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Science and Technology K–6 · Year 6

Solar cell angle test: light energy into electrical energy

Science understanding: Physical sciences

Practical, model not builtLow risk

This site has no interactive model of its own. Where a step or a material names a Concept Studio model, simulation or tool, it has not been built; an external simulation a step names (for example PhET) is not part of this site.

The idea

A solar cell transforms light energy into electrical energy, and the current it delivers depends on how directly the sunlight strikes it, which is why rooftop panels are tilted toward the Sun.

What you need

  • a small solar panel rated about 2 V and 100 mA, with leads
  • a digital multimeter on the 200 mA dc current range (a panel rated 200 mA can push more than 200 mA through the meter when connected directly across it, which blows the 200 mA range's fuse, so use the 10 A range for such a panel)
  • a small 1.5 to 3 V dc motor with a paper propeller
  • the panel taped to a board hinged to a base, with a large protractor at the hinge
  • a pencil stood upright on the panel with plasticine, as a Sun pointer
  • a clear sunny day, between 11 am and 1 pm

How to do it

  1. Connect the meter directly across the panel on a current range. The current, not the voltage, follows the amount of light.
  2. Turn and tilt the panel until the pencil's shadow disappears: the panel now faces the Sun (angle 0 degrees). Record the current three times.
  3. Tilt the panel away from the Sun in 15 degree steps to 90 degrees (edge-on), recording the current three times at each angle.
  4. Graph the mean current against angle, and on the same axes plot the current the live model predicts at each angle from your first reading.
  5. Swap the meter for the motor and compare the propeller's speed at 0 degrees and 60 degrees.
  6. Explain which way a rooftop panel in your town should face and why.

What you should see

The current is greatest facing the Sun and falls as the panel tilts away, following current = I0 x cos(angle): a panel giving 100 mA facing the Sun gives 86.6 mA at 30 degrees, 70.7 at 45, 50.0 at 60 and 25.9 at 75. Beyond about 60 degrees real readings fall a little faster than the model because more light reflects off the panel's surface at glancing angles, and at 90 degrees the reading is small but not zero because light from the blue sky still reaches the panel. The voltage hardly changes over the same range, which is why current is measured. The propeller spins fast at 0 degrees and slowly or not at all at 60 degrees. A fixed panel in Sydney faces north; tilted at 33.9 degrees (the latitude) it faces the noon Sun directly at the equinoxes.

What changes

What you change
angle between the Sun's direction and the panel's face
What you measure
current from the panel
What you keep the same
  • same panel and meter
  • clear sky within the same hour
  • panel clean
  • meter on the same range

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

  • A solar panel works on heat, so a hot cloudy day is as good as a cool sunny one.
  • The voltage shows how much light the panel receives.
  • A panel works equally well at any angle as long as it is in the sun.

Safety card

Low riskLearners carry it out

Hazards

  • looking at the Sun
  • sun exposure

Controls

  • aim with the pencil's shadow, never by looking at the Sun
  • hats, sunscreen and shade breaks

Note

Risk assessment before the lesson using Primary RiskAssess or the school's own template.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

  • Science and Technology K-6 Syllabus (2017), current, taught until 2026; code read from the syllabus document on 22 September 2026ST3-8PW-STST3-1WS-S
  • Science and Technology K-6 Syllabus (2024), implemented from 2027; NESA's timeline is 2026 plan and prepare and 2027 start teaching, and schools may choose to implement it during 2026; code read from the outcomes page on 22 September 2026ST3-SCI-01ST3-PQU-01ST3-DAT-01
  • Australian Curriculum v9AC9S6U03AC9S6U02AC9S6H02AC9S6I02AC9S6I03AC9S6I04

Sources

The pages the author read to write this activity.

  1. www.scootle.edu.au/ec/search?accContentId=AC9S6U03
  2. curriculum.nsw.edu.au/learning-areas/science/science-and-technology-k-6-2024/outcomes
  3. www.nsw.gov.au/education-and-training/nesa/curriculum/science/science-and-technology-k-6-2017
  4. primaryconnections.org.au/teaching-sequences/year-6/circuit-breakers
  5. primaryconnections.org.au/v84-sequences/earths-place-space

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