Solar cells (photovoltaic cells) are used as power sources in:
electronic devices such as calculators,
robotics,
solar power stations,
spacecraft and space stations,
street lights or warning lights.
Solar cells convert solar energy (light energy) into electrical energy.
Photocells are used as relay switches and light detectors:
in burglar alarm systems,
to calculate runners’ speed,
to count the number of vehicles passing by a checkpoint,
at the automatic doors in commercial buildings.
When the intensity of light falling on the photocells is uneven or fluctuates, the current in the photocell circuit will also fluctuate. These fluctuations are utilised in:
Image sensors in chargecoupled device (CCD) for digital imaging. Light of different intensities are converted into electrical signals of different strengths.
Photomultipliers in night vision devices to detect faint light.
Photoelectron spectroscopy used in medicine and particle physics.