Renewable Energy Engineering 2023/24 EEE_6_REE
QUESTION 1 (40 marks)
a) Define the fill-factor (FF) and efficiency (\eta) of a solar cell. Give an expression for
the conversion efficiency relating with FF and other parameters for a solar cell
(6 marks)
device.
A 15% efficient, 100 W- Si solar cell module is operating at voltage 24 Volts under
standard AM1.5 illumination (1 kWm²). Calculate the area of the module and the
optimum load resistance connected across it.
(6 marks)
b) The I-V characteristics of an ideal p-n junction are given by $I = I_s - I_s[e^{\frac{eV}{kT}} - 1]$.
Show that the open circuit for an ideal solar cell is given approximately by $V_{OC} \approx \frac{kT}{q} ln(\frac{I_L}{I_s})$. Assuming that $V_{OC} \approx$ 1 V, what is the ratio $I_L/I_s$? What factors determine
the order of magnitude of $V_{OC}$? (Take T=300 K).
(6 marks)
c) A crystalline silicon PV cell, is subjected to the AM1.5, generates photo-current
density of 30 mA cm² having the saturation current density 2 x 10?? Am² at the
PV cell surface temperature of 300 K. The maximum power achieved was 170
Wm². Assume the short circuit current density is equivalent to the photo-current
density and input solar intensity at AM1.5 as 930 W/m². Determine:
i) The Zenith angle
ii) Open Circuit Voltage
iii) Fill Factor
iv) Conversion efficiency
[Given Boltzmann constant, k= 1.38 x 10?²³ J/K and electronic charge, e = 1.6x
10?¹? C]
(12 marks)
d) A PV system using 50 W, 12 V panels with 6 V, 125 Ah batteries is needed to
power a home with a daily load of 1700 Wh in a sunny location in Spain. System
voltage is 24 V. There is an average of 5 daylight hours at the location. Specify
the PV panel and storage size for the system using the Heuristic approach.
(10 marks)
