Perforamnce of IV Characteristics of Solar Cell

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

I_d = I_o ( e^qv/kT – 1 )

Where

I_d = 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

I_d = Diode current

I_o = 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

I_d = I_o ( e^38.90v – 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 I_SC (short circuit current). When the leads of the solar cell are shorted together, no current flows through diode as voltage across solar cell V_d = 0. Similarly when load is open circuited and measure voltage across solar cell, no current flow through load and it is open circuited V_OC (open circuited voltage).

 

Circuit Diagram

Instruments / Equipment Required

• Solar cell / Solar panel
• DC milli ammeter
• Voltmeter
• Multimeter
• Patch cords
• Light source

Download IV Characteristcis of Solar Cell

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 I_SC = _____________

Open circuit condition

• Make the ammeter circuit open circuited and measure voltage across solar cell
• It is open circuit voltage V_oc = ____________
• 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, V_oc and I_sc are the end point of the solar cell characteristics in x axis and y axis respectively. Note down the reading of V_m and I_m from the readings and show on the graph. The point corresponding to V_m and I_m 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, V_m = ______ V & I_m = _________ mA

Maximum useful power = V_m × I_m

Ideal Power = V_oc × I_sc = _________ mW

Fill Factor = (V_m × I_m) / (V_oc × I_sc)

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.

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