If you need to build a gas power plant to compensate for the production solar and wind can't give when you need it, the price per watt of electricity
explodes.
Picture this: It's 9PM on a cold winter day, sun has been down for hours and there was not been a lot of wind today. People are home, watching TV and heating their home. Batteries are now empty (they started depleting at around 5Pm when the sun went out). You now need to produce 100% of the peak electricity consumption of the year, using gas, oil, coal, nuclear or hydro.
This scenario shows that whatever you do with wind and solar, you need to be able to produce 100% of the peak electricity consumption with controllable power plants. The cost of wind and solar is not the cost of the power plants vs the cost of the gas power plant it replaces, but on top of it. For every GW of wind you add to the grid, you need to add an equivalent GW from a controllable source just in case. This backup GW won't be used most of the time, but the cost of it should be taken into account when you compute price per GW.
It is unfair to compare the price per GW between solar/wind and gas/nuclear/coal/hydro, when the feature of both are so different. Solar and wind provide amazing ROI, when they want to, not when you need it to. So the cost needs to include the price of the backup system that's going to stay dormant 80% of the time. Ans that significantly change the math of it all.
The only way to get out of this is to either reduce our total energy consumption, so that the current controllable plants can provide enough, and then build solar and wind, to reduce how often we need to rely on them. Or to find a green and controllable energy source, like hydro (which has other issues).