you do not include support system (mostly distribution) associated costs
This will triple the cost of buildout for the renewables ABOVE the costs show above if a 24-hour production cycle is needed, otherwise you are doing your work with coal.
We do not yet have the storage capacity at a reasonable cost - these projections are for 2020 with an assumption of much cheaper batteries than today.
I'm starting a new comment here because this is a different topic - the cost of powering a grid, reliability, 24/365. The previous comment was about the cost of electricity as it comes from the plant/farm.
You are correct and incorrect about storage at a reasonable cost. We are starting to install batteries for short term storage (daily cycle) and we have already built a lot of pump-up hydro storage (PuHS) which we needed in order to incorporate nuclear on our last-century grid.
PuHS is not cheap. Estimates for new PuHS run from 9c/kWh to 23c/kWh. The 9c number was given by DOE Secretary Chu.
But let's leave storage aside for the while. What makes most sense to fill in for wind/solar and nuclear is natural gas. The plants have a low installed cost and are highly dispatchable, meaning they can be turned on and off quickly unlike coal.
How about some installed cost comparisons?
Wind Onshore
$1.64 Installed Cost/Watt
DOE 2014 Wind Technologies Market Report
PV Solar
$1.43 Installed Cost/Watt
Greentech Media 3rd Qtr 2015 Executive Summary
CCNG
$1.09 Installed Cost/Watt
Open EI DOE Database Median Overnight Cost
Nuclear
$8.33 Installed Cost/Watt
Vogtle LCOE adjusted for additional budget overruns.
Wind and solar tend to produce at different times of day. A watt of wind plus a watt of solar is likely to produce, on average, 80% of the time with the rest filled in by a watt of NG. Cost to install a watt of all three = $4.20
Nuclear plants, once dialed in, produce about 90% of the time but we'd still need a watt of NG to fill in the other 10%. A watt of nuclear plus a watt of CCNG = $9.40.
The cost of supply the grid with a 'reliable' watt of renewables + NG is 40% the cost of supplying that watt with nuclear + NG.