MARIA ELENA, Chile

On the solar farms of the Atacama Desert, the workers dress like astronauts. They wear bodysuits and wraparound sunglasses, with thick canvas headscarves to shield them from the radiation.

The sun is so intense and the air so dry that seemingly nothing survives. Across vast, rocky wastes blanched of color, there are no cactuses or other visible signs of life. It’s Mars, with better cellphone reception.

It is also the world’s best place to produce solar energy, with the most potent sun power on the planet.

So powerful, in fact, that something extraordinary happened last year when the Chilean government invited utility companies to bid on public contracts. Solar producers dominated the auction, offering to supply electricity at about half the cost of coal-fired plants.

It wasn’t because of a government subsidy for alternative energy. In Chile and a growing list of nations, the price of solar energy has fallen so much that it is increasingly beating out conventional sources of power. Industry experts and government regulators hail this moment as a turning point in the history of human electricity-making.

“This is the beginning of a trend that will only accelerate,” said Chilean Energy Minister Andrés Rebolledo. “We’re talking about an infinite fuel source.”