photovoltaic energy conversion and sustainable energy

Written Part:
Q1. In Jan 2004 NASA's Mars Exploration Rover landed on the surface of Mars in search of answers about the history of water on the planet
(a) What is the solar irradiance (Wm^-2) entering the mars atmosphere, knowing R_sun=696 Mm, T_sun=5762 K, r_mars=230 Gm, σ=5.67x1^0-8 Wm^-2K^-4?
(b) What is the solar irradiance on the horizontally oriented solar panels (n=0°) of the Mars rover when the sun is in the zenith (z=0°), using the following properties of the Mars atmosphere: optical thickness αd=0.5 and s=0.8?
(c) The rover gets its energy from 1.3m² of solar cells with 27.5% overall conversion efficiency and it needs 100 W electrical power to drive. Calculate the direct, indirect, and total irradiation (Wm^-2) as well as the electrical output power when z=55° and panel is tilted towards the sun with n=10°. Will it be able to drive?

A1. 
(a) Calculate dilution factor, f, then get solar irradiance by Q=fσT⁴
(b) Calculate direct, indirect, and total irradiance.
(c) Calculate direct, indirect, and total irradiance and compare with Q_tot from η=W/Q_totA.

Q2. For the study of solar conversion we know that the spectral distribution n(E) follows from the emissivity ε(E), the number of photon modes h(E)dE, and the occupation probability f(E).
(a) Explain the greybody spectrum. What is emissivity?
(b) Derive h(E).
(c) Show that you can obtain the photon occupation probability from the electron occupation probability.

A2. See long derivation in course notes.

Q3. Forgot. Something about tandem cells and fill factors and output powers.

Q4. All about the window effect for heterojunction solar cells.
(a) Define the general current efficiency including all necessary parameters.
(b) Calculate the current efficiency as a function of u=amt. of light that can be absorbed in layer 2/amt. of light that can be absorbed in layer 1.
(c) Explain how the window effect comes to take place from (b).
(d) Sketch a graph of the current efficiency as a function of u.

A4. See long derivation in course notes.

Oral Part:
Q1. Derive and explain the equation for calculating a planet's temperature from the sun's temperature.
A1. See derivation in course notes.

Q2. Derive the (3) factors that affects the absolute efficiency, η^*, of a solar cell.
A2. See derivation in course notes.

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