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Posted by Morris Dovey on September 11, 2012, 9:24 pm
This is a follow-up to my (much earlier) request for suggestions/help
with developing a non-electric solar tracking device.

Daniel Connell (a Kiwi) has just announced completion of the set of six
open-source animated tutorials for building the SolarFlower, a
sun-powered sun-tracking high-temperature parabolic collector. It's
taken three years of work, and paves the way for people in developing
areas to avail themselves of solar thermal energy. You can see videos of
the prototype working at

(tracking timelapse),

(how it works) and

(tracking engine working)

The tutorials can be seen at www.solarflower.org and translation to
other languages is underway by volunteers all around the world.

Morris Dovey

Posted by mike on September 12, 2012, 2:56 am
On 9/11/2012 2:24 PM, Morris Dovey wrote:


I'd like to see the math on this one.
But first, the logic.
What resets it for the next day?
How is all this complexity better than a bimetallic strip
adjacent to the main heat collector pipe
that heats and unleashes the gear that lets a weight
drop slowly powering the machine?

If you have to reset it every night, might as well lift a weight
or wind a spring while you're at it.

How was the efficiency measured. 1kw/square meter is a nice number.
How much energy actually came out?
And how much would have come out if the whole width had been used
for collection and a much simpler motive force machine?

The sun doesn't take a circular path thru the sky.
How much efficiency is lost by only tracking one axis?
How often does the machine need to be repositioned to
get that much?

Posted by Morris Dovey on September 12, 2012, 5:31 am
 On 9/11/12 9:56 PM, mike wrote:

All good questions. This design has six important attributes:

[1] The how-to is available in ten languages - more on the way.
[2] It can be built using materials available everywhere.
[3] It can be built by folks with low-level skills.
[4] The most complex tool needed is a drill.
[5] It's very inexpensive.
[6] It works reliably.

It's a simple polar mount that needs to be manually reset to face toward
the east every day, with periodic manual elevation adjustments.

The main collector can be sized as needed (within reason) to achieve the
temperature and heat levels required for individual applications and

You're right that there's a Rube Goldberg aspect to it. Unfortunately,
those who /might/ have done better couldn't bother and/or didn't want to
get their hands dirty.

Morris Dovey

Posted by Jim Wilkins on September 12, 2012, 1:01 pm
If you meant me, my lot is so well shaded by 80'-100' oaks that no
suitable and safe collector location receives more than four hours of
direct sun. I put my solar panels and an ammeter on a cart and moved
them around the yard to search for the highest output, but nothing
significantly improved on leaving them on the rear deck pointed due


Posted by Morris Dovey on September 12, 2012, 5:25 pm
 On 9/12/12 8:01 AM, Jim Wilkins wrote:

I'm not singling out any individuals, nor will I - but I'm fairly
well-aware of readership for these the two newsgroups from activity on
my web site traceable to posts here. There are a lot more people reading
than posting, slightly more than half are in the US and Canada, and
bloody damn few (from anywhere) ever do more than feed off other
peoples' work.

I can't buy into the notion that /every/ American with a brain and two
hands has a yard full of 80' oaks, and I'm not proud that out of the
four or five dozen design/build contributors from all over the planet, I
was the only American.

One day later, in Kenya, the first end-user build is already underway.
Everyone who worked on the project is proud of that.

Morris Dovey

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