If we take a look at Sharp Solar with revenues of $1.5 billion last year and a 27 % market share, we can extrapolate a total market of $5.6 billion in photovoltaics for 2005. If you transform that from dollars to barrels of oil ($70/bbl) it's 80 million bbls. In other words, the solar industry has roughly the same value of a single day of world oil production. Solar power is a pretty dainty industry at the moment.
The solar cell production grew at 34 % in 2005 and 32 % in 2004 according to SolarBuzz. The annualized rate of growth in photovoltaics production has been 27 % over the past fifteen years (that's a doubling time of 2.56 years). All this growth is coming with tremendous pressure on silicon feedstock as noted by Sass Peress.
If photovoltaics keep growing at a 27 % annualized rate they'll exceed the world's annual oil revenue of today by 2028 (ignoring inflation).