What do you think animals run on? Gasoline? Plants are like batteries, storing solar energy. Animals, including humans, charge up by consuming these plants. And for those who don't eat plants, they eat charge up by eating the animals who charge up on the plants.
Fossil oil qualifies too, but the fact it's all ancient stored solar energy rather than solar energy captured now makes it vastly different. Oil produced by capturing solar power now should qualify as "solar power" just as much as photovoltaics.
You can consider the solar->plant->animal cycle to effectively be similar to using solar panels. Using solar panels directly would be inefficient without batteries anyways, so the solar->plant->animal cycle is directly analogous to how we would use solar panels.
Obviously our tissue is much well less adapted to so many hours of sunlight compared to plants. Also even plants only absorb a relatively small part of the light spectrum (none of the green light). Also even plants required compounds from the earth and the air to actually harvest the energy to store so it's a pretty complicated process to do in an actively moving human.
I don't see why you would expect animals to evolve a way to "capture sunlight" (though some do: http://umich.uloop.com/news/view.php/77109/4-incredible-phot...) when it's far more efficient from the standpoint of the animal to eat plant matter.