Part A) The PV panel 185W NU-185 (E1) is formed by 48 solar cells connected in series, divided in three sets of 16 cells with a by-pass diode, as shown in fig.1. Its current-voltage curve under STC conditions is shown in fig. 1b.

a)

b)

fig. 1. a) PV panel configuration, b) I-U curve

Considering the I-U curve shown, estimate (Ut=0.026V):

Q1) The diode ideality factor of one solar cell, n.
n=

Q2) The the dark-saturation current of one solar cell, Is [uA].
Is= [uA]

With the above PV panel, serie and parallel connections were done as shown in Fig.2. Unfortunately, due to some miscalculations, these sets of PV panels were placed too close to a surrounding tree. This caused a shading effect in the PV panels. In the figure below is shown one example of 100% shading in one group of 16 solar cells in only one PV panel. In Fig. 3, the results of several types of shading effects are shown.

a)                                                                                        b)

Fig. 2. a) Series connection of 3 PV panels, b) Parallel connection of 3 PV panels.

Please identify the curves corresponding to each case. Just type the letter of the curve as “a” and not as “a)”.

A 100% shading in one group of 16 solar cells in only one PV panel.
Q3) Series-connection case= [just type a, b, c, e or f]

Q4) Parallel-connection case= [just type a, b, c, e or f]

A 100% shading in one group of 16 solar cells in the three PVs panels.
Q5) Series-connection case= [just type a, b, c, e or f]

Q6) Parallel-connection case= [just type a, b, c, e or f]

A 100% shading in two groups of 16 solar cells in only one PV panel.
Q7) Series-connection case= [just type a, b, c, e or f]

Q8) Parallel-connection case= [just type a, b, c, e or f]

Part B) The 1 diode 5 parameter model of a solar cell is shown in Fig.4 .

Fig.4

Identify the correct answer:

Q9) The Ipv source represents:

 The diode dark-saturation current.
 The leakage currents within the solar cell.
 The photo-generated current.

Q10) The shunt Rp resistance represents:

 The leakage currents withing the solar cell.
 The influence of the electric contacts.
The voltage drop due to the increase of temperature.

Q11) The series Rs resistance represents:

 The leakage currents withing the solar cell.
 The influence of the electric contacts.
 The voltage drop due to the increase of temperature.

Q12) When the temperature increases and the irradiance remains the same:

 The photo-generated current slightly increases.
 The open-circuit voltage increases.
 The short-circuit current decreases.