If you have a yard and have ever thought about lighting it up at night, you've probably heard of solar garden lights. They are still quite expensive, but their advantage is that you don't have to run any wiring for them. As long as a location receives direct sunlight, you can place the lights there.

These lights are super interesting because they are almost like mini-satellites. They generate and store their own energy during the day and then release it at night. This is like a satellite that stores solar energy when it is on the sunny side of the planet and then uses that energy when it is on the dark side.