19.6
19.1
19.2
(a)
(b)
(c)
(d)
19.3
19.4
(a)
(b)
(c)
(d)
19.5
Exercises
Calculate the maximum power of a solar cell having current and voltage values of I MPP = 30 mA and V MPP =
0.7 V, respectively, at the maximum power point.
Consider an ideal solar cell, with open-circuit voltage V oc , short circuit current I sc , maximum power point
voltage V MPP and maximum power point current I MPP . Which resistance should the load have for the cell to
operate at its maximum?
V OC /I SC
V OC /I MPP
V MPP /I SC
V MPP /I MPP
Consider a PV module with the following parameters as measured at STC (standard testing conditions): V OC =
50 V, I SC = 4.5 A, I MPP = 4.0 A, V MPP = 40 V, η = 18%. Suppose that the module is not connected to an MPPT
device, and is instead directly connected to a purely resistive, variable load R. The load R can be tuned to give a
resistance between 0 and 1 kΩ. At which value of resistance will you keep the load to derive maximum power
from the PV module under STC conditions?
Consider typical I-V and P-V curves of a solar module as shown Figure 19.2. Which of the following
statements are true? (More solutions possible.)
For any set of irradiance and temperature conditions, P MPP > V OC × I SC .
With the rest of the conditions remaining the same, if the irradiance falling on the PV module uniformly
increases such that the new P-V curve has an MPP at
, then
> P MPP .
The rest of the conditions remaining the same, if the irradiance falling on the PV module uniformly
increases such that the new P-V curve has an MPP at
, then
< P MPP .
For V = V MPP , we have dP/dV = 0.
Consider that an MPPT based on the perturb and observe algorithm is connected to a PV module with the P-V
curve shown in Figure 19.28. The MPPT has two different modes of operation: coarse and fine. A coarse
adjustment corresponds to a voltage change of ±5 V, while a fine adjustment corresponds to a voltage change of
±1 V.
If the MPPT has taken a step such that a change in voltage has led to an increase in power, then the next step is
a coarse adjustment in the same direction as the previous step.
On the other hand, if the MPPT has taken a step such that a change in voltage has led to a decrease in power,
then the next step is a fine adjustment in the opposite direction to the previous step.
Consider that the module is currently operating at point A, corresponding to a voltage of 8V, and that the MPPT
is just about to take a coarse step by increasing the voltage. If the irradiance and temperature conditions are
maintained, i.e. the P-V curve remains the same, how many steps will the MPPT take before it reaches the
MPP?
19.1
19.2
(a)
(b)
(c)
(d)
19.3
19.4
(a)
(b)
(c)
(d)
19.5
Exercises
Calculate the maximum power of a solar cell having current and voltage values of I MPP = 30 mA and V MPP =
0.7 V, respectively, at the maximum power point.
Consider an ideal solar cell, with open-circuit voltage V oc , short circuit current I sc , maximum power point
voltage V MPP and maximum power point current I MPP . Which resistance should the load have for the cell to
operate at its maximum?
V OC /I SC
V OC /I MPP
V MPP /I SC
V MPP /I MPP
Consider a PV module with the following parameters as measured at STC (standard testing conditions): V OC =
50 V, I SC = 4.5 A, I MPP = 4.0 A, V MPP = 40 V, η = 18%. Suppose that the module is not connected to an MPPT
device, and is instead directly connected to a purely resistive, variable load R. The load R can be tuned to give a
resistance between 0 and 1 kΩ. At which value of resistance will you keep the load to derive maximum power
from the PV module under STC conditions?
Consider typical I-V and P-V curves of a solar module as shown Figure 19.2. Which of the following
statements are true? (More solutions possible.)
For any set of irradiance and temperature conditions, P MPP > V OC × I SC .
With the rest of the conditions remaining the same, if the irradiance falling on the PV module uniformly
increases such that the new P-V curve has an MPP at
, then
> P MPP .
The rest of the conditions remaining the same, if the irradiance falling on the PV module uniformly
increases such that the new P-V curve has an MPP at
, then
< P MPP .
For V = V MPP , we have dP/dV = 0.
Consider that an MPPT based on the perturb and observe algorithm is connected to a PV module with the P-V
curve shown in Figure 19.28. The MPPT has two different modes of operation: coarse and fine. A coarse
adjustment corresponds to a voltage change of ±5 V, while a fine adjustment corresponds to a voltage change of
±1 V.
If the MPPT has taken a step such that a change in voltage has led to an increase in power, then the next step is
a coarse adjustment in the same direction as the previous step.
On the other hand, if the MPPT has taken a step such that a change in voltage has led to a decrease in power,
then the next step is a fine adjustment in the opposite direction to the previous step.
Consider that the module is currently operating at point A, corresponding to a voltage of 8V, and that the MPPT
is just about to take a coarse step by increasing the voltage. If the irradiance and temperature conditions are
maintained, i.e. the P-V curve remains the same, how many steps will the MPPT take before it reaches the
MPP?