Lateral spectrum splitting concentrator photovoltaics: direct measurement of component and submodule efficiency

Abstract

To achieve high energy conversion efficiency, a solar module architecture called lateral spectrum splitting concentrator photovoltaics (LSSCPV) is being developed. LSSCPV can concentrate available sunlight and laterally split a single beam into bands with different spectra for absorption by different solar cells with band gaps matched to the split spectrum. Test assemblies of a sample LSSCPV architecture were constructed, each of which contains four p–n junctions and two optical pieces. Independent experiments or simulations had been implemented on the components but by using optimal assumptions. In order to examine the actual performances of all the components, which are dependent on each other and the light source, direct outdoor measurements were made. A set of self‐consistent efficiency definitions was articulated and a test bed was developed to measure the parameters required by the efficiency calculation. By comparing the component efficiency items derived from the outdoor measurement and the expected values based on independent simulations, the potential opportunities for efficiency improvement are determined. In the outdoor measurement at the University of Delaware, the optical component demonstrated 89·1% efficiency. Additional assemblies were tested at the National Renewable Energy Laboratory. One assembly demonstrated 36·7% submodule efficiency, which compares favorably with the 32·6% previously reported verified submodule efficiency. Copyright © 2011 John Wiley & Sons, Ltd.

High-Concentrator Photovoltaic Power Plants: Energy Balance and Case Studies

“…A module based on new optical configurations to achieve ultra-high concentration levels and to decrease the dimensions of current HCPV modules has been proposed [25]. In addition, the use of optical devices to split the spectral distribution has already showed its potential to create modules with greater efficiencies [2,33].…”

Thin photovoltaic modules at ultra high concentration

“…The use of microcells reduces the optical path of the module, so, instead of being around 40-60 cm deep HCPV module, a typical depth for modules with concentration greater than x1000, Semprius' module is only 6.6 cm deep. Also, the use of optical devices to split the spectral distribution has already demonstrated its potential to get modules with higher efficiencies [9,10]. Others possible designs are continuously being discussed by the scientific community in order to get more competitive modules.…”

Reflection hologram solar spectrum-splitting filters

“…Deviation from the designed angle ( Fig. 1(b)) will result in shift of the reflection spectral band [11,13]. Depositing the dichroic filter on a curved substrate [4] can improve the spectral matching to a spherical wavefront however it will result in an increase in fabrication difficulty and cost.…”

“…Top cell thinning is used to reduce the current-mismatch [2] however it also introduces spectral mismatch for some of the light due to incomplete absorption. Spectrum-splitting approach employs optics to separate different spectral components onto band-gap matched junctions [1,[3][4][5][6][7][8][9][10][11][12][13]. This expands the selection of materials and makes it possible to use less complicated PV cell fabrication techniques.…”

“…In addition, light-trapping can be incorporated on each junction through surface modifications and adding ultra-trapping filters [14] without affecting the rest of the system. Dichroic filters are commonly used in different spectrum-splitting optical system designs [1,4,6,[8][9][10][11][12][13]. They have advantages such as high optical efficiency, well defined reflection band and low polarization dependence.…”