Relevant bits:

> “On their face, they’re less than a third the price of building a new coal or natural gas power plant,” Ramez Naam, an energy expert and lecturer at Singularity University, told Earther in an email. “In fact, building these plants is cheaper than just operating an existing coal or natural gas plant.”

> There’s a 30 percent federal investment tax credit for solar projects that helps drive down the cost of this and other solar projects. But Naam said even if you take away that credit, “these bids, un-subsidized, are still cheaper than any new coal or gas plants, and possibly cheaper than operating existing plants.”

(emphasis mine)