Outdoor solar lighting uses the same process to generate power as the solar panels on your roof (or that you could install on your roof, if you chose to). Basically, it uses photovoltaic (PV) cells, which collect and convert solar energy into electricity.
The solar cells use semiconductors to absorb the sun’s light, which interacts with the silicon and other elements to create electricity. The electricity flows through wires which power the battery, which in turn powers the light.
This is an extremely simplified explanation, but it will give you the general idea of how solar cells work. They can only create electricity from direct sunlight, which is why solar lighting needs a battery in order to be able to light up the night.
In order for the batteries to retain a continuous charge, the solar light fixture must be in a location where it can receive sunlight for most of the day. If it only receives partial sun, because it’s blocked by trees or another building, or because your region has lots of cloudy weather, the batteries will run down sooner, and your fixture will provide light for a shorter amount of time.
Most outdoor solar lighting fixtures have a backup power system which uses rechargeable batteries
Solar lights which use a low amount of electricity often use small AA Ni-Cad or NiMh batteries. But more powerful solar lighting fixtures (like solar flood lights) use a sealed lead acid battery.
Light levels are automatically measured by photo sensors (like the kind that tells your camera when to use its flash) that are built into the solar light. They monitor the light intensity and turn the LEDs off at dawn and on at dusk. However, you do need to make sure there are no artificial light sources (like a street light or flood light) that may give a false reading and prevent the light from turning on.
Outdoor solar lighting usually uses LED bulbs
They use less power than incandescent bulbs and are much longer-lasting. Until recently, solar lighting overall has not been as bright as lighting powered directly by electricity. But the newest super bright LEDs can now illuminate as well as halogen bulbs.