For years, the economic case for solar came with an awkward qualification. Yes, it had no fuel bill. Yes, its operating costs were low. And yes, over the life of a project it could already produce cheaper electricity than a new coal or gas plant. But first, someone had to pay for it. Solar concentrated most of its lifetime costs at the beginning. Fossil power appeared to ask for less capital upfront and spread the rest of the bill across decades of coal or gas purchases. In rich countries with deep capital markets, that distinction could be managed.…