Lesson 5 – L: Launch Your Learning: How Do Solar Cells Turn Light into Power?
L: Launch Your Learning
Measure a Solar Cell Under Different Light Conditions
Now you put the ideas to work. Working with a partner, you will connect a solar cell to a multimeter, then measure its voltage and current under several light conditions and calculate the power for each. Record everything in your data table — your measurements are your evidence.
What You Will Do
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Step |
What You Do |
What You Are Looking For |
|---|---|---|
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1. Connect for voltage |
Attach the solar cell to the meter leads as your kit directs; measure the open-circuit voltage in your first light condition and record it. |
A positive DC voltage in bright light. |
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2. Measure current with a load |
Connect a small load as directed, set the meter to read current, and record the value. |
A current reading in A or mA, with the right units. |
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3. Calculate power |
For each condition, compute P = V × I and record it in watts. |
A power value for each light condition. |
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4. Change the condition and repeat |
Change the light — move the lamp closer or farther, tilt the cell, or shade part of it — and measure again. |
How V, I, and P change as the condition changes. |
Your Solar Cell Data Table
You will fill in a table like this one. Record voltage and current for each condition, then calculate the power.
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Condition |
Voltage (V) |
Current (A or mA) |
Power (W = V × I) |
|---|---|---|---|
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Bright light / lamp close |
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Medium light |
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Low light / lamp farther |
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Partial shading |
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Pause and Think
After your first two conditions: which changed more when the light got weaker — the voltage or the current? What does that tell you about why the power changed?
From Your Data to a Real Mini-Grid Decision
A single measurement is a start, but engineers reason about a whole system across a whole day. Use your data to see the pattern: which condition produced the most power, and how power fell as light weakened, the cell tilted away, or part of it was shaded.
Turn that pattern into a claim you can defend. Write one or two “If…, then…” statements straight from your numbers — for example, “If the panel is shaded by half, then power drops from ___ W to ___ W.” A claim backed by your own measurements is evidence, not just an opinion.
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Question to Analyze |
What to Look For In Your Data |
|---|---|
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Highest power |
Which light condition gave the most power? Why might that be? |
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Effect of weaker light |
How did power change as light got weaker or the cell tilted away? |
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Effect of shading |
How much did partial shading lower the power compared with full light? |
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Real-world limit |
What times of day or weather would limit a community’s solar power? |
Key Idea
A solar cell’s output depends on sunlight conditions — brightness, angle, and shading. Because that output varies, engineers must design solar systems to account for it, rather than assuming the panels always deliver their best.
Explain With Evidence
A school mini-grid runs on a small solar array and a battery. On sunny days the panels power lights and phone charging; on cloudy days they make only about half as much. Based on your data, what could engineers or staff do to keep enough energy on cloudy days — and what trade-off does your idea accept?
