The US Federal Energy Regulatory Commission (FERC) is usually first with information on newly installed generation capacity. But first doesn't always mean correct.
Since FERC published their data both the American Wind Energy Association and also the Solar Energy Industries Association/GTM Research have published year-end wind and solar numbers. Both are significantly higher than FERC's estimate. In fact solar was so much more that it pushed natural gas out of second place and, for the first time ever, was the second largest form of new generation capacity additions in the US.
Of course there are no guarantees that the gas industry will not come along with some more last minute additions to gas capacity. Nonetheless it is pretty amazing that, albeit according to not-yet-finalized data, solar was the second largest form of new generation capacity additions in the US. It's particularly impressive when you consider that solar has come from practically nothing in 10 short years;