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Reflecting sunlight for solar gain - Page 5

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Posted by vern on June 12, 2007, 1:52 am
 

On  9-Jun-2007, david.williams@bayman.org (David Williams) wrote:


I like that backlash measurement routine.  Have to watch for hysteresis in
switches but I'm sure you know that.



That's how it should be - seeing who can do it the cheapest.



Not concave.  Just those 1"x1" mirrors you can buy all over.  Each is on a 3
point mount so they can be individually aimed.



Yep, been to Red Rock, the canyon and the site.  Wish I had as much sun as
Vegas.  I'm near Buffalo.  What I'm doing making solar collectors here, I
have no idea.

Vern

Posted by vern on June 12, 2007, 2:09 am
 

On  9-Jun-2007, david.williams@bayman.org (David Williams) wrote:


Complicated shooting it in a window north-east of the heliostat. Yep, my
shop window is to the south of the heliostat.  Not only that but I have
about 4 acres to the north of the shop with a gently rising hill.  Just
about made to order for a heliostat field.  However in this area (near
Buffalo) we have very little sun in the winter when we could use some thermo
energy.  I pay only about $.04/kwh so making electricity isn't economical
either.  But it sure is fun and it does feel right.  Maybe someday we'll get
smart and do it like Europe where many countries will guarentee to buy all
the electricity you can make at a very good rate.  I heard Germany pays
$.50/kwh but that seems high.

Vern

Posted by vern on June 12, 2007, 2:24 am
 
On  9-Jun-2007, david.williams@bayman.org (David Williams) wrote:


That's the big problem right now - how to make the sensors around the target
so that they discriminate individual heliostats. I had thought of cameras
and did some experimenting with web cams in the middle of my window.  I knew
it was not the best place to put a chunk of plastic but they were old ones I
had laying around.  Took about 4 months to melt the first one and only about
2 days to cook the second one.  I think you could probably make cameras
mounted around the target work but it would be tricky with them so close to
the heat and trying to reflect light from small mirrors around the target to
the cameras (in a cooler spot) seems even trickier.  I might end up with a
system like yours yet!

Vern

Posted by Morris Dovey on June 12, 2007, 2:47 am
 vern@nothing.com wrote:
| On  9-Jun-2007, david.williams@bayman.org (David Williams) wrote:

|| Maybe you should plan big, and design a heliostat "field", with a
|| whole lot of them all aimed at a single target, which maybe
|| contains a boiler to drive a steam engine. The mirrors will have
|| to be individually controlled, so if you're still using l;ight
|| sensors, you will have to figure out how to make each sensor
|| respond only to light from its own mirror, not from the others. I
|| guess the sensors will have to be very directional.
|
| That's the big problem right now - how to make the sensors around
| the target so that they discriminate individual heliostats. I had
| thought of cameras and did some experimenting with web cams in the
| middle of my window.  I knew it was not the best place to put a
| chunk of plastic but they were old ones I had laying around.  Took
| about 4 months to melt the first one and only about 2 days to cook
| the second one.  I think you could probably make cameras mounted
| around the target work but it would be tricky with them so close to
| the heat and trying to reflect light from small mirrors around the
| target to the cameras (in a cooler spot) seems even trickier.  I
| might end up with a system like yours yet!

This begins to sound like fun. How about a one-pixel camera: a
phototransistor mounted in a (az-el steerable) skinny tube _not_
located in the target area. The tube can be aimed at each mirror in
the field to allow calibrating each mirror's aiming base (one at a
time so as to not fry the phototransistor), and as each mirror's
aiming is calibrated, it is re-aimed at the collection target.

The phototransistor tube itself can perhaps be initially calibrated
against a blinkable light whose position is fixed relative to all of
the mirrors.

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/



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