No they're not, I've told you the costs. To reiterate on just one area: silicon prices have declined from $450/kg to $100/kg in just 1 year, they are now a quarter of what they were in 2008. Low cost thin-film technologies have already been developed many of which use less silicon than before and some of which utilise just 5 microns of silicon instead of the hitherto 200 microns, 40 times less silicon. On top of that non-imaging optics has been brought to bear to create cheap plastic and dye composite concentrators which have achieved 20% efficiency in the
lab. These concentrators, concentrating light at the sides of a plastic sheet rather than across its full face area, require up to 100 times less silicon to be covered to achieve the same job.
The 2 greatest economic problems with solar are cost of silicon and cost of installation. On the cost of silicon side, the three savings outlined above when applied to the same panel equal 1/4 x 1/40 x 1/100 = one sixteen-thousandth of what was previously required, or 1/16000. The cost of silicon will no longer be an issue as these advances are commercialised.
On the installtion side, which costs two-thirds of the price of a solar system, the way that will be overcome on a large scale is through creating sheets that can be self-installed. Flexible sheets of solar cells are already being made. With widespread adoption expertise will also become widely available just as mechanics are widespread and installation will become cheaper and far faster.