There are a number of alternatives here but the simplest is an ldr light dependant resistor.
How solar panels track the sun.
Scientists use sunspots to track solar cycle progress.
Solar cycle 25 is underway and scientists are eager for another chance to put their understanding of solar cycle signs to the test.
The principle on which these work is that their resistance decreases as the light intensity increases.
Nasa scientists study the solar cycle so we can better predict solar activity.
Scientists use several indicators to track solar cycle progress.
Sunspot number over the past five solar cycles.
Understanding the sun s behavior is an important part of life in our solar system.
Since we want to be able to track the sun we need some form of light detector.