You have to read a bunch of news articles and keep an eye out for articles that actually include numbers. I don't know of any public databases aggregating that

You have to read a bunch of news articles and keep an eye out for articles that actually include numbers. I don't know of any public databases aggregating that sort of information. There are commercial services that sell data and reports. Keep in mind that solar electricity, like any form of electricity generation, has location-specific and project-specific cost factors. Building any form of power plant is cheaper in China than in Germany. Solar power prices in Nevada are almost always going to be cheaper than in Michigan, because even if the construction costs are the same, the arrays will get more sun per year in Nevada.