World Solar Power
World Wide Photovoltaics
The total world wide photovoltaic peak power at the end of 2012 is 102 gigaWatts at peak overhead illumination, where a gigaWatt (GW) is a billion Watts or 1,000 megaWatts. Germany has a third of this at 33 GW, Italy is next at 17 GW, China at 8 GW, the US at 7.7 GW, and Japan at 6.7 GW. These solar enthusiastic countries total 73 GW, or over 2/3 of the total. The data are from Wikipedia.
Normally, we use a “capacity factor” of 1/5 on solar power which means the hourly and yearly average of power produced is 1/5 of the peak power. However, looking at the yearly energy output of the above countries which are further North than California, they are generating with a capacity factor of only 1/10, except for the US. So for 65 GW world wide in the leading countries without the US, using the 1/10 capacity factor, gives an average output of only 6.5 GW, equivalent to about 6 US nuclear reactors.
World Wide Concentrated Solar Power
World wide solar concentrated by mirrors only added up to 1.7 GW, with major plants in California. This is less than 2% of world wide photovoltaic power, because it is more expensive.
US Solar Power
Solar power has made incredible strides in reducing the cost of solar cells to about $1 per Watt. However, with packaging and installation, it is about $2.30 per Watt for utilities, and about $5 for residential, and $4 per Watt for commercial. Solar of course varies by day and night, by season, by solar transit, and by weather and clouds. Its capacity factor for average yearly power is about 1/5 of its maximum, full overhead sun rated power. So to get an average of a Watt year round effectively, you need 5 one Watt cells, or at utility pricing, $12 for a yearly averaged Watt. However, you may have nuclear or natural gas for steady background power, and just use solar as a daytime supplement and price it closer to the peak power value. Double however, the peak power is really needed around 5-6 pm, when solar isn’t much help. At $12 a Watt, a solar plant producing the average energy of a 1 GigaWatt nuclear plant would cost $12 billion, which may be the same cost as a nuclear plant or twice as much. I compare nuclear here since both are mainly CO2 free. Expensive, rapidly varying natural gas plants are needed to replace solar power when it fluctuates.
Total US solar power is now at 7.7 + 1.7 = 9.4 gigaWatts. Solar’s capacity factor of 1/5 reduces this to an average power of 1.9 gigaWatts, or the equivalent of about two US nuclear reactors. Still, if base power is provided by nuclear power or fossil fuels, solar could be taken as closer to its peak power as used for the increased power needed for maybe 9 AM to 3 PM.
We note that California is the top solar US state, and New Jersey (why?) and Arizona have peak power of about 1/3 of that each. The utility plants are mostly in desert areas giving them high amounts of solar on freely provided federal land. They either track the sun vertically or completely, and can be 30% more effective than rooftop power that is not tracking. Also, people don’t often have roofs that point Southward, nor do they align their systems to the angle of the latitude, which here is about 34°, for maximum yearly exposure. The solar cells must also be cleaned regularly by water.
What can’t be done by your utilities is solar hot water heating. A home system costs only $6,000 as compared to a rooftop solar system around $20,000. It is much cheaper than rooftop solar, and just as good for the environment. When you travel in Mediterranean or tropical climates you see lots of rooftop solar hot water systems.
