This Solar Powered Outdoor Wall Light is the ultimate in simplicity. Just screw it to an outdoor location where it can be charged by sunlight (ideally facing south) and press the button to enable it. No wiring or batteries required!
When it becomes dark outside it will be triggered by motion from within about 3 meters distance, and turn on its bright 4000K LED light. If the motion continues, the light stays on, otherwise it shuts off automatically after 30 seconds.
If there is sufficient sunlight reaching its solar panel during the day, it should generate enough charge to be motion-triggered all night long. (Assuming there isn’t an unusual amount of motion nearby making it trigger constantly!)