DIY solar panels, Part I

I have been working on this for most of the summer.  The problem with solar energy systems is that they are expensive.  There is no doubt that a photovoltaic (solar electric) panel will save energy and pay for itself in time, however, the initial outlay of money to purchase and install that panel is more than most homeowner’s can afford.  Solar thermal systems are likewise good investments, however, there associated systems are complex and need to be carefully designed and installed so that they function correctly.

What if someone could design a solar collector that can be easily built and installed by the average do it yourselfer.  This is the idea that I had and I think I may have something.

Here are a few design benchmarks:

  1. That solar system would need to be fabricated on site with standard power tools.
  2. It should be constructed of material readily available at most home improvement stores and the like.
  3. The system should be simple and easy to understand and troubleshoot.
  4. It should be simple enough to construct that anyone with basic carpentry and metal working skills can build it and install it.
  5. It should be efficient and relatively inexpensive, paying for itself in one year.

Those are the basic ideas I had and I believe I met most of them with my design.  What I was going for was something that would produce heat during the winter time and be optimized for cold snowy locations.

This solar collector is used to heat air, circulating air over a collector plate and returning it to the conditioned space.  Air heating panels are simpler to construct than water heating panels, their downside is that there is no storage capacity associated with them.  In other words, they work great when the sun is shining, but will not produce any heat at night.  They are suplimental heaters in most cases and cannot replace a central heating system.  That being the case, they can still save a significate amount of energy.

The main collector surface is made from aluminum drink cans.  The cans have the tops cut off and are stacked horizontally like this:

horizontal can solar collector

horizontal can solar collector

This arrangement is more work and requires more materials but it has several advantages over other designs:

  1. Each can becomes a mini solar receiver similar to solar receivers used on large concentrated solar systems.
  2. The array of receivers gathers energy more effectively because there is less reflected energy than an ordinary flat plate collector.  Once the energy strikes the collector surface, it is reflected down into the cans where the convex bottom aids in absorption.
  3. If mounted on a vertical south facing wall in front of a reflective surface such as a snow field or dry sand, the array will gather much more solar energy due to the increased insolation area.
  4. Aluminum is an excellent conductor of heat, thus the heat will move to the back of the collector plate, which will be cooled by forced air.

The main idea here is to make it simple yet effective.  Aside from the collector, a 250-300 CFM DC fan and a PV panel round out the system.  A small “snap disk” thermal fan switch turns the fan on and off depending on the collector temperature.

Part II will discuss tools and materials.  I expect the system to cost about $400-450 to build.  The most expensive item is the PV panel, which can be substituted with an AC wall transformer.

Part III will be a sysnopsis of my own system.

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9 comments to DIY solar panels, Part I

  • David Burkhart

    Paul,
    This concept is an excellent one that I assisted my father in building in the mid 1970′s. The pitch of the panel angle was matched for the coldest of months in Ohio (February- based on a 40 degree Lat.), and was built with a triangular matched angle back. Inside, cement blocks, painted flat black to seal the porous surfaces were strategically stacked to ‘fill’ the entire enclosure. This provided an average 40% cost savings to the church, of which he was pastor for nearly 40 years. New pastor tore it down last year. With the price of NG this year, he will undoubtedly wish for that free energy again. As F.G. would say, “Stupid is, as Stupid does”…lol. Funny thing is, my dad wasn’t a tree-hugger, but is the most conservative of men, and still lives it through leadership and example. We picked up aluminum beer cans from the ditches in the early 70′s to raise money for a new church building. The best cans (12 oz.) were cut off one-third of the way from the bottom, as this gave us the highest output of BTUs. per sq. ft. I plan to build a few of these collectors this fall, as I want to heat the garage, and may use for a way to add heat through basement windows. I will post some pics of old solar collector and new ones as we proceed.

  • Dave,
    Thanks for the feedback. Your story of your father and his church is great, I enjoy hearing things like that.

    It seems to me like it is a good design. I was reading about honeycomb absorber plates and I also read an article in Mother Earth News about using soda cans for solar collectors. Most people simply stack the cans on end and blow air through them.

    I am getting ready to post part II this week. I am going to follow up with some performance data once I get the panels mounted.

  • Very interesting! Very interesting indeed. I’m going to follow this closely… and perhaps USE it!

  • David Burkhart

    I believe I can get a few photos from my folks this weekend and will attempt to either post them, or will post them on a website I have running for another subject.
    The use of Glauber’s Salt was recently recommended by dad, though I am unsure of the storage vessel, etc. This solid salt turns to a liquid at 90-110 degrees F and is the most efficient of storage mediums for air-convection-type systems.

  • Perry P.

    Paul: Sorry, I misread your article initially and thought it pertained to a water-heating device. Do you have any thoughts as to whether your aluminum can collectors would be helpful in a water-heating system constructed by running inexpensive black poly tubing transversely through the cans near convex end, and also between cans, with a black absorptive background? I just picked up a cheap traditional solar thermal panel which has rows of thin copper pipe against a black plastic background panel covered by a somewhat translucent surface plastic panel, and your cans would seem to be an improvement. Any idea how much better are your cans at capturing solar heat than a flat surface (at a fixed location during the winter season in North America?) Thanks.

    Perry

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  • solar panel Morgane

    Solar panels provide clean and renewable energy. I use one, and I’m really happy with it.

  • winckel

    hy
    good idea
    did you have some pictures from you panel

    thanks

    eric from france

  • i find anything thats saves money to be great, i am working on building one of these soda can heaters and then putting a step by step instruction on my web site for all to see and use.
    I am gathering all the parts needed to build one and i am looking for a snap disc at the minute to make the system automatic but i am figuring out how to store some of the heat for night use with a small fan.
    i am going to build one and post a break down of cost for all to see and what parts were used.
    It needs to be real cheap so all can build one if interested.
    the concept is great and there are many people on you tube that have built them.
    thanks,
    mark.

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