Oh Yeah!! I hear you cry … easy for you to say and you must be some sort of hippy to get involved in Eco energy …. well you might well be right but you cannot deny that we should all be considering the impact that carbon fuel usage is having upon our lives … nor can you deny that you abhor paying extortionate utility bills!! So if you can make some little change is this not at least worth thinking about or taking some action?
OK so that’s the “Save the Planet” lecture over and I can now tell you I actually had great fun exploring this whole alternative energy subject (and am now hooked so the exploration continues…have you even heard of CFM or PCM before?..me neither!) Needless to say the internet and youtube specifically, had the greatest influence upon my thoughts and decisions…although like any other wannabe inventor/developers I did have to do some things “My way” just to feel I wasn’t JUST copying someone else’s idea!
Incidentally…I don’t consider myself a “Geek” in any way but I do have a massive curiosity for many things which, when I am sober, can fill my head to the point of distraction; when I’m less than sober there are many wild plans considered and hatched!! This project I embarked upon (calling it a project sounds grand but then I was a project manager before retiring…the reality is that this was a simple little build and not a complicated project so don’t be put off trying something similar for yourself)
Where to start?
Well I do hope that you may get some useful guidance from this article of course but there is a body of people like myself with a smattering of Geeks thrown in for good measure (I don’t even think they would take that as anything other than a complement) who live to help others with respect to solar energy and every conceivable challenge it might throw up. The group is called Simply Solar and the first thing you should do following reading this article is to introduce yourself to them (SimplySolar@yahoogroups.com) or at their new forum and explain what you would like to achieve … and then trust me; the answers to questions will come thick and fast … this is a really special forum who really just want to improve designs and trial all different concepts and so every new member to the forum is a potential wealth of knowledge to be encouraged and coached by the team. Now I may be sounding like a geek myself again but Solar energy does touch a soft spot for me and these guys represent the best there are in this field so do not be afraid to use and get to know them.
Just a little background:
My son Paul, who designed and runs this website, was with me in Greece when we lived on an Eco farm (Kentavros farm) for 2 months last year where we relied SOLELY upon solar energy both for the hot water and the electric. When I then moved to Crete and Cyprus, I became interested in the solar heaters on the roofs. Finally I conducted a recent 2 month housesitting assignment in Southern Italy (The title picture is looking out of the villa at the setting sun) where the Villa owner had solar heated water… unbeknown to him his builders had sadly configured the system completely wrong and he actually had the gas boiler/furnace heating the solar water panel (yes the panel was actually hot at night when the outside temperature was close to zero!!).
I currently have plans in to develop a ram-shackled barn into a residence and you can imagine how my brain is in overdrive considering what can and cannot be achieved by way of renewable or sustainable energy production on this site …within the increasingly stringent constraints of the local building authorities of course. THATS why I have moved from simply contemplating to implementing just one of those many thoughts and make a prototype solar air source at minimum cost.
Mention Solar and most folks think PV (photo voltaic) but this experiment is dealing only with heating the air using the sun and does not generate any electricity just hot air.
So back in the UK, in S Wales, I set about building a small panel and had to decide how best and most cost effectively I could accomplish this. At the time I was engaged in doing some refurbishment of the property I am living in so did have some timber, etc to hand but the question of the glazing for the build was an issue. Looking around I determined it might be an idea to utilise one of the glazed patio/garage doors in situ as the glazing aspect of the project and so this became one of the determining factors in the build…the other was the collector and I had not yet found a suitable item to utilise.
If you are totally new to Solar energy then I am fully aware that the last sentence simply passed over your head…I apologise…let me now tell you what the hell we are trying to achieve and the steps needed to accomplish the task.
- We want to use the energy produced by the sun to provide free sustainable heat
- We need therefore, to convert that energy somehow to provide “usable” heat
- We need a means by which we can “gather” or “capture” heat from the sun
- We need to prevent the captured heat from dissipating before we can use it
- We then need to move the heat into the area we want to heat
- We need to consider the positioning of this “Solar Panel” so that we collect as much winter sunshine as possible (we simply do not need the panels to the same extent in the summer months)
All of the above points can be achieved by building a simple insulated box which houses an element which we shall call the “collector” and this is enclosed in this box behind glazing which is pointing directly to the sun. The sun passes through the glazing, hits the collector which is usually painted matt black to absorb maximum heat. There is an inlet (usually at the bottom) and an outlet (usually at the top because hot air rises) and a fan to push the air into and around the collector the collector then imparts it’s heat on the air and it passes by fan into the area you want to heat. ….And that’s it….just like a hair-dryer but using the power of the sun rather than electricity.
If you engage with Simply Solar you will soon become aware that there are many prototype and even commercially produced designs to consider but for the sake of this short article I have decided to build a solar panel using a metal collector rather than some other designs which use different layered screens (my next project most likely).
The Collector I used is an old sheet of galvanised corrugated metal which I found in the disused, dilapidated barn I eventually wish to convert, and the housing (box) has been made from 15mm plywood with 1″ polystyrene insulation covered in reflective foil. The air is “encouraged” into the solar oven by a “push me pull me” arrangement of computer fans in the input and output but sadly I already know that these are insufficient to gain the required airflow through the box to give meaningful heat output.
It is best to have the air in the insulated box for as long as possible so that it has ample opportunity to build up maximum heat from the collector. One way to do this is to force the air along a snake like path through the collector (up one channel and down the other etc) in order to give the air sufficient time to heat up before being spat out at the business end!!
Relying upon natural convection and hot air rising then the collector (on our first sunny day in almost 2 months in February!!) has been registering more than 70 degrees Centigrade at our output. When I switched on the computer fans they increased the airflow (marginally) but the temperature in the outlet only experienced about 6 degrees drop…still pretty good considering the pool outside was still frozen.
To test the system with more air flow I then connected up my [do action=”amazon-uk” search=”HVLP (High Volume Low Pressure) paint-sprayer” linkname=”HVLP (High Volume Low Pressure) paint-sprayer” amazon=”http://www.amazon.co.uk/gp/search?ie=UTF8&camp=1634&creative=6738″ affcode=”livefree-21″]HVLP (High Volume Low Pressure) paint-sprayer[/do] pump to the inlet in order to get some real throughput….yep mission accomplished…hot air flying out but at what cost to the temperature?
Well encouragingly only about 10 degrees drop from 77 to 65 ish which is still pretty good I thought. (the HVLP pump will be replaced by a 12v solar powered fan with sufficient flow rate to make a difference and be powered by the sun to boot)
Building the box is a simple task but just needs a little planning to ensure all component parts are going to fit together. I simply used a circular saw to rip cut the four sides so that these could be glued and screwed into the rectangular frame. The backing was then screwed in place and that was the box done.
A critical component is the type of glazing used; you can use twin or triwalled polycarbonate sheeting, perspex, corrugated perspex, single glass glazing or even double glazing if available as a recycled acquisition.
We then need to insulate the box to prevent the captured and heated air from escaping and not being directed to where we need it. This can be done in many different ways but the easiest (not the cheapest though) way is to use easily cut foil backed compressed foam boards which are available from any builders merchant or DIY centre. I used a cheaper [do action=”amazon-uk” search=”polystyrene board” linkname=”polystyrene board” amazon=”http://www.amazon.co.uk/gp/search?ie=UTF8&camp=1634&creative=6738″ affcode=”livefree-21″]polystyrene board[/do] which I then covered in tin foil to reflect any heat back into the box. This is all simple to shape using a craft knife but make sure it is really sharp to get nice clean edges without too many polystyrene balls flooding your work area!
The collector needed in my case to be secured to the box through the polystyrene because it was really quite heavy (a lighter piece of aluminium would be much easier to handle and equally efficient). I needed to ensure the collector was secured and there was virtually a seal with the insulation to provide me with channels through the corrugations in the galvanised panel. Once secured I needed to craft a mechanism to take the air flow from one channel and feed it down the other and this did require a few carpentry skills. If you use aluminium downspouts or similar then you will not have the same problems that I did on this “one off” build.
With the box built and insulated, the collector panel sprayed with [do action=”amazon-uk” search=”heat resistant paint” linkname=”heat resistant matt black paint” amazon=”http://www.amazon.co.uk/gp/search?ie=UTF8&camp=1634&creative=6738″ affcode=”livefree-21″]heat resistant matt black paint[/do] and secured, the air flow worked out it was time to cut the holes for the input and output to correspond to the position of the air channels.
I cut the holes with a jigsaw because I did not have a hole saw big enough…once cut I screwed two computer cooling fans into place … pushing air in, on the inlet and sucking it out, on the outlet.
I then sealed the airflow compartments at the top and bottom of the box and it was time to offer the beast up to the window I had chosen to host this parasitic masterpiece. It would have been so much easier to screw a sheet of polycarbonate to the face of the box and create a free standing solar panel but needs must and so the panel was secured to the patio door by sitting it on a prepositioned piece of timber at the bottom and an angle bracket at the top. It was a really good fit but to make it air tight around the edges I used decorators caulk (this is easier than silicon and can be removed much easier too since this was only a prototype) Obviously the door is not able to be adjusted in position and so I am stuck with the slightly “off tune” collector but for test purposes this was a good compromise.
Final stage was to drill a small hole into the output cavity to house the [do action=”amazon-uk” search=”Digital LCD Thermometer Food Temperature Sensor Probe” linkname=”digital thermometer” amazon=”http://www.amazon.co.uk/gp/search?ie=UTF8&camp=1634&creative=6738″ affcode=”livefree-21″]digital thermometer[/do] I had purchased on ebay…this is a handy oven/food preparation sensor with a long probe which can fit into the small hole without affecting performance.
Really final stage….this took nearly 2 months….wait for the sun.
When the sun finally did arrive I was more than pleased with the results. It was minus 1 centigrade and I was generating between 50 degrees and 77 degrees centigrade output and when I ran the HVLP fan I only witnessed about 10 degrees drop so I can now search for the correct size of fan to produce consistent output. This is measured in CFM which is Cubic Feet per Minute and lets you know how much hot air you are producing…not nearly as much as I have in this windy article I guess though!! 🙂
-1 degree to +77 degree centigrade….result!!
I can only hope that this might inspire one or two others to consider their environment and look to the sun for inspiration on ways to make lives more considerate to the planet.
Any comments are welcome.