Here’s are some back of the hand projections I worked up this afternoon. If my facts are wrong, please insert your own and lets recalculate the projections. These are simply projections based on past trends. I didn’t take into consideration better manufacturing methods beyond current thin-film solar technologies. So these projections do not include nanotechnologies, desktop manufacturing/3D printing (a sure thing), availability of needed materials (China, etc), regulations or other unforeseen economic roadblocks.
Fact 1: The slowest growth period for installation of Solar Power was between 1990-2000 at 20% annually.
Fact 2: The fastest growth period for adoption of Solar Power was between 2004-2009 at 60% annually.
Fact 3: Total installed Solar Power as of November 2010, was approximately ~25 Gigawatts.
Fact 4: Total World Power Capacity is ~17 Terawatts (as of 2010).
Fact 5: Useable Solar Power is only 1/3 of the time in sunny areas, so practically speaking we’d need 51 Terawatts of installed Solar to match current needs.
Using basic logarithmic functions I wanted to see how long it would take Solar at the above growth rates to reach 17 Terawatts.
SLOW (20%) – Log (1700/25) / Log (1 + 0.20) = 41.2 Years – Solar reaches current World Power Output by 2051.
MEDIAN (40%) – Log (1700/25) / Log (1 + 0.40) = 22.3 Years – Solar reaches current World Power Output by 2033.
HIGH (60%) – Log (1700/25) / Log (1 + 0.60) = 16.3 Years – Solar reaches current World Power Output by 2026.
Even if we take the Median projections based on average growth of Solar over the last 30 years, we get Solar reaching current World Energy needs by 2033. Since world energy needs continue to climb, then there is no reason why at a median 40% growth rate, Solar could not meet all the electricity demands of the world by 2030.