varied as much as 17% between the two laboratories, the
impact on predicted performance at various temperature
levels was minimal, less than 2%. The influence of air
mass on the performance of the three modules measured at
the laboratories was in excellent agreement. The largest
difference in measured results between the two
laboratories was noted in the response of the modules to
incident angles that exceed
75DG.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899