georgesworkshop

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
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
Lions Head, Ontario
Canada

Sunday, June 17, 2012

best light at least cost - about testing bright diy leds at home

This is a very bad picture of a remarkably bright LED (if you click, it enlarges). This LED is running at only one tenth of it's rated power, with only one watt of electrical input yet the light is blindingly bright to me. I am trying find the best LED to use for an DIY outdoor lighting project here.

LEDs like these currently light the walkways outside my house but mine are MUCH brighter than "consumer" solar/battery LED outdoor lights available at the home centers that die after a year, or even many LED wired types you can buy.

My outdoor lights cost almost nothing to operate. Home made, safe and reliable outdoor lights that I can make with a few tools and a bit of DIY (Do It Yourself) attitude. You can change the design to suit your own situation. Solar powered, run with batteries or line power (or any of these in combination) they are very bright but hard to take a picture of.

There are a couple things going on with the picture. I am learning how to use my new iPhone 4S which is a delight but at times a frustration, like any new tech I guess. Second, I am trying to show you a very bright light source in a dark room.

All the same, I thought you might get the idea - this LED is impressively bright. This is one of a batch of LEDs I am testing for my outdoor DIY lighting project.

I want to make a pleasing and durable DIY outdoor light which uses minimal electricity in my own home workshop at a (hopefully) reasonable cost. I will show you in this series what I did. Other projects are going on around here, stick around if you can.

The particular LED I am using in this picture was off Ebay but that's not important. I am not recommending a particular product. It's about how to do this. The technology and the vendors may have changed by the time you read this, but if you go about it this way, hopefully this information will be helpful to you.

Here is that particular LED I am testing in a MUCH better IPhone pic). You can see from the lighter how small it is.

There are many different types of LEDs available: DC/AC, voltage, mounting method, big and small at all level of cost.

This is about how I compared what I had available to me.

I used some inexpensive test equipment to help me and some simple science. Accuracy is important, but not super critical since we want to compare alternatives between LEDs. Stability and operator care might be more important.

I set up the key test/experiment on a tabletop in a few hours and I had very useable results to compare different LED light sources easily. Your mileage may vary of course.

Thank you for your interest.

George Plhak

diy landscape lamp reading list
a very bright 1 watt diy led garden light
making a lamp from a 2x4
best light at least cost - about testing bright diy leds at home - this article
diy testing of led lamps
diy 1 watt led update
diy garden lamp progress
a shielded low power diy garden lamp
diy lamp update

Thursday, March 01, 2012

making a lamp from a 2x4

I am making this prototype of my ultra low power LED garden light from wood, probably spruce. This is the most common form of domestic construction material around here. It is not normally used outside but from my experience it will stand up well above ground and will turn an attractive weathered grey color with one or two years outdoor exposure. Certainly suitable for a prototype. The wood is easy to work with.

The 2x4 I am using had air dried indoors here for a couple months and shows no warping or checking. Because of the small pieces, it was easy for me to cut three good looking pieces without major knot holes. The step joint at each end gives a bit of additional strength and was easy to make with my radial arm saw. A couple of screws hold each end in place with the block clamped in the center until the weatherproof glue dries. The recess and the slots were cut with a router and a 1/2" bit. In this version, I have given the interior two coats of white paint to help defuse the light from the ends of the block outward.

The glass block slides snugly into the U. It will be fastened in place permanently to help weather seal the LED. On the prototypes I will lock it in place with a removable method of some type so I can get them apart. The half size glass block that fits this frame costs about $25 here, the LED about $20 so there is some salvageable value to the prototypes until I get things worked out with the design. I will seal the final version.

I've make some changes to this second version and refined it somewhat. The basic idea is the same. The LED which lights the block fits in a recess carved in the frame center, adjacent to the glass block. Here is a closer look. (click any picture to enlarge it)

This is one of six types of LED arrays that I have tried and which I will write about. This one is from Princess Auto, their product number 8381063, "5 x 2-3/16 in. Interior 10 LED Vehicle Light". It comes with a polycarbonate lens which I decided not to use, thinking that the glass block did a pretty good job of scattering the LED light.

Although the Princess Auto was not the brightest or most efficient LED I tested, it does provide a nice uniform light and is itself weather sealed. The first prototype which has been working outside for a month has one of these LEDs in it so I will be able to compare the orientation difference with the same source light. This one I plan to aim downward, rather than horizontally like the first.

This is a view of the end of the lamp frame showing the wireway for the electric feed. The wire will come straight out for horizontally aimed and down the slot for a vertically downward aimed fixture.

This LED from Princess Auto uses 111 mA at 12 VDC (only .111x12=1.33 watts) to provide 22.2 foot-lamberts of light in my tests. From the prototype already outside, this amount of light lets me see the stairway very clearly and the lamp is brightly visible even from the street 60 feet away. I made measurements of light output versus voltage for six different types of LED lamps that were available to me.