Increasing momentum around several different types of concentrating flat panel designs provides challenges with respect
to modeling energy harvest. While there have been several simulation models created for standard flat panel PV
modules, simulating low concentrating PV modules is more complex and less readily available. Specifically, since the
optical characteristics of each low concentrating module is different, the energy prediction model must incorporate an
optical model specific to the concentrator design.
A PV module energy production model is created using a solar irradiance model (combining HDKR, NREL data and
Meteonorm) and optical models for different panel types. Resulting energy production values are then correlated with
actual measurements to verify the model and methodology.
The simulation model is exercised across various geographic latitudes to illustrate how different module types can be
most useful in specific locations. The results show an illustrative guideline for predicting module production and
therefore selection. The model is specific to energy production and is useful to compare different module technologies
under various conditions.
Key findings include the following: optics engineers should consider application related issues when modeling various
concentrating flat panel designs; computer scientists working on energy harvest software (e.g., PV Watts) need to
include optics issues related to each concentrating flat panel; aberrations in climate databases can cause significant
biases in energy harvest output; and system installers should follow manufacturer guidelines when installing
concentrating flat panels.
Cost reduction is a major focus of the solar industry. Thin film technologies and concentration systems are viable ways
to reducing cost, with unique strengths and weakness for both.
Most of the concentrating PV work focuses on high concentration systems for reducing energy cost. Meanwhile, many
believe that low concentrators provide significant cost reduction potential while addressing the mainstream PV market
with a product that acts as a flat panel replacement. This paper analyzes the relative benefit of asymmetric vs. symmetric
optics for low-concentrators in light of specific PV applications.
Symmetric and asymmetric concentrating PV module performance is evaluated using computer simulation to determine
potential value across various geographic locations and applications. The selected optic design is modeled against
standard cSi flat panels and thin film to determine application fit, system level energy density and economic value.
While symmetric designs may seem ideal, asymmetric designs have an advantage in energy density. Both designs are
assessed for aperture, optimum concentration ratio, and ideal system array configuration. Analysis of performance across
climate specific effects (diffuse, direct and circumsolar) and location specific effects (sunpath) are also presented.
The energy density and energy production of low concentrators provide a compelling value proposition. More
significantly, the choice of optics for a low concentrating design can affect real world performance. With the goal of
maximizing energy density and return on investment, this paper presents the advantages of asymmetric optic
concentration and illustrates the value of this design within specific PV applications.