Semiconductor devices. Consider a pnvjunction semiconductor device used as a solar cell. (a) Estimate the efficiency i; = Pom/Pin for a Si-based solar cell exposed to the sun's blackbody emission spectrum. Use T = 6000 K for the effective temperature of the Sun and 1.1 eV for the bandgap in Si. Hint: You can obtain the input power from Planck's law. The output power is given byPout : Q - E9 . The photon flux Q is defined by dividing Planck's distribution by the photon energy but you need to integrate over some appropriate range. (b) The maximum real efficiency is given by Kid's- (K. J 11:}? where F is the form factor, V}, is the open circuit voltage, Js is the short circuit current density. and {'3' : 1000 \"71112 is the solar irradiance on the Earth's surface. For a typical Sivbased solar cell. we have F = 0.7, v1, 2 0.6 V and .15 = 30 111A/c-1112. What is the maximum real efficiency of this cell? How does it compare with the intrinsic efficiency calculated earlier? (c) Residential daily consumption of electricity is 12.1 kilowatt~hours (kWh) per person in average. Given the efficiency computed above, estimate the area of a Si-based solar system that can make a single family home of 4 people completely selfsufficient. (Note: Assume that the system operates 12h per day, and that the excess energy accumulated during the day is kept for use overnight in some sort of storage system). Is this practical? (d) Now assume that the solar system can be installed for $3 per Watt, and that the energy storage solution costs $200/kWh. What is the upfront cost of this system? Assuming that the system performs with the efficiency calculated above for 20 years. compare this result with the cost of paying a conventional electrical bill at a rate of $0.12/kWh over the same period. Is the investment worth it