**Even though, at ground level, America receives 3700 times as much solar energy as the 100Q of energy we produce from all sources (See Solar, Part One), solar energy cannot solve the Climate Change crisis that the Earth faces. Massively-concentrated, energy sources like nuclear plants, or strongly-concentrated, sources like wind turbines are the only available solutions.**

As described in Part One, America's 3,000,000 square-miles receive 11PKWH (11 X 10 to 15th kilowatt-hours) of solar energy each year. Each square-mile receives four-billion KWH per year. A one-gig, nuke (one-million KW), operating 90% (about 7000 hours) of the year, "produces" seven-billion KWH; 1.6 times as much as each square mile, of land or solar cells, can "receive". Since 15% efficient PV cells only deliver one-sixth as much electricity as the energy received, one square-mile of cells only gives 0.65 billion KWH per year. One, one-gig nuke can produce as much electricity as 10.6 square-miles of PV cells (265,000,000 one-square-foot cells).

As described in Part One, America's 3,000,000 square-miles receive 11PKWH (11 X 10 to 15th kilowatt-hours) of solar energy each year. Each square-mile receives four-billion KWH per year. A one-gig, nuke (one-million KW), operating 90% (about 7000 hours) of the year, "produces" seven-billion KWH; 1.6 times as much as each square mile, of land or solar cells, can "receive". Since 15% efficient PV cells only deliver one-sixth as much electricity as the energy received, one square-mile of cells only gives 0.65 billion KWH per year. One, one-gig nuke can produce as much electricity as 10.6 square-miles of PV cells (265,000,000 one-square-foot cells).

**A well-detailed report (http://linas.org/theory/solar-electric.html) docments: at average peak output of 10-watts per square-foot, 100 square-feet solar cells give one kilowatt; using battery-bank, or grid-tied systems; 168 square-feet; gives 1.92 KW, 8.8 KWH/day; in Austin, Texas; with average 5-hours/day sun; gives 3300 KWH per year. PV cells, $5 per watt; other parts, plus utility hook-up give total cost of $10 per watt, or $20,000 for 2000-watt system. To amortize this versus Texas electric costs, takes decades. Costs must come down greatly for widespread acceptance.**

**My Take: To equal a one-gig nuke, two million households must be able to afford $20,000 systems, yet still be interested in saving a small amount on their electric bills. Also, the $40 billion to build these systems could pay for ten, $4 billion nukes instead.**

## 2 comments:

The most promising solar as far as I can ascertain is the power tower version of solar thermal, using molten salt and incorporating storage tanks to allow production of power at night from the energy stored during the day.

Rooftop photovoltaic is widely recognized as not being a promising approach as a major future source of power.

So comparing nukes to rooftop photovoltaic is not a reasonable comparison.

From estimates I have seen, solar thermal with storage is comparable in projected price to nuclear, although it hasn't yet been proven in utility scale 100-200 MW plants which would be necessary to conclude with substantial confidence that it can serve as a mainstay of our future energy infrastructure.

Solar technology is constantly improving.

solar energy

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