SoharaDotOrg

Improvement on design[]

The mirrors used in the SoharaDotOrg must be curved as per the design idea from SolarLinks#OPTIONS A square piece of plastic has cross sectional ribs glued from corner to corner in a X shape. It is glued at the center. Near the edges on the rib, a threaded bolt is screwed through to generate a curved parabola shape of of the square mirror. http://www.solarfire.org/tech/helios/helios.html removed the photos and explanation of how they micro adjust a plastic reflective covered mirror in parabola shape with four bolts and two ribs

Directing energy to fiber cables[]

The directable mirror energy are funneled through a fiber cable to create a small area heat source for driving a SolarTurbine or StirlingEngine as per various patens from FresnelLenses. Multiple of these http://www.Sohara.org directable mirrors are aimed at a FresnelLens which concentrates the energy into fiber cables. The fiber cables are collected at a central focusing point , focusing the suns energy from say a 100 square meters unto an area of 10x10cm. Previously this was only possible using a huge 10x10 parabolic mirror making it unviable from a cost perspective.

Directable mirrors[]

Australian patent no. 722115, US Patent no. 6227673, Patent pending Europe

ref -

Silvered-PMMA reflectors, "Solar Energy Materials and Solar Cells 33" (1994) 183-197, Paul Schissel, Gary Jorgensen, Cheryl Kennedy, and Rita Goggin
An Array of Dirrectable Mirrors as a Photovoltaic Solar Concentrator, "Solar Energy", vol. 24, pp. 221-234, (10/78), W. B. Ittner, II

Directable Mirrors - Introduction The Problem Solar power installations are too expensive to be profitable. The normal method of concentrating solar energy is to use one or more large parabolic mirrors or parabolic section troughs which are moved to track the sun in order to focus it on a chosen area (a line in the case of the trough). An alternative method is to use a large number of small flat mirrors, each tracking the sun to focus on the same target as the others. In this arrangement the individual mirrors do no focusing, this is achieved by all the mirrors pointing to the same target. Existing designs make each of these approaches too expensive to be practical, although a number of experimental and partly commercial installations do exist. The essential problem is the cost (and weight) of the precision equipment required to direct the mirrors, especially as they have to work exposed to the elements for long periods of time. The Solution Inexpensive Directable Mirrors. An inexpensive panel that acts as a rapidly directable mirror while remaining externally fixed and sealed would make the 'many mirrors' design practical. Ideally such a panel would require little energy to direct, would be easily mounted, robust, light in weight, and easy to install. This impossible sounding device is exactly what this site is all about. It has all the above and more, follow the links below to learn about it.

Directable Mirror - Assembly[]

http://www.sohara.org/assemble.html. A simple task. Just bolt the panels and controllers to the support (wall, posts, earthbank, whatever), hook up the cables, stick in a couple of posts for the sensors, hook them up and calibrate the array. Unlike other solar concentrators, there is no on site metalwork, no delivery of multi-tonne machines, no need for surveyors. The entire set for a one-hundred-square-meter concentrator will fit easily into a small van (including the Stirling engine).

Directable Mirror - How It Works[]

http://www.sohara.org/principles/index.html A Directable Mirror is an inexpensive panel approximately one meter square and a couple of inches thick. It is sealed, with only electrical connections and has no external moving parts. It is capable of rapid internal movement of the mirrors. It works like this: Take two flat rigid sheets separated by a large number of balls. Move one of the sheets and all the balls will rotate. Make the balls transparent with a reflective circle stretched across their centers, and the front sheet transparent. Arrange motors to move the other sheet and you have a directable mirror.

A 'Proof of Concept' can be constructed in a few seconds with the aid of some tennis or ping pong balls, a flat surface and a sheet of glass. Drop the balls on the surface, put the glass sheet on top and move it with your finger. Now, for a comparison, take that sheet of glass outside and try and hold it still in a high wind, which is what a conventional concentrator has to do. If the sheet is much larger than a mirror tile you probably cannot hold it still, let alone aim it accurately, The figure shows the concept in a more complete form with a casing, transparent front panel, the mirror balls and the motors for moving the rear panel.

The motors move the rear panel making the balls rotate thus moving the mirrors and changing the effective direction of reflection. The balls and the front panel may be made from glass or clear plastic whichever is the most economical and effective, plastic balls and a glass panel seem likely to prove best. The rear panel has a thin layer of foam in order to reliably grip the balls and compensate for small variations in ball sizes. The details of the panel moving mechanism have been left unspecified. There are many workable mechanisms the choice is largely a production/economic one given easily achieved technical constraints on positioning accuracy and speed. A usable mechanism could easily be based around two of the the cheapest simplest stepper motors available and two rubber wheels. The device is very simple and lends itself well to mass production. The described system easily matches the requirements outlined in the introduction for making solar concentration a practical system.

Directable Mirror - Wall[]

http://www.sohara.org/wall.html You need something to hold the directable mirror panels. An equator facing wall is ideal. Anything will do that can hold the panels vertical and facing the north in the south (and vice-versa). No need for a specially built support, use what's available.

Put panels between the windows of one side of a large building or two and you have a high power solar concentrator - the target(s) go on a tower above the car park.
Lower power installations can also find existing support. One side of a barn could easily house a 40 kilowatt concentrator array.

Unlike most solar concentrators, the directable mirror panels are light and do not move. This makes them very simple to mount, no complex mechanisms to set up and maintain or find space for. Any convenient vertical support facing the right direction will do: a wall, fenceposts, or even an earthbank.

Directable Mirror - Computer[]

http://www.sohara.org/computer.html A PC with some array control software. The computer is only used to set up the array. For arrays with only one target the computer is needed only during callibration. Large installations with more than one target can be feedback controlled via the computer. Temperature sensors on a target linked to the computer are read by software which redirects elements of the array as necessary to the target. In such a system there should always be a 'sink' target to which all excess can be directed. This directable mirror panel is the only solar concentrator suitable for such demand driven applications.

discussion on dish absorbers[]

Cutting grooves in a solar absorber increases efficiency.

DeSoto has various projects such as Fluidyne Stirling engine to pump water for agriculture.

http://groups.google.com/group/alt.solar.thermal/browse_thread/thread/aca340a666e5a905# I finally tired of mentally translating C.D.West's "Stirling Engines and Irrigation Pumping" ORNL Report from gibberish to English and have turned it into a web page that /hopefully/ isn't gibberish.

I did a few repairs to the Appendix, but it's still pretty much like the original - full of transcription and typographical errors. I'll do the repairs to that as I have time.

Everyone with an interest in fluidynes is invited to look the web page over and, if you find any errors or think of improvements, let me know.

It's at http://www.iedu.com/DeSoto/Projects/Stirling/ORNL-27113.html

(such as it is / what there is of it)

solar aircon[]

http://www.techespot.com/2009/08/solar-power-for-ac.html

http://www.iedu.com/DeSoto/why.html

links[]

Solar Energy