Practical considerations in tandem cell modeling

Wanlass, M. W.; Emery, Keith; Gessert, T. A.; Horner, G.S.; Osterwald, C.R.; Coutts, T. J.

doi:10.1016/0379-6787(89)90028-8

Cited by 64 publications

(29 citation statements)

References 2 publications

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“…In the field, however, the operating temperature of solar cell receivers is not constant and varies throughout each day and year as atmospheric conditions change. These changes in temperature significantly affect the calculation of the energy yield, mainly due to the effect of the temperature on the V oc [11]. Other authors have taken this into account by modeling the variations in the solar cell parameters with the temperature [3], [12].…”

Section: Performance Map Measurement Techniquementioning

confidence: 99%

Optimization of Multijunction Solar Cells Through Indoor Energy Yield Measurements

García

McMahon

Steiner

et al. 2015

IEEE J. Photovoltaics

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Abstract-The variability of the solar spectra in the field may reduce the annual energy yield of multij unction solar cells. It would, therefore, be desirable to implement a cell design procedure based on the maximization of the annual energy yield. In this study, we present a measurement technique to generate maps of the real performance of the solar cell for a range of light spectrum contents using a solar simulator with a computer-controllable spectral content. These performance maps are demonstrated to be a powerful tool for analyzing the characteristics of any given set of annual spectra representative of a site and their influence on the energy yield of any solar cell. The effect of luminescence coupling on buffering against variations of the spectrum and improving the annual energy yield is demonstrated using this method.

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Section: Performance Map Measurement Techniquementioning

confidence: 99%

Optimization of Multijunction Solar Cells Through Indoor Energy Yield Measurements

García

McMahon

Steiner

et al. 2015

IEEE J. Photovoltaics

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“…However, theoretical efficiencies calculated from the one-dimensional solution 1,[12][13][14][15][16][17] are lower than the detailed balance efficiency limits because the one-dimensional model neglects photon recycling.…”

Section: One-dimensional-transport Modelmentioning

confidence: 99%

“…1,[7][8][9][10][11][12][13][14][15][16] As discussed below, the detailed balance approach yields a smaller J o , and, therefore, a higher efficiency than the ''standard'' solution to the one-dimensional problem. Theoretical efficiencies based on empirical data tend to reflect realistic, rather than ideal, efficiencies.…”

Section: Theoretical Modelsmentioning

confidence: 99%

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A comparison of theoretical efficiencies of multi‐junction concentrator solar cells

Kurtz

Myers

McMahon

et al. 2008

Progress in Photovoltaics

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Champion concentrator cell efficiencies have surpassed 40% and now many are asking whether the efficiencies will surpass 50%. Theoretical efficiencies of >60% are described for many approaches, but there is often confusion about ''the'' theoretical efficiency for a specific structure. The detailed balance approach to calculating theoretical efficiency gives an upper bound that can be independent of material parameters and device design. Other models predict efficiencies that are closer to those that have been achieved. Changing reference spectra and the choice of concentration further complicate comparison of theoretical efficiencies. This paper provides a side-by-side comparison of theoretical efficiencies of multijunction solar cells calculated with the detailed balance approach and a common one-dimensional-transport model for different spectral and irradiance conditions. Also, historical experimental champion efficiencies are compared with the theoretical efficiencies. Copyright # 2008 John Wiley & Sons, Ltd. INTRODUCTIONAs the world's interest in renewable energy has increased, the investment in solar has also grown. New approaches to achieving high efficiencies have been proposed by numerous groups. Sometimes these new approaches are described as having a theoretical efficiency >60%. Will these new cells be superior to today's cells, which have now surpassed 40%? 1 Predicting the answer to this question requires two steps: (1) when comparing the theoretical efficiencies of existing and new approaches, the same methodology must be used for both, and (2) an assessment should be made of how close the experimental efficiency may, ultimately, approach the theoretical efficiency for each case. The first step is obvious, but is often neglected, resulting in comparison of numbers that were derived in different ways. When making such comparisons, the choice of the methodology is much less important than the consistency of the methodology. The second step is aided by a review of the efficiencies that have been achieved so far.Over the years, many studies have presented theoretical multi-junction solar cell efficiencies as a function of the materials' band gaps. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] In general, no two studies use exactly the same assumptions, resulting in a range of theoretical efficiencies. The efficiencies are especially dependent on the conditions (spectrum, concentration, and temperature). Concentrating the sunlight to the maximum value ($46 000 suns) results in theoretical efficiencies 10-20% (absolute) higher than the corresponding one-sun efficiencies. 4 Changing the spectrum has a smaller effect (typically 1-4% absolute). 17 The choice of the theoretical model, or assumptions used in the model, also affects the calculated efficiency. Marti et al. compared two of the most common models. 18 They defined a ''standard'' model using Shockley's diode equation, modeling a one-dimensional p-n junction with appropriate values for surface recombination, layer thicknesses, etc. They co...

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“…Some investigators have proposed different methods to obtain the parameters of the subcells by making different assumptions and simplifications. Examples of extraction methods based on the SEM scheme can be found in the literature [46,55,59,[66][67][68] as can results from those based on the DEM scheme [59,[69][70][71]. It is important to note that these studies usually estimate the parameters at a particular set of operating conditions.…”

Section: Influence Of Optical Concentrationmentioning

confidence: 99%

Multijunction Concentrator Solar Cells: Analysis and Fundamentals

Férnández

García‐Loureiro

Smestad

2015

High Concentrator Photovoltaics

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Multijunction (MJ) concentrator solar cells are primarily constructed of III-V semiconductor materials. The high solar-conversion efficiencies of these devices are dependent on precise control of growth conditions using one of several techniques such as molecular beam epitaxy, metal organic chemical vapour, or metal organic vapour-phase epitaxy deposition. The use of several junctions in an MJ tandem stack allows these devices to achieve efficiencies that are not possible for single-junction devices. Their behaviour is consequently complex, but it can be understood through an examination of the external quantum efficiency and the temperature dependence of each cell in the stack. This chapter lays out a systematic approach for understanding the spectral and temperature dependence of the overall MJ device by way of consideration of its component subcells. The efficiency of the cell as a function of temperature and concentration is described for both lattice-matched and metamorphic triple-junction (TJ) solar cells. The electrical characteristics and current-voltage curves are described from these considerations, and the performance of MJ solar cells under real operating conditions are then presented by considering a term describing the overall thermal factor and another term for the spectral factor. These terms can be understood from the background presented in the previous sections. Finally, the power output for the complete cell incorporated into a Fresnel lens based high-concentration photovoltaic system is presented for a particular geographic location using meteorological data.

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Practical considerations in tandem cell modeling

Cited by 64 publications

References 2 publications

Optimization of Multijunction Solar Cells Through Indoor Energy Yield Measurements

Optimization of Multijunction Solar Cells Through Indoor Energy Yield Measurements

A comparison of theoretical efficiencies of multi‐junction concentrator solar cells

Multijunction Concentrator Solar Cells: Analysis and Fundamentals

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