Tuesday, August 07, 2012

diy solar parabolic trough gen2 intro

In 2010, I wrote "How to build a Tracking Parabolic Solar Collector" describing my self designed and built working prototype and test results. I tried to show what a determined person can do with ordinary tools and materials, a good hardware store and a bit of perseverance - a high performance Do It Yourself (DIY) solar heater.

Since then, I have had lots of great feedback from the 600+ people who bought the book and Thank You for that!

[updated March 2014] Over the past four years, I have improved the design. This improved design is described in detail my new book "Solar Parabolic Trough Concentrator: Home Experimenter's Manual".

gen2 intro reading list
build a tracking parabolic solar heater project background
gen2 intro (this article) reader projects/testimonials
gen2 solar progress solar tracking motor explained
gen2 solar progress 2 matching reflector length to collector
how to make solar superheated steam weatherproof solar tracking housing
solar squeegee - how to clean compare this to flat plate collector?
a parabolic plant light new book update
gen2 hanger description video (YouTube) new book update 2

Improvements

The reflector design has been simplified. I have done a series of measurements and started working with glass evacuated tubes as insulators for the solar collector to enable higher temperatures and winter use.

Gen2 design goals:

Simpler hand or machine made ribs In the original version, there were three different types of ribs - now one rib does all three jobs. The new rib is simpler and lighter. Thirteen can be made from a 2x4' (30x60 cm) sheet of material, only seven of the original could be made from a sheet this size. The ends of the rib are simplified to suit angle profile side channels which should be available anywhere.

I show the methods I use to make small quantities by hand using patterns. I provide .dwg files for CNC laser or water cutting for larger quantity production.


(click any pic to enlarge)

Simpler side channels I show how to use a standard angle profile in a very strong and precise joint that can be made by hand or machine. Different materials can be used, to suit what is locally available. The resulting reflector assembly is robust yet light weight and completely grips the reflective sheet along the long edge and supports it accurately from below.

Better balance, more efficient Each reflector assembly is balanced before installation. Balancing ensures that minimal force and therefore energy is required to position the array. In this way, different material can be used and the assembly adjusted just once for any resulting balance shift. I think I should be able to swing up to 25 reflectors with the existing motor drive with this new method.

Insulated, high temperature collector option I show how to suspend a standard glass evacuated tube at the focus and use it as a large thermos bottle to surround the collector. Higher temperatures and or winter use are thus made possible with this design.

A ball bearing support and a much stiffer reflector frame will make high altitude use possible (near vertical mounting). You can use this either insulated or not.

Flexible size I will show you how to make several different sizes of collector. All are based on the same parts.

You can make this in your garage You need some basic woodworking tools. I have improved some of the methods. It will take less time to make.

Please show your support by buying my books. My work is supported by book sales. Perhaps you've noticed that I haven't monetized these pages (no ads)?

The index at the top of this page takes you to articles on this blog about gen2.

Thanks as always for your feedback and Thank You for your interest.

George Plhak
Lion's Head, Ontario
Canada

10 comments:

Anonymous said...

Hi George, congratulations for your great job and thanks for sharing it with everyone! I would like to know how much time does it take to build one of these collectors. Thanks!

frazelle09 said...

Hi George. Ditto to the previous comment - great job!

i bought your first book last year since we were looking for some tips for the collector that we had built. It is based on sheets of 10' x 4' galvanized sheet metal which we cover with Mylar 2 mil film. It works great! We're still looking for a better way to make the Mylar stick to the metal. Our first try was axle grease - lol. Your vacuum tubes look even more promising - maybe we won't have to use so many collectors, but we'd have to cut our model down to your size - maybe we could get the metal store to chop them to the correct size.

Question: Should we go ahead and buy your second edition...?

Again / great work and thanks for sharing! :)

Anonymous said...
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Joshua Wine said...

Hi George,

Great site. How do you circulate the water through your collector? What materials do you use to circulate the hot water? I imagine it has to be pretty tough to handle the temp. I am hoping to make a system that can generate some pretty high water temps and circulate that water through a pot to boil a separate fluid. Does you book cover topics like this? If not any idea on where to look? Thanks for you efforts in pushing the DIY science.

George Plhak said...

Thank you Joshua for your interest.

In the high temperature tests I did (please see first steam test you will see that I did not circulate the water so a high temperature pump was not an issue.

There are pumps built to withstand temperatures near that of boiling water. I have not needed one yet myself.

I only plan to cover the collector in the new book. You might look at builditsolar.com for ideas?

Best regards, George

George Plhak said...

Hello frazelle09 and anonymous

How much time it will take you to build your collectors I cannot say and will depend on a lot of things including the methods you use, your own skill level and any changes you make to the design (like you have done frazelle09).

I am getting set up in my new home and will shortly I hope be able to work again on Gen2 in earnest.

Your buying my books helps me to continue my work. Thank you. George

red8310 said...

love it love it, I have bought the gen 1 book, but haven't built anything, I'm waiting for gen 2 book to be released, my question is, have you tried/tested using manifolds across the top and bottom, probably 2", and if it is running the same volume, wouldn't the BTU's be the same as the inline system?

Ian Garrow said...

How is your latest (gen2) book coming along? I see the biggest change is to the ribs (only one style and edge shape different). I've just bought Gen1 and would like to start making my first one soon, after I've acquired all the material here in the UK.

Christopher Schoonover said...

Just out of curiosity; Have you tried using passive solar tracking systems with your parabolic collector. I'm specifically thinking about compressed gas that creates differential pressure when heated on one side or the other shifting the angle to create equal pressure (aligning with the sun)

George Plhak said...

Like the Zomeworks?
No I haven't.
George