A common belief is that solar panels became cheap because of low-cost Chinese labor and lax Chinese regulation. This article argues that it's mostly an issue of scale of production.

"A study of the photovoltaic industries in the US and China shows that China's dominance in solar panel manufacturing is not driven solely by cheaper labor and government support, but by larger-scale manufacturing and resulting supply-chain benefits."

I think in a few years, as solar prices continue to decline, and so does the solid state equipment that ties you into grid, solar panels will eventually become standard equipment on most buildings, just like electrical lights are right now.