"Free fall" is the motion of an object when gravity is the ONLY force acting on it.
In true 'free fall' the speed of an object increases at a constant rate for the total duration of the fall. The rate of increase, on or near the Earth's surface, is 9.8 meters per second for each second of fall.
True free fall is almost impossible to observe in everyday life, because whenever we see anything falling, it's almost always falling through air, so gravity is NOT the only force acting on it. The friction due to the motion through air works against the gravitational force. In many cases, the result is that the object's speed eventually stops increasing and becomes constant, at a speed often described with the faux technical, high-fallutin' sounding phrase "terminal velocity". It must be understood that 'terminal velocity' is NOT a property of gravity or of free fall, but is only a result of falling through some surrounding stuff that interferes with the process of true 'free fall'.
An objects falling speed will increase until it is at what is called terminal velocity, meaning it can't go any faster, it will stay at the same speed, until it hits the ground.
I think that the solar panel would work under a fluorescent or halogen light if the photons are being produced. These types of lights mimic sunlight so it would not work as good as the real thing but it could work. Just not be as powerful.