Inside a Solar Yard Light

You can see the battery, LED and controller board. If you cover the light sensor, the LED turns on, like this:

Inside a solar yard light turned on

Here are close-ups of the LED and the controller board:

LED and circuit board inside a solar yard light

LED and circuit board inside a solar yard light

On the other side of this module is a four-cell solar array, measuring 2 inches by 2 inches (5 cm x 5 cm), and the photoresistor:

Solar yard light solar array

Here is a closer view of the photoresistor:

Solar yard light photoresistor

See How do the streetlights turn on automatically at night? for more information on how photoresistors work.

Now let's see how the whole setup works to light your yard at night.