I absolutely disagree with your point about it being unlikely to build 5 400 MW of solar capacity in france by 2020... We are in 2009 and have about 11 years to that date.

That would be 490 MV each year.

Global production of PV cells in 2007 was about 3800 MW

http://www.thaindian.com/newsportal/health/global-production-of-solar-ce...

In 2006 production was at 2 521 MW

I don't know the figure for 2008 but I expect it to be over 5000 MW.

There is one norwegian solar cell company that alone was producing silicon wafers in 2008 of in the range of 600 MW each year.

They have extensive plans to build more production capacity and estimate that they will produce close to 1800 MW/year of silicon wafers by 2010.

They currently sit on the most cost efficient production technology, but estimates that they in 2010 will cut production costs per watt by half of what was average industry cost in 2005.

They project their production costs for solar cells to be 1 euro per watt peak in 2012. You talk about the 6-7 dollar/watt market price of current solar systems.

So their estimated production costs will be much much lower than the current market price, wich will be a good thing since they expect there to be a supply glut and dramatic fall in prices of solar panels around that time wich will lead to failure of those solar cell manufacturers that can not produce as efficiently as they can.

Also the REC solar panels have higher conversion efficiency (12.4 - 14 %) than many other solar panels so you will not have to cover as much area. By using their best modules you only need to cover about 38 million sqare meters.Using their cheepest modules you would need to cover 43-44 million sqare meters. They are also working hard on improving conversion efficiency.

You cannot seriously claim that REC is not mass producing in cost efficient ways. You could argue that those who create polisilicon modules based with conversion efficiency closer to 20% are not as cost efficient.

By 2020 a lot of exiting new solar PV tecnology is expected to mature and we can hope to se panels with higher than 20% conversion efficiency produced at lower costs than traditional wafer based silicon solar cells.

You will get flexible thin film cells in all sorts of colours and levels of transparency for good building integration not only on roofs but on walls and windows. And you will get high efficiency concentrating (parabolic dishes) solar PV-systems using multijunction solar cells for use in desert PV-plants. (Currently multijunction cells have achieved over 40 % conversion efficency at high concentration and 31% efficiency under regular sunlight).

http://solar.asu.edu/multijunction.shtml

My conclusion:

France will easilly achieve a total of 5 400 MV of installed PV by 2020. It will not have to cover 54 million m2. If you go for desert like areas you can use consentrating PV wich has much higher conversion efficiencies. (30-40%) thus needing only a third or a fourth of the area suggested by Robert Rapier.

I would urge France do multiply their goal by a factor of ten and go for 54 000 MW instead of the puny 5 400 suggested in the plan.