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I've always been told that the equator is the region on Earth that receives the most sunlight.
But I wondered, since the ecliptic is the circular path that the Sun appears to follow over the course of a year, then wouldn't the ecliptic path receive more sunlight than the equator?
The ecliptic path, is a well defined trajectory when displayed on the background of the fix stars like in the following figure
(taken from physics.csbsju.edu)
However, there is not such thing as an ecliptic path on the surface of the Earth. If you thought of it as the "Ground track" of a satellite but applied for the Sun, you have to consider that the rotation of the Earth would make that "ground track" of the Sun look very different than the one on the figure above. It would be a spiral going around the Earth ~365 times at latitudes between the tropics of Cancer and Capricorn (remember that the Sun takes a full year to go trough the ecliptic path).
When the Sun is at its Northernmost declination (the top point of the red curve above), which is ~23° all the points on Earth at latitude ~23° North (the tropic of Cancer) will receive the maximum possible solar irradiation at the solar noon of that day. Once the Sun moves down to declination 22°, it will be the turn of the points at 22° North and so on.
The reason why the Equator is the line that receive the most solar radiation is because it is the one that is on average closer to the Sun's ground track (in other words, is the place with the maximum mean solar elevation).
An equivalent visualisation would be to take the mean of the ecliptic, and by looking at the above red line it is quite straightforward to see that it would be a flat line on the celestial equator, that translates to the Earth's equator.
Does that makes sense to you?
