Is the sun the main source of energy on earth

What type of energy and in what context?

Technically the Big Bang is the main source of energy on earth. Technically the sun, and it's predecessors, are the source of energy on earth because without it there would be no earth and thus no energy. Without the sun would we still have energy? Yes and no. We have geothermal energy, hydro, nuclear, wind, and other sources that do not rely on the sun nor are derivative of the sun's energy. Life can live without the sun, we see it around the geothermal vents in the ocean floor. Life as you see it daily? No. We need the sun for that. We need the sun for solar energy. The sun was required for coal/oil energy.

So the absolute answer to the question "Is the sun the main source of energy on earth?" is, in my opinion, no. It is a biggy but not the main.

I have to disagree. Without solar radiation there would be no wind. Without solar fusion there would be no heavy elements to produce nuclear energy. Geothermal and Hydro energy are not directly attributable to the sun, but derive from the same coalescence that formed it.

Is the sun the only source of energy? No. The main source? I would say yes.