Answer : Electromagnetic energy
Explanation :
The solar panel usually combines multiple photo voltaic cells. Electromagnetic energy is used to power a solar panel. As the electromagnetic energy or rather radiations from the sun reaches to Earth in the form of radiation which is then collected by these photo voltaic cells. As the term solar energy simply suggests that the energy is coming from the sun. Thus, electromagnetic energy coming from the sun was produced when electric charges inside the sun change their potential energy.