Solar energy, in the sense of the sun providing light and heat, has existed for billions of years.

Here's a breakdown:

* Sun's formation: The sun formed around 4.6 billion years ago.

* Life on Earth: The first signs of life on Earth appeared around 3.8 billion years ago.

* Harnessing solar energy: Humans have been using solar energy in some form for centuries, like drying food and using solar ovens. However, the use of solar panels for electricity generation only began in the 20th century.

So, while the sun itself and its energy have existed for billions of years, humans have only been actively harnessing it for electricity for a relatively short time.