Bogus numbers: Wind and solar are always portrayed using "nameplate" capacity; their full theoretical capacity under ideal conditions, which rarely happens. (They generally have no control over this, either.) On the other hand, something like a natural gas plant can usually produce at its full capacity pretty much on demand, although it probably only does this on relatively rare occasions, too.

To use a local example, I have a solar plant nearby which is rated at one megawatt "nameplate". But for whatever reasons it is currently maxing out at only 60% of that, even under ideal conditions. And it looks like its average output may be as low as 17%, depending on how you count things. (I generally use 25% as a round, ballpark figure for wind and solar, although it looks like off-shore wind power at least is generally running much higher than that.)

Wishful thinking: The wind and solar folks like to pretend that with enough storage (battery, pumped hydro, and so on ) then these can be as reliable and productive as more traditional power sources. Except that the storage stuff only has limited capacity, and is remarkably limited in many cases (to hours of capacity if not just minutes), so they're going to need something much more robust for backup. And that's generally means that the traditional sources will still be needed to fulfill this role. Which may be mostly fine technologically, but economically it will be quite expensive, and you need to include that added expense in the overall costs for wind and solar. It is wishful thinking to just ignore these factors.

Google, which was quite into renewals themselves a while back, long ago stated that it was obvious that these were never really going to work out for them. Given that Google has pretty much unlimited intellectual and financial resources (or at least it did at the time), if there was anybody who could make this work it would probably be them. But apparently not so much.