Department of Agriculture

[eppie]

I once read an article that said if one (government) were so inclined, they could take a 100 SQ Mile section of desert (the article proposed somewhere in New Mex/Ariz/Southern California) and with the use of solar panels, batteries, and the like, they could power the lower 48 indefinitely.

The resulting jobs would be a boon, the power would be a boon.

The article cited issues with getting it up and going, and the startup costs being massive as major hinderances. I'm sure that there are also fantastic logistical concerns, science problems, and the like with the proposal, and 100sq miles of solar panels = how much space to handle the rest of it?

But, it was nice food for thought.

The solar power hitting the Earth is about 1000 Watts per square meter in full sun at sea level. The efficiency of solar panels is increasing, but let's assume 15% of that power can be converted to electricity. Early in the morning and late at night solar panels have a much reduced output with maximum output near noon. A good rule is you can get the equivalent of about 42% of maximum output per 12 hours of sunlight - less on cloudy days. So a one square meter solar panel should provide 0.42 x 12 hours x 150 watts = 756 Watt-hours per day.

The US consumed 3961559000000000 Watt-hours in 2009. So, 3961559000000000 Watt-hours / 365 days) / 756 (assuming 12 hours of sun every day) works out to 14356595640 square meters, or ~5540.3 square miles. That works out to a square area about 74.4 miles across. And, that would be a solid collection surface. Realistically you could double that for spacing of collectors, and what not. I believe in distributive networks, so rather than one mega site, I'd rather see about 20 or so distributed sites.

The down side is that the first 6 years would be used to pay back the energy costs of building the solar panels. After that, free energy. Well, perhaps not entirely free with maintenance (keeping the dust off them and etcetera... Then, they'd need to be replaced at end of life which may be 15 to 20 years I would guess. The approximate cost per square meter is £250 or about $390. That works out to a project cost just for the panels of 14356595640 * $392 = ~ $5.620 trillion

So, lets for simplicity we need about $7.5 trillion every 20 years to build and maintain the infrastructure to provide power for about 312 million people. That's $7.5 trillion / 20 years = $370.5 billion per year, and for 312 million people is about $1200 per person per year. Pretty good expensive. And, due to weather and seasons, and nighttime, we'd still need some other form of power production or storage for the non-sunny times.

Edit: Multiplied everything by 10... Thx Jester.

Kandrathe, I am just following this thread just now but I would like to comment a bit. My father just placed solar panels on his roof (silicon single crystalline from china). I am not absolutely sure but I think they are 50 cm by 1.5 m or so (0.75 m2) and he has 14 of them (2 sets of 7) so 10.5 m2 for a total cost of around 400 dollar per m2 I think. He make around 12KWH on an average cloudy dutch summers day and indeed payback time was estimated at around 6 to 7 years. (which to me means everybody not putting them on his roof is an idiot).
Anyway the thing in Holland (one of the worse developed countries imn the world when it comes to supporting alternative energy) is that you can deduct what you generate from your usage. The cost for a KWH are around 25 eurocents I believe, but if you produce more than you use in a year you sell the extra back to the el company for a price of 7 cents per KWH.

Point is in Arizona payback times would be no more than 3 years if you ask me (you can use less cells in a series to reach the same voltage for example). There being so much more sun then in Holland (less cloudy days, better angle etc).

The only factor infuencing an economic choice here is what you pay for grey electricity. Still, in most of the southern states in the US every person with a house can generate all of the electricity he uses without a problem, and whithout very high costs.
And don't forget that solar cells are getting cheaper every year. And those silicon ones are low maintenance and apparantly very robust as well.