First of all, let me make it clear that this article is about “utility-scale” solar power, not rooftop solar power. Rooftop solar is a different beast, because it’s more expensive per unit of electricity than utility-scale solar but it generally competes with retail electricity prices rather than wholesale electricity prices. For millions of Americans, and many more worldwide, rooftop solar is already cheaper than electricity from the grid, but until recently, utility-scale solar projects weren’t cheaper than other types of power plants (ignoring externalities, which we shouldn’t really do but we do). That has been changing.
As you can see in the chart at the top, the levelized cost of electricity from solar power is expected to be as low as $60/MWh, lower than the lows for any fossil fuels or nuclear power. And that assumes a 20-year lifespan for the solar power plant, much less than (maybe not even 50% of) the actual lifespan of a solar power plant.