AIM: To plot the I – V characteristics of solar cell and determine fill factor.
In this post, practical of I – V characteristics of solar
cell and determination of fill factor method is given.
Theory
The relation between solar cell voltage and current is given by
Id = Io ( eqv/kT
– 1 )
Where
Id = diode current
q = Electron charge = 1.602 × 10 –
19 Coulomb
k = Boltzmann’s constant = 1.381 ×
10 – 23 Joule / Kelvin
T = Junction Temperature in Kelvin
Id = Diode current
Io = Reverse saturation
current
V = Voltage across diode terminal
At standard room temperature of 25
0C = 273.15 + 25 = 298.15 K
q/kT = (1.602 × 10 – 19
)/(1.381 × 10 – 23 )(298.15)
= 38.90
Id = Io ( e38.90v – 1 )
Solar cell: Open circuit and short circuit
Actual solar cell in its equivalent circuit under two conditions are given here. When the solar cell terminals are short circuited, the current flows through lead or wire are ISC (short circuit current). When the leads of the solar cell are shorted together, no current flows through diode as voltage across solar cell Vd = 0. Similarly when load is open circuited and measure voltage across solar cell, no current flow through load and it is open circuited VOC (open circuited voltage).
Circuit Diagram
Instruments / Equipment Required
- Solar cell / Solar panel
- DC milli ammeter
- Voltmeter
- Multimeter
- Patch cords
- Light source
Procedure
- Place the light source and solar cell in the opposite direction
- Switch on the light source.
- Make the light intensity to some fixed value.
- Make the connection as shown in the figure.
Short circuit condition
- Short the load resistance or make the load resistor is equal to zero and measure the current passing through load resistor.
- It is short circuit current ISC = _____________
Open circuit condition
- Make the ammeter circuit open circuited and measure voltage across solar cell
- It is open circuit voltage Voc = ____________
- Again, the circuit connection is done as per diagram.
- Vary the load resistor in step from low value to large value / large value to low value and note down the reading of voltmeter and ammeter.
- Plot graph between output voltage and current, taking voltage on x axis and current on y axis.
- In the I – V characteristics of solar cell, Voc and Isc are the end point of the solar cell characteristics in x axis and y axis respectively. Note down the reading of Vm and Im from the readings and show on the graph. The point corresponding to Vm and Im on I – V curve is known as maximum power point.
Observation table
|
Sr. No. |
Resistor |
Voltage |
Current |
|
1 |
|
|
|
|
2 |
|
|
|
|
3 |
|
|
|
|
4 |
|
|
|
|
5 |
|
|
|
|
6 |
|
|
|
Graph of IV Characteristics of solar cell
The I – V characteristics of solar cell is similar to that
shown in the figure.
Calculation
From the graph, Vm = ______ V & Im
= _________ mA
Maximum useful power = Vm × Im
Ideal Power = Voc × Isc = _________ mW
Fill Factor = (Vm × Im) / (Voc
× Isc)
Conclusion
The fill factor is determined by I – V characteristics of solar cell. The fill factor is an important parameter to determine the efficiency of solar cell. Higher the fill factor, more rectangular the I – V curve.
You may also like to read these articles
Importance
of Load Factor and Diversity Factor
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