This laboratory practice is intended for undergraduate students of chemistry, physics, biology, and engineering, to illustrate the simple concepts behind dye-sensitized solar cells (DSSCs), and how basic chemistry can be translated into a practical application through the use of microcontrollers. Unlike commercial counterparts, one of the main problems of handmade solar cells is their low efficiency that impedes their use as a power source, making the laboratory practice less appealing to students. In this work, we present a simple alternative application using an open-source microcontroller and a solar cell as a switch to turn the light on and off, depending on the actual lighting conditions in the room.