All natural energy in the universe comes from nuclear reactions
One subtle but significant misconception is that solar energy is not nuclear energy. The reality is quite different. All stars, including our Sun, produce their energy from fusing the nuclei of smaller atoms together to make the nuclei of larger atoms. Our Sun is a middle-aged star, so nearly all of the energy produced comes from the fusing of Hydrogen nuclei together and making Helium nuclei. Some Helium-Hydrogen fusion occurs, as well as Helium-Helium fusion, but both are but a very tiny fraction of the total fusions in our Sun.
H-3 + H-2 = He-4 + neutron
When fusion occurs, a minute fraction of the atomic masses of the two nuclei being fused is annihilated into pure energy, as demonstrated by Einstein’s famous formula E=MC². It actually takes some thousands of years for this energy to migrate out from the core of our sun to the surface and be released into space. More than 99% of the released energy from the Sun is a weak form of gamma radiation, or what we more commonly call sunlight. This makes all sunlight nothing less than nuclear by-product material. Solar energy is actually nuclear by-product energy.
Wind energy is formed by the uneven heating of our atmosphere by solar radiation. Thus, wind energy may be correctly understood to be an indirect result of solar nuclear by-product material. In fact, all weather on our planet owes it’s existence to solar nuclear by-product material. Even fossil fuels can be understood as solar nuclear by-product material which has been stored for millions of years in decay-transformed plant chemistry (coal and oil). Literally, all forms of energy we have at our disposal are the result of the energy made in the natural nuclear reactions of our Sun.