Solar Power

Have you noticed the solar powered traffic signs near our college?

How do solar panels work?

Solar cells also called photovoltaic (PV) cellsphoto meaning "light”

voltaic meaning “electricity”

Sunlight is converted into electricity.

How can we measure the effect of light on a solar cell?

Solar Cells

QUESTION

Does the voltage and current delivered by a solar cell increase as the intensity of light

shining on the solar cell increases?

What to know before investigating this question

• solar cells ONLY one panel will be used

• Voltage = what is this?• current = what is this• Light intensity = how can we measure this?

Light Intensity

Use a Lux meter to measure

the light intensity.

The intensity of light is a measure of its brightness

How can you change the intensity of light?

Materials

• STELR solar cell panel• Digital multimeter• 2 STELR light sources• Power pack• Connecting cables with ‘piggy-back’ banana plugs• Light intensity (lux) meter• Mirrors

Part 1 - Step 1: PREDICT

• What do you expect to happen to the voltage delivered by the solar cell as the intensity of

the light shining on it increases.

Why do you think this will happen? Record your prediction and your reasoning on

the result sheet.

Step 2-8 Connect

• Step 2 Connect the two lights to the power supply, but do not turn them on yet.

• Step 3 Connect a black cable between the COM socket on the multimeter and the black socket of the number 1 cell on the solar panel.

• Step 4 Connect a red cable between the V/Ω socket on the multimeter and the red socket of the number 1 cell on the solar panel. Turn the dial of the multimeter to 2 on the V scale. This scale reads up to 2 V DC.

• Step 5 Have your light intensity meter ready to measure the light intensity. Turn on the lights and direct them at the number 1 cell. Record the voltage produced and the intensity of the light shining on number 1 cell in Table 1 of your results sheet, or in a spreadsheet.

• Step 6 Now change the intensity of the light shining on the solar cell. Record the voltage produced and the intensity of the light.

• Step 7 Continue changing the light intensity until you have at least six different sets of data. If possible your set of measurements should include placing the solar cell in direct sunlight.

• Step 8 Once you have at least six sets of data, turn off the lights, the multimeter and the lux meter.

PART 2- Step 1: PREDICT

What do you expect to happen to the current flowing in the circuit as the intensity of thelight shining on the solar cell increases.

Why do you think this will happen?

Record your prediction and reasoning on the result sheet.

Step 2-4: CONNECT• Step 2 Set up the circuit so that the multimeter measures the

current produced by cell number 1. Make any necessary adjustments to the multimeter to measure current instead of voltage. First allow for the fact that the current you measure may be large.

• Step 3 Have your teacher check your circuit, then turn on the lights and measure both the current and the intensity of the light shining on the number 1 cell. Record your result in Table 2 of your results sheet.

• Step 4 Now repeat steps 6–8 for inquiry question 1. Once you have at least six sets of data, turn off the lights, the multimeter and the lux meter and pack up according to your teacher’s directions.

Your Job

• 1 Record all of your results in the results tables

• 2 Use the data for Inquiry Question 1 to draw the graph of voltage against light intensity on graph

• 3 Use the data for Inquiry Question 2 to produce a similar graph of current against light intensity.

Did your graphs support your predictions?