A study of the characteristics of a Solar Cell

EXPERIMENT NO. 12

AIM:- To study
i) illumination characteristics,
ii) current-voltage characteristics and
iii) power-load characteristics
of a solar cell.

APPARATUS :- a solar pannel, a voltmeter, a micro-ammeter, a decade restor box and a 100 W lamp fitted with an intensity control.

CIRCUIT DIAGRAM:-

PROCEDURE:-

ILLUMINATION CHARACTERISTICS :
1. The circuit is connected as per circuit diagram.
2. A 100 W lamp is arranged over the solar pannel such that light falls on it at normal. Initially, the intensity ( intensity is taken as proportional to the voltage given to lamp i.e. dimerstat voltage ) control is kept at its minimum and the lamp is switched on.
3. The voltage is switched off (zero) and the current is noted.
4. The intensity of the lamp is varied in steps and the current is noted at each setting. The readings are noted in Observation Table 1.

ii) CURRENT-VOLTAGE CHARACTERISTICS :
5. The intensity of the lamp is kept at minimum (I₁).
6. The voltage and current are switched on.
7. The load dial is set at 470 ohms. The voltage and current are noted down. The load is set to 1 k, 2.2 k, 3.3 k, 4.7 k and 10 k ohms and at each setting the voltage and current are recorded. The readings are recorded in Observation Table 2.
8. The intensity of the lamp is increased (I₂).At this setting, step 7 is repeated.
9. The intensity of the lamp is set to its maximum (I₃). At this setting step 7 is again repeated.

iii) POWER-LOAD CHARACTERISTICS :
10. Using the sets of reading in observation table 2, the output power (power = current x voltage) of the pannel is calculated. The values are recorded in Observation Table 3.

OBSERVATIONS:-

Observation Table 1 - Illumination characteristics (with voltage switched off and current switched on)

Intensity (Volts)	Current (micro-amps)
0 20 40 60 80 100 120 140

Observation Table 2 - V-I characteristics (with voltage and current switched on)

R_L (k ohms)	Intensity I₁ (0 Volts)		Intensity I₂ (100 Volts)		Intensity I₃ (130 Volts)
R_L (k ohms)	Voltage (Volts)	Current (micro-amps)	Voltage (Volts)	Current (micro-amps)	Voltage (Volts)	Current (micro-amps)
0.47 1 2.2 3.3 4.7 10

Observation Table 3 - P-R_L characteristics

R_L (k ohms)	Intensity I₁ (0 Volts)	Intensity I₂ (100 Volts)	Intensity I₃ (130 Volts)
R_L (k ohms)	Power (micro watts)	Power (micro watts)	Power (micro watts)
0.47 1 2.2 3.3 4.7 10

GRAPH:-

1. For ILLUMINATION CHARACTERISTICS, a graph is plotted between the current and intensity (intensity is taken as proportional to the voltage given to the lamp).
2. For V-I CHARACTERISTICS, a graph is plotted between the current and voltage.
3. For P-R_L CHARACTERISTICS, a graph is plotted between the power and load.

RESULT:-

1. When voltage across solar cell is switched off, the current is found to vary linearly with the intensity.
2. The maximum power output is found to be mW.
3. The optimum load is found to be k-ohms.

PRECAUTIONS:-

1. The terminals of the solar cell are to be correctly connected.