The efficiency of a TPV converter is dependent on many parameters. A spreadsheet model of a TPV converter has been developed to study the effects of these parameters, and to estimate whether a TPV converter would be practical with reasonable parameter values. The model was built with two Multiplan(8) spreadsheets. The first, SPECTRUM, computes values which are dependent on the solar cell material (e.g., Si) and on the temperature of the radiator. The second, TPVMODEL, uses the values from SPECTRUM to compute masses and efficiencies of the whole converter system. Table 2.3-2 is an example of part of SPECTRUM, using silicon cells and a 2300 I radiator. TABLE 2.3-2 USABILITY OF 2300 K SPECTRUM FOR SILICON CELLS SPECTRUM uses a numerical calculation of a blackbody spectral power distribution. This distribution is integrated from the cell material’s band-gap energy to infinity to give an estimate of I g, the spectral intensity which could be converted to electron-hole pairs if the cells’ quantum efficiency were unity. Another section integrates the spectral intensity times the ratio of the band-gap energy to photon energy to give an estimate of I_u, the potential electron-hole intensity that could be converted to electricity. These two values are divided by the total radiant intensity of the radiator to yield f g, the fraction of the total power which can ideally be absorbed as electron-hole pairs, and f^u, the fraction of electron-hole pair energy which can ideally be converted to electricity. Table 2.3-3 is an example of TPVMODEL, using the SPECTRUM model in Table 2.3-2.
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