The 2nd and 3rd 100GW of solarI've been thinking about the fact that by the end of 2012 the world solar industry will have installed ~100GW [I get that by adding: ~30GW in 2012, ~27GW in 2011, ~17GW in 2010, and ~26GW 2000-2009.]
The cost for the first 100GW of solar will be ~$450B or $4.5/W: ~$200B for the panels and ~$250B for the installation (+ everything else).
The world should install the next 100GW by 12/31/15 at a cost of ~$250B or $2.5/W: ~$80B for the panels and ~$170B install (+ ee).
The 3rd 100GW should be installed by 12/31/17, and cost no more than $200B or $2/W: $65B for panels and $135B for install (+ee).
Given the recent past I may be overestimating the future costs by 10%. Still, the next 200GW of installed solar will cost no more than the first 100GW.
In particular I may be greatly overestimating the install costs. About 85% of the first 100GW are/were installed in developed economies (those with the highest labor costs). With the continuing reductions in installed cost of solar, developing countries will "host" a growing proportion of the 2nd and 3rd 100GW, where installed costs will be lower simply because of lower labor costs. Example: it is believed that the installed cost of solar in China is already lower than in Germany (which has been the lowest cost market the past several years).
Plus the panels in the second 100GW will be ~2% more efficient than the first, and the third 100GW will be another 1% more efficient than the second. (new panels get about 0.5% more efficient/yr) Assume the first 100GW was 14% efficient, if the second is 16% efficient, and the third is 17% efficient, then based on efficiency alone the second will require almost 15% fewer panels than the first (and hence less labor, fewer connections etc.) and the third will require 6% fewer panels than the second.
[Somewhat off topic, if the first 300GW costs ~$900B as I estimate above and the next 600GW costs no more than the first 300GW (an intuitive leap based on my analysis above), the average cost of that next 600GW will be approximately $1.5/W installed.]