This is not exactly news. On the one hand, it's true; solar is considerably cheaper than anything else in large swathes of the developing world and has been for a while now. It's only going to get more-so. However, that's only the case if you use it to offset grid usage; a complete off-the-grid solar system, with enough storage to see you through the night and the odd cloudy day, is still going to cost you more over its life than the equivalent grid supply. The costs are heading down, and it's not far off being worth doing in some places, but it's not there yet. There are a few cases where supply costs aren't the only consideration where solar-with-storage is already reliable for other reasons; we came across a mining outfit with a very large crusher and a very unreliable grid. Every time the grid cut out, their crusher stopped, and someone had spend a couple of hours climbing through it clearing out the half-crushed rubble before they could restart it. Concerns about the 'unreliability' of renewables are a very first-world thing, where the grid alternative has several nines of reliability; when there are more sevens than nines involved in the grid reliability, renewables suddenly look pretty reliable.
But. On the other hand, the cost numbers are a bit deceptive. The comparison, especially in the first world, is always for _new build_ capacity. So if you're looking to add 100MW capacity and the choice is between solar-with-storage and a new 100MW coal plant, solar might well out-perform coal in a few years. But if the choice is between 100MW of existing coal capacity and 100MW of new-build solar-with-storage, there's no competition and won't be, probably ever, for two reasosn: One, you've already spent the sunk costs of the coal plant and they're being amortized over the remaining life of the plant, so replacing it with solar means there is a sudden 'cost' to account for, which you've actually already spent but which you were planning to make back in the years to come but now can't. And two, because almost all the costs of renewables are in the construction phase (ie there is no fuel to buy), you need the money sooner than you do with fossil fuels, so you don't get to spend the money on something else. As a crude example, suppose you have two 100MW projects, each with a life of 20 years, one coal and one solar. The coal plant costs $50 million to build and you'll spend $50 million on fuel evenly over its 20 year life, while the solar plant costs $100 million to build with no operating costs. The overall cost is equal, but with the coal plant you have $50 million to invest in something else until you actually need the coal, while with the solar plant you've already spent your whole $100 million.
The exact difference depends on the (assumed) discount rate, and what number to use is a matter of considerable controversy. See eg. the Stern review, which assumed a very low discount rate, to make spending now look more competitive than spending in the future. To go back to the example, assuming a discount rate of 3%, the solar project has to cost around $88 million to be competitive with the coal project.