Imagine a large dish or fresnel lens suspended above the ground. Attached to that at the focal point is a solar cell. The unit is suspended from a cable and the necessary electrical wiring through a rotary coupler to prevent tangling. The dish or fresnel lens is lightweight; perhaps made of sturdy foam
covered in reflective material.
On the ground below the unit is a cow or goat. The solar collector and animal are connected by spring and tension line, so that a dimensional line drawn from the animal through the unit extends toward the sun, maximizing the collector's ability to generate power.
Because the proper location of the animal is always the center of the shady spot (the shadow of the unit itself), the more precisely the chosen animal hates sunlight, the better this will work. You may need to starve and/or overheat the animal(s) for it to work best, so they surely move to the shade. Maybe it's a shaved ostrich or something. They don't like being sunburnt.
Any recommendations on the right kind of animal? Are there any insect colonies or massive algae which could be used?