Imagine we are trying to design a solar panel for use on the exoplanet "Proxima Centauri b".
This planet orbits the star Proxima Centauri, which has a surface temperature of 2770 °C, and
the planet receives a total illumination (in terms of power density) of about 17% of that of
earth, and has a surface temperature of -40 °C (all estimated).
a. Calculate and plot the spectral irradiance from the star on the planet, in terms of [W/(m2
nm)] vs wavelength [nm]. Hint – use Plank’s law in the form Sλ from lecture 5 to get
the overall shape of the distribution and the above power density value to normalize
the plot.
b. What would be the detailed balance efficiency limit for this spectrum? Show a plot of
this new limit as a function of band gap. What is the ideal band gap for a "Proxima
Centari cell"? You may neglect the influence of the sky fraction (i.e. calculate the limit
2 of 2 for full concentration). Hint: You can assume the ideal operating potential is at 0.9*