US Solar Installations Rising Rapidly
Despite the bankruptcy last week of Abound Solar, a government subsidized solar manufacturer, solar installations have been rising almost geometrically over the last few years.
The chart shows solar installations in megawatts, with photovoltaic panels in blue and concentrated solar power in red. Photovoltaic panels convert sunlight directly into electricity, according to the effect discovered originally by Albert Einstein in 1905. Concentrated solar power focuses the sun's rays on a central point through a configuration of mirrors and uses this heat to boil a fluid, which runs an electric turbine. Concentrated solar works best in large complexes in the desert while PV panels do better on rooftops. The vast majority of installations in recent years have been in rooftop PV panels.
A thousand megawatts represent the output of the average coal plant or nuclear reactor. Although total solar installations did not go over 100 MW until 2006, they quickly accelerated to 1000 MW last year. The trajectory is likely to rise even faster in the future. Of course the installed capacity of solar does not equal its output. A 1000 MW coal plant averages 800 MW over the course of a year and a nuclear reactor averages 900 MW, but solar panels or mirror formations only average about 250 megawatts of output because the sun shines with full intensity only a few hours of the day. Thus, the 1000 MW of solar installations in 2010 is really only the equivalent of 250 MW of coal or nuclear.
Solar is likely to play an increasingly important role in meeting peak periods of demand. Electrical consumption is usually highest in mid-afternoon and early evening and these periods generally coincide with solar's best output. Thus, solar is likely to replacing peaking power, which is now provided largely by natural gas turbines. But it is not likely to be displacing too much coal or nuclear, which both provide baseload power, that is, power that is available all the time.