Turn On the Heat

When I was eight years old or so, my mom took us to the local lake. It was a particularly hot day and I put on sunscreen. After hours of fun in the lake, we came in for a picnic lunch. I was crispy. The swim suit straps had saved only a narrow stripe of skin on my otherwise bright red shoulders from the suns rays. My first sunburn.

All that energy. Right into my shoulder. The sun is the source of energy on earth. So why do we harness it so indirectly for our own energy needs?

According to the Energy Information Administration 2006 Annual Energy Review, 6.8 percent of the U.S. energy supply comes from “renewable” sources. “Renewable” energies include hydroelectric power, geothermal, solar/pv, wind, and biomass. However, within that figure is also petroleum derived ethanol.

I’m now looking for a figure that says how much “renewables” we used to consume. For as pitiable as 6.8 percent is, it will look good in comparison to ten years ago. But, I am distracted by a chart (also from The caption says, “The United States was self-sufficient in energy until the late 1950s when energy consumption began to outpace domestic production. At that point, the Nation began to import more energy to fill the gap. In 2006, net imported energy accounted for 30 percent of all energy consumed.” Furthermore, since 1988 we have not significantly changed consumption of Btus per person. These charts are really interesting. I could tell you all about them, but I’m losing the point of this post. Go check it out for yourself.

The point of this post is solar concentrators. We’re going to develop one. Meaning you and me. Marcin asked me to help move the open source solar concentrator design forward. The problem is, I don’t know much. But you do or one of your friends does. Somebody out there does. Help put me in contact with them. Send me your best links and ideas.

The ground rules are as follows:

1. Although efficiency is important (the more efficient the better), highest efficiency is not our first design criterion.

2. What we are interested in is the most cost effective (ie,  efficient for the price of construction and maintenance), most replicable, simplistic design.

3. The goal: people can begin producing these and compete with subsidized energy. I know, that sounds unfair. But honestly, Americans are not going to accept “renewable” energy unless it looks and quacks like its subsidized counterpart.

4. Scaleable. A DIY home-brewer should be able to build one in their backyard. At the same time, a small-scale entrepreneur should be able to supply energy to an entire town using the same method, scaled up.

5. The concentrator will produce heat. That heat will be eventually turned into electricity. The current thought is a boundary layer turbine.

6. Marcin thinks a flat concentrator (rather than the more popular parabolic design) is the best route at this point because it requires minimal structural support (reducing costs) and is more easily scaleable. Is this the best method? What do the design details look like? Should oil or water be used as the medium in the collector? What’s the best angle for the mirrors? Where’s the best place to locate the collector in repect to the mirrors? Will 16 fold magnification create enough heat? Is 4’x8′ good for one panel size?

I realize these questions are a bit out of context, but I threw them down to get thoughts started. The solar concentrators wiki page may help put it into context, if you want more info right now:

So, pick your brain and your neighbors brain for ideas. Click the comment button, and share your thoughts.
And as always, if you are interested in leading or contributing to the other projects, let us know!


  1. Dale

    How would we get an account to work on the wiki?

  2. Marcin

    The wiki was opened up again, after temporary shutdown due to spam attacks. We installed Captcha to prevent robot spam. You can create an account and log right in.

  3. chris


    i have several links and contacts for you but didn’t want to post here (to prevent comment from getting spam filtered)

    would love to connect with you folks.

    please email me and i can email you the links.


  4. reyesc

    have you seen the TED talk by bill gross

  5. home made wind generators

    Well written stuff ,, will visit

  6. Vipen Mahajan

    I am in New Delhi. Some folks here have developed/made the Schefeller parabolic solar concentrator. 2.5 and 7.5 M dia. They are training rural folks in village level construction. I was looking at this design for rural electrification, as well as for solar cooling.
    Pl. let me know if this is relevant to ur plans.
    Vipen Mahajan
    SKype ID vmahajan

  7. Jeb

    I searched a bit and found the following sites on the above parabolic concentrators…
    Interesting focus on a stationary target. Parabolic is certainly useful for high temp.