While the concept of using sunlight to generate electricity dates back to the 19th century, the invention of the practical solar panel is typically credited to 1954.

Here's a breakdown:

* 1839: Alexandre Edmond Becquerel observed the photovoltaic effect, the phenomenon where light converts to electricity in certain materials.

* 1954: Bell Laboratories created the first practical silicon solar cell, which achieved a 6% efficiency in converting sunlight into electricity.

Therefore, while the photovoltaic effect was discovered in 1839, the invention of the solar panel as we know it today happened in 1954.