I just found a couple of studies about projected installations of power plants over the next few years. One, by Gerry Runte of Greentech Media Market Research, predicts that there will be between 78 and 91 gigawatts (GW) of nuclear capacity installed worldwide between now and 2020. That accounts for projects with a probability between 10% and 90%. The most probable number is 84 GW.
According to the research firm IHS, 2013 should see the installation of 35 GW of photovoltaic (PV) systems worldwide, up from 32 GW in 2012. The IHS projection through 2017 is that the PV market will rise to 61 GW annually, with a 2013-2017 total of 242 GW.
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If we project that the 2010-2017 average growth rate of 17.6% continues, annual PV installation would reach 99GW in 2020, for a 2013-2020 total of 497 GW, 413 GW more than nuclear. Of course, sheer capacity isn't the whole story. Not every power plant runs 100% of the time.
According to the Nuclear Energy Institute, the industry average capacity factor for nuclear power plants is 86%. That is the comparison between how much energy they actually produce in a year and how much they would theoretically produce if they ran 100% of the time. In reality they have fueling and maintenance outages as well as unscheduled shutdowns.
The capacity factor of photovoltaic systems varies according to the local climate. In the continental U.S., the output of a 1,000 watt system might vary from 1,100 kilowatt-hours annually in Seattle to 1,700 kWh in Dagget California, in the middle of the Mojave Desert. Given 8760 hours in a year, this is a capacity factor of between 12.5% and 19.4%. Call it an average of 16%.
Apply that to our projected 497 GW and in 2020 the 2013-2020 PV installations would be producing 79.52 GW-hours annually. Meanwhile, that 84 GW of nuclear at 86% capacity will be producing 72.24 GW-hours annually. That is, if there is enough nuclear fuel at an affordable price. I imagine that the sun will still be shining in 2020.