The (giant) Solar Funnel solar cooker
by Vinay Gupta • April 13, 2009 • Hexayurt • 3 Comments
(thanks for the pic, Jonathan)
At the Maker Faire Newcastle, we made a new kind of Solar Funnel solar cooker. The design is very simple but very effective: take a 4×8 sheet of thin corrugated plastic (2mm is probably ideal, we used a light grade of 4mm) and cover one side with ordinary tinfoil using glue.
Roll it up into a cone, with about a 45 degree angle, tape into place, and cook. Even in Newcastle in March we got a probe up to 97C and would almost certainly have boiled water if the sun hadn’t gone in.
Here is a picture of the solar funnel that shows the shape better, and two more.
In terms of power output, it has roughly 1 square meter of collection surface, maybe a little more, so it’s got a maximum output of about 1kw – not bad, that’s about 2/3 of a domestic kettle. In practice expect about half that output in the UK – still very workable.
Cost, in mass production, would probably be two or three dollars a unit. But it needs some kind of stand to keep it pointed at the sun – probably as simple as a wire curve that one pushes into the ground. I think this has some potential.
Looks very interesting. I had never thought of using corrugated plastic. I built a funnel out of 2×4 insulation that looks like a car window sunblocker. I might try this design. I’d like to know if you get hotter than 97 degrees. Thanks a lot.
Bill
Hello Vinay,
Just browsing around, having not looked at your site for some time. I have seen the basic idea used before as an “appropriate tech” solution to deforestation in sub-saharan Africa, although this used a parabolic reflector, which would be anything but basic. It needs to be simplified.
Your idea could be the step change to make it commercially realisable, if it can acheive the right level of performance while being based around a flat sheet component. However, if this flat sheet could itself be collapsed, rolled up, then unrolled and re-assembled into the collector shape – and have this done over and over again – then you have a PRODUCT! Have you tried sticking aluminium foil to a camping mat, purely by way of experiment? Just a thought.
Of course, as you mention there is not only the problem of how to support it, but also to contain and support the food and its pot or pan while the sun is doing the cooking. Some kind of tripod might be useful, from which to hang a pot, although asking the tri-bike to perform that function as well might be stretching the concept too far.
Hope to see you soon at some Riversimple / 40 Fires event or other.
Best wishes,
Jonny.
Great work.! I have made slightly smaller one for home use—about half this size. Proper support is essential, particularly for a windy day. Can we use a thin Aluminum sheet such as the litho-printing plates which are easily available and may be free of cost?