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This page will have my own opinions about solar energy, but I will gladly include references to other opinions. The Wikipedia page on solar energy looks up-to-date as of 2007 and will presumably be kept up-to-date.

The applications of solar energy include powering earth satellites (successful), powering emergency telephones along highways (successful), heating water with rooftop installations (successful but at best marginally cost-effective where energy is cheap), electric power where grid energy is not available (apparently not cost-effective at present compared to diesel generators) and central station electric generation (not presently economical). This paragraph was written in 2003, but I think it is still accurate.

It's now 2007 June, and solar central stations are still not economical.

Central station generation is the application that needs to be compared to present generation methods - burning coal, oil or natural gas or nuclear energy. We have a separate page on nuclear energy.

Like nuclear energy, solar energy does not put CO2 into the atmosphere, and so needs to be considered if global warming has to be avoided. It has lots of supporters, especially among those who oppose nuclear energy.

There are many schemes for generating electricity from the sun. These include
  1. Photovoltaic cells. These are an attractive field of research, and have gradually been made more efficient and less costly.
  2. Power towers. Mirrors focus sunlight on a boiler, which generates steam and then electricity. Here's a Boeing power tower project. The Boeing URL died, so maybe the project has also died.
  3. Burning biomass. This competes with other uses of agricultural land and requires more labor than present energy generation methods.
My opinion is that except for special applications, solar energy is a resource and not a reserve, to use economic jargon. This means that our civilization would survive if we were dependent on solar energy, e.g. could not use nuclear energy. However, solar energy would be expensive enough to put nations that decided to depend on it alone at a serious economic disadvantage compared to nations that were not constrained to rely on it. Their citizens would be poorer.

The basic cost problems with solar energy are

  1. High capital cost. This is probably not insuperable.
  2. The need to store energy, because of daily, hourly and weekly (from clouds) and seasonal availability.
  3. The need to transport the energy long distances. This might put cloudy countries at high latitudes at a severe economic disadvantage.
  4. Maintenance cost. One person, experienced in maintaining complex systems gave me an estimate of one percent a month, e.g. a system costing $40K costs $400 per month to maintain.
There will be more discussion of specific solar schemes on this page. Comments and suggestions to deal with particular issues are welcome.

Solar Power Satellites

Solar energy is more easily collected in space than on earth. The solar collectors can be permanently aimed at the sun, and there are no clouds. This has given rise to proposals for solar power satellites that would collect solar energy and beam it to earth using microwaves. The energy would be beamed to rectenna fields that would rectify the microwave beams and distribute the energy to users.

Advocates of solar power satellites make quite favorable cost estimates, but others are more doubtful about the costs, especially launch and construction costs. The International Space Station will doubtless yield information about such costs. 2007 note: Launch costs have proved much to high. I think SPS will remain dormant until this changes.

Here are some articles by advocates of solar power satellites.

"Solar Power Satellites: An Idea Whose Time Has Come" by Seth Potter, New York University,

"The World's Energy Future Belongs in Orbit" by Dr. Gerrard K. O'Neill,

"Solar Power from Space" by Texas Space Grant Consortium. The last two urls are dead.

Another SPS advocacy site It's not an SPS site any more.

SPS2000 is a Japanese proposal for a small system in low earth orbit.


There is some recent optimism about wind power. Kenetech is said to be building wind turbines capable of generating electricity at 5 cents per kwh. (1997 note: Alas, Kenetech, said to be the leading builder of wind power systems, went bankrupt some time in 1995 or 1996). There was said to be a 500MW plant being built in Carbon County, Wyoming. Another significant build is said to be in the Guadaloupe mountains in West Texas. It will be interesting to see if the cost estimates hold up after the plants are built and if there are enough suitable sites to generate a substantial part of the country's electricity. (I'd change "said to" if I had links to references.)

There is information about wind power and other forms of "renewable energy" at the National Renewable Energy Laboratory. This laboratory hopes to demonstrate technology capable of 4 cents per kwh electricity by the year 2000. Electric Power Research Institute (EPRI) has additional information. Here's a reference to some surveys on the public acceptablility of wind power.

Here's a page Solar Energy by some enthusiasts.

1997 August 16: The San Jose Mercury has a story today datelined Washington about the U.S. solar energy industry. Here are some highlights:

  1. Sales last year amounted to $850 million. (This is less than half the cost of one 1,000 megawatt power plant.)

  2. The industry relies heavily on exports, and the Government wants to reduce that dependence.

  3. The U.S. Government has put $1.5 billion into solar research in the last 25 years.

  4. President Clinton announced a "million solar roofs initiative" intended to achieve that by 2010 - either photovoltaic or hot water heating.

  5. California will give $54 million in solar subsidies next year.

  6. 18 states require utilities to buy power from residents and small businesses at retail rates. This is a real racket, because the power is produced whenever the householder has it available rather than when the utility needs it. The effect will be to put peaks into the utility's power requirements curve. Of course, it won't matter if the amount of power put back into the utility's system is very small - which may be likely.

  7. Here's the last sentence of the article:

    But because the utility industry's power grid is so extensive, and its output so inexpensive, only about 30 percent of solar-power sales are within this country. For years to come, solar cells will probably be too expensive to compete directly with electricity from the power grid.
Once an industry (or other activity) is created by subsidy, it is very hard to get it to stand on its own feet. It has lobbyists who influence Congressmen and other Government officials. The solar industry also has an ideologically motivated constituency. We are fortunate that its subsidy isn't much larger.

You can download "A Consumer's Guide to Buying a Photovoltaic System" at

I read the guide and it seems accurate to me.

1. Your photovoltaic electricity will cost you $.25 per kwh.

2. You don't pay property taxes on photovoltaic systems. This constitutes a subsidy.

3. In most of Wisconsin, the utility has to buy back your excess electricity at retail prices whenever you have an excess. In other places the utility only pays avoided cost, which may be as low as 1.5 cents per kwh. This is another subsidy, coming ultimately from the utility's other customers.

4. You can legally prevent your neighbors' trees from growing tall enough to shade your site.

My impression is that the reader of the guide will have to be a reasonably wealthy enthusiast to do it on the basis of the information provided.

It would be interesting to know how many systems there are in Wisconsin and whether installed systems continue to be used.

There have been news stories early in 2001 about wind systems about to be built in Washington that would produce electricity at $.06 per kwh, later to be reduced to $.03 per kwh. However, at present the state of California is taking proposals for fixed price contracts to produce electricity, and apparently all the proposals being submitted are for natural gas powered plants.

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