The core of the sun.
If you are asking where does solar nuclear fusion take place, then that would be at the core of stars.
The process generating solar energy is one of nuclear fusion.
Solar energy is formed by nuclear fusion in the sun
They seem independent to me - except that solar energy arises from nuclear fusion in the sun
well...
Sun
Solar neutrinos are electron neutrinos that are in the sun. The sun is what produces nuclear fusion.
From the nuclear fusion reaction in the sun
Nuclear fusion energy
It has to be at hundreds of millions of degrees kelvin, before a fusion reaction between deuterium and tritium will start
The ultimate source of solar radiation is nuclear fusion that occurs in the core of the sun. This process releases energy in the form of electromagnetic radiation, which includes sunlight.
That was whoever invented nuclear fusion, and it was before my time.