Project overview
This project builds a small model house with a photovoltaic (PV) panel that converts light into low-voltage direct current (DC) to power a miniature load (an LED, buzzer, or small DC motor). You can use it as an engineering demonstration (showing how a PV-powered device works) or as a focused science investigation (testing how one factor—like panel angle or shading—affects electrical output or device performance).
Safety (read first)
Adult supervision is required for cutting, drilling, soldering, using power tools, and working with batteries or lamps. Low-voltage panels reduce some risks, but other hazards remain: sharp edges, hot glue guns, rotating motors, and electrical mistakes. Use eye protection when cutting or drilling, keep hair and loose clothing clear of motors, and follow all manufacturer instructions for panels, motors, batteries, lamps, and multimeters. Check your fair’s rules before testing or displaying electrical devices.
Choose a research question
Pick one clear question. Here are good options:
- Recommended beginner question: Which panel angle produces the most electrical power?
- Shading test: How does partial shading of the panel affect voltage, current, or motor speed?
- Distance test: How does distance from a fixed lamp affect panel output?
Choose only one primary independent variable so your experiment stays focused and repeatable.
Brief background: how PV works
A PV cell is a semiconductor device that converts light into electricity. Photons in light transfer energy to electrons in the semiconductor, creating a flow of electrons—electric current. Several cells joined together form a small solar panel (PV module). A panel produces DC electricity while it is illuminated; it does not store energy (batteries or capacitors store energy). Useful electrical output depends on light intensity and spectrum, panel angle, shading, temperature, and the connected load.
Materials
- Small educational PV panel or PV module (rated for low-voltage DC)
- Load: low-voltage LED, buzzer, or small DC motor (match the panel’s voltage/current)
- Model-house materials (cardboard, foam board, or lightweight wood) and glue/tape
- Wires and safe connectors (alligator clips or screw terminals)
- Ruler or protractor and a simple adjustable mount or hinge for the panel
- Multimeter (for voltage and current measurements) — adult supervision required
- Optional: light meter or smartphone light-sensor app, thermometer, data sheets
Build the model
- Construct a small house shell that can sit under or next to the PV panel. Keep decorative work optional—focus on functionality.
- Mount the PV panel so it gets unobstructed light and so you can easily change its angle. A simple hinge and protractor mark work well.
- Route wires safely through the structure. Connect the panel to the load only after checking polarity and ratings.
- Leave access to wiring for inspection and testing; do not hide exposed connections.
Experimental procedure
Define variables before testing:
- Independent variable: what you change (e.g., panel angle).
- Dependent variable: what you measure (voltage, current, power, or motor speed).
- Controlled variables: things you keep the same (same panel, same load, same light source, same distance/time of measurement).
Example: Angle test
- Set the light source. Prefer sunlight outdoors. If using an indoor lamp, use a bright, manufacturer-rated lamp and note that indoor light is usually weaker and spectrally different from sunlight.
- Choose angles to test (for example 0°, 30°, 60°, 90° relative to the light source). Use the protractor to set each position.
- At each angle, measure open-circuit voltage and operating current under load with a multimeter (adult help required). When you measure voltage and current for the same condition, calculate electrical power as P = V × I.
- Repeat each angle at least three times and record results. Keep measurement time consistent (for example, measure 30 seconds after adjusting angle).
Data analysis and presentation
- Average repeated trials and calculate power where you have both voltage and current.
- Graph your dependent variable (e.g., power) versus the independent variable (e.g., angle).
- Discuss trends, sources of error, and limitations: light variability, measurement accuracy, temperature effects, and how indoor lamps differ from sunlight.
- Include hypothesis, method, variables, data table, graph, conclusion, and suggestions for follow-up tests on your display board.
Troubleshooting
- Panel seems to produce too little power: check light intensity, lamp suitability, and distance. Try direct bright sunlight for comparison.
- No output: check wiring, connectors, and that the load rating matches the panel. Confirm polarity.
- Motor won’t start: many motors need a high startup current. Try a lighter load (an LED) or a motor with a lower startup demand.
- Partial shading affects output more than expected: document the shaded area and test intentionally to quantify the effect.
Final tips
Keep decorations secondary to the science. A clear research question, careful measurements, repeated trials, and thoughtful analysis make a stronger project than an elaborate model alone. Always list your materials, explain your methods, and be ready to describe what the PV panel actually does: convert light to DC electricity while illuminated—not store power by itself.
