ECE 414a/514a
Practice Problem Set #5
1. Compute the global irradiance at 9:30 AM on 20 April (day 110) at latitude of
+30o with the receiver horizontal and facing the sun for maximum collection.
Assume that the receiver is facing due South for the horizontal case.
2. Using the data from Table 20.1 for latitude of 30o compute the global horizontal
irradiance at 1:30PM solar time on 15 April. The measured global daily
irradiation on that date is 6200 Wh/m2. Receiver is facing South.
3. Modify the estimates for direct, diffuse, and reflected irradiance for the values
obtained in problem 2 if the receiver is tilted at 25o, 35o, and 45o to the horizontal.
4. Assume that the effect of the parallel resistance is negligible, the light generated
current = Isc, and
exp / 1
st
V IR V
. A PV generator is rated at 2400W
(STC), made up of 60 modules, arranged 10 in series and 6 in parallel. Geff = 710
W/m2 and Ta = 35oC. The modules have the following STC characteristics:
* * *
5.5 , 22.4 , 96
SC oc M
I A V V P W
. Each module has 40 cells connected in series
with a NOCT = 45oC.
a. Determine the characteristics of the cells that make up the generator under
STC. Also estimate
*
s
R
b. Determine the temperature of the cells under the operating conditions.
c. Determine the characteristics of the cells (Isc, Voc, FF) under the operating
conditions.
d. Determine the characteristic curve of the generator (IG, VG)
e. Determine the maximum power point
5. Make a plot of the I-V characteristic of a PV cell with short circuit current of
3.5A and a reverse saturation current of 1.2 nA operating at room temperature
(300oK). What is the open circuit voltage?
6. Consider two solar cells. Cell #1 has a short circuit output current of 3.2A with
full one sun illumination and an open circuit voltage of 0.55V. Cell #2 is shaded
and has a short circuit output current of 1.6A and also has an open circuit voltage
of 0.55V.
a. Draw a circuit diagram for identical two solar cells (Cell #1) connected in
series with a short circuit output connection.
b. Using the I-V diagram below graphically determine the new short circuit
current for the two cells in series.
