Solar companies are overselling their growth potential

I would say that at this point in the cycle, many solar companies are overselling their growth potential. The key thing to remember is that this case is fundamentally different from a PC. A PC could be scaled up almost arbitrarily, with economies of scale paying big performance, and hence financial, returns. ("Moore's Law" is just one consequence of this scalability.) This fact made the investment in successive generations of costly technology worthwhile. A photovoltaic cell is fundamentally incapable of providing more energy than the light incident upon it, and is more practically limited by the Schockley-Quiesser limit (~33% for single-junction cells). Thus the best technology improvement that can be hoped for is one asymptotically approaching this limit - a case in which there is diminishing, rather than enhanced, returns. "Moore's Law"-type returns for solar cells are therefore, sadly, a myth, independent of the system-level approach employed.

Because of this, a lot of what the industry is now pitching is largely hype, either intentionally generated by marketing folks, or unintentionally created through fundamental misunderstanding of the physics involved. Either way, it isn't a pretty sight.

Shocmley-Queisser or not, unlike in the case of computer chips, there is a inviolable ceiling to solar cell efficiency (100%), and it is only one order of magnitude from where we are now with off-the shelf, easily available mass produced panels. The cost of the silicone part can keep going down, but the panels cannot get smaller, so the glass and aluminum costs also set a basement for the panel costs, also no more than one order of magnitude away.

Ultimately, the cost of panels is not really the hurdle to Solar development: The real hurdle is getting financing, permits and PPAs, which are political and financial issues rather than technical ones.

That is what sets successful solar developers apart from road kill. The companies that can position themselves for the next break in any of those arenas, lay-in enough capacity to take advantage, and survive long enough to see the changes will be the real victors.