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Open source tracking solar concentrator from recycled materials.
  • Hi all. For the last to years I've been developing the prototype for a tracking solar concentrator, which is now working.
    Last month we had the first free construction workshop, and I'm in the process of putting together a tour of European ecovillages, communities and festivals for the summer if you want to come along (for free).


    The SolarFlower is a free and open source solar device which tracks the sun during the day and collects energy in the form of heat, which can then be used to run various applications such as water heating and purification, electricity, cooking, biochar, biodiesel, etc.
    It can be made from recycled materials and common household items using very basic tools and skills, and there will be detailed animated tutorials on how to construct and use the device and its applications.
    Over the next few years I plan to travel with the project, working with local communities and NGOs, giving free workshops and working in with people on how to build and develop this technology and others.

    More information at

    First Solarflower tracking - time lapse.

    Basic walkthrough of how the solarflower works.

    Solarflower engine turning over.

    I'm in the process of getting animations together on exactly how it works, til then feel free to ask.

  • 12 Comments sorted by
  • No interest huh?
  • Well it is interesting, but where are the goods?  The solarflower page is down and I can't find the links to the build instructions on the blog.
  • Hadn't seen it till now. Thanks for bumping it. The tracking mechanism is really innovative. I think overall it looks like a great design. This is the type of thing that could potentially be used in the bootstrapping process when setting up the basics. I can see the need for a smaller solar power system in conjunction with a larger one. The smaller one is built first and is primarily for lighting, communications, and light machines. After that is established, the larger boiler-version is constructed to run the heavy equipment.
  • Gregor:
    Yup, that is what it comes down to. I'll have the main website up hopefully by the end of the week, but the tutorials will unfortunately have to wait a couple weeks more. Not how I'd like it, but I'm crazy busy with a half dozen projects at once.

    Quick basic systems which enable the implementation of heavier ones... good idea. I'll give that some thought..
  • Nice design. Could you give some specifics like the dimensions of the parabolic collector, maximum temperature attained and the total output power (rough approximations? Can it be used to drive a turbine?
  • The reflectors on the two prototypes so far have been a square meter aperture. I'm pretty sure the tracker would drive a collector at least twice as large, but let's go with this for now.
    I haven't had a chance to actually measure the thing yet, but it should break down something like:

    One square meter full sunlight is about 1,000 watts.
    The aluminium I'm using would be at least 80% reflective, but with a half decent polish should come up to at least 90%, possibly higher.
    I've been using plastic bottles for the cladding around the collector pipe, which could be as low as 50% effective, so would advise an evacuated tube if you can get your hands on one, they're about 90%.
    The rest of the system can be excessively insulated, and uses a thermosyphon action to move the heat, so you're probably not going to be losing much there, let's say 90%.

    This gives something between 360 and 730 watts usable overall, depending how nice you make it. I usually think of it as about 60%, but like I say it all still needs to me measured.
  • And yeah, should run a turbine, tho you'd definitely have to run an evacuated tube to get up to the 600 C for dry steam.
  • Have you looked at my idea- A Simple design for a cheap Solar Thermal Collector. I want to try a different version of the idea. I want to take a transparent plastic sphere (about 1.5 meter diameter) and fill it with water so it acts like a lens. I want to see what is the temperature at the focus of this lens and can it be used to drive a Stirling engine to generate a few hundred watts. Unfortunately i don't have the means to do it myself right now. Could you build a lens like that? You could use it along with your sunflower project. Sun-tracking for a lens like that could be very easy since you don't have to move the entire apparatus , you only have to move the engine along the focus arc.
  • Here's is a diagram showing the sun-tracking of the above lens.

    Solar Thermal Collector_Sun-Tracking.JPG 35K
  • Yeah, with a bit of a redesign the tracking system would quite easily track something like that.
    I was thinking of a water lens as well, but a flatter, double paraboloidal one. It would have a longer focal length than a sphere, but be very easy to make and focus. What would you make the sphere out of that it didn't deform with the weight of the water?
  • I have been thinking about the weight problem myself. I want to try two concentric transparent spheres with water filled in the space between them.This should reduce the weight. But the weight should not be reduced to an extent that the lens can be blown away by the wind. The round shape of the lens should provide a good protection against wind anyway.
    Lens.JPG 19K
  • Full construction tutorials and other resources are now available at

    Ten points to the first to make one.

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