Vernier Software and Technology
Vernier Software & Technology

Effect of Load on Solar Panel Output

Figure from experiment 18A from Renewable Energy with Vernier


Every power source has a characteristic internal resistance based on the materials out of which it is made and the physics of its operation. For example, a modern rechargeable AA battery generally has an internal resistance between 0.01 Ω and 0.10 Ω and a small generator such as those used for classroom wind energy experiments may have an internal resistance between 10 Ω and 100 Ω.

Solar panels, which operate in a very different way from either batteries or generators, have an internal resistance that depends on several variables, including temperature and the amount of light incident on the solar panel. In other words, the internal resistance of a solar panel it is not a fixed value; it fluctuates.

In general, the load and the internal resistance should be matched for optimal power output. However, in most cases it is not possible or cost-effective to vary the load according to changes in the internal resistance of a solar panel. Instead, engineers will choose a single resistance that is useful for the majority of the specified operating conditions.

In this experiment, you will vary the load resistance in a circuit connected to a small solar panel and graph the power output vs. resistance to determine the optimal load for your solar panel under your testing conditions.


  • Use the Energy Sensor to determine current, potential (voltage), resistance, and power.
  • Determine how solar panel power output varies depending on the resistance (load) in a circuit for a given light source.

Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

Option 1

Option 2

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Renewable Energy with Vernier

See other experiments from the lab book.

1Renewable Energy: Why is it So Important?
2What is Energy?
3Project: Energy Audit
4Voltage and Circuits
5Current and Resistors
6Mechanical Power
8Exploring Wind Turbines
9Effect of Load on Wind Turbine Output
10Blade Variables and Power Output
12Turbine Efficiency
13Power Curves
14Power and Energy
15Project: Maximum Energy Output
16Project: Build a Wind Farm
17Exploring Solar Panels
18AEffect of Load on Solar Panel Output
18BFill Factor and IV Curve of a Solar Panel
19Variables Affecting Solar Panel Output
20Effect of Temperature on Solar Panel Output
21Project: Build a Solar Charger
22Exploring Passive Solar Heating
23Variables Affecting Passive Solar Heating
24Exploring Solar Collectors
25Variables Affecting Solar Collectors
26Project: Solar Cooker

Experiment 18A from Renewable Energy with Vernier Lab Book

<i>Renewable Energy with Vernier</i> book cover

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