6.1. Electricity from solar PV: An upper-bound on conversion efficiency In Assignment #1, we computed the spectral distribution of solar energy, assuming that the sun behaved as a blackbody at T = 5800 K. Use that information, along with the key ideas in Lecture #16 of the reader (see Figure 8), to determine the upper bound efficiency for converting solar energy to electricity in a silicon photovoltaic cell. The key points are (i) that the useful energy per photon equals the band-gap energy, which is 1.8 10 -19 J; and (ii) photons that possess less than the band-gap energy do not produce electricity