Has anyone done anything making prisims or reflectors small enough to be oriented electronically like a LCD display? It would lay flat on the roof and require no electric motors linkages and other nonsense.
At first it sounds way too expensive but there may be short cuts.
Bret Cahill
Yes. Some projection TVs work with a MEMS device that is essentially a bunch of mirrors mounted on tiny diving boards. Try this link for how they work:
1) Visit your big screen TV emporium. Micro-mirror arrays are a display tactic. 2) Dust and corrosion; reflectance spectrum; large area array fabrication cost; energy cost to position and hold the mirrors. Ditto cm mirrors and macro-actuators. The world is a dirty, wet, abrasive place. 3) Birds - excrement and mid-air blinding or incineration.
-- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/qz3.pdf
There are chips with about a million mirrors for xvga projectors.
Hi all;
I lost my reference to a flat heliostat array that was made by sandwiching plastic balls between two sheets of transparent plastic.
The balls were made from clear plastic hemispheres. When assembled a reflector is installed between the ball halves.
It operated by shifting the front pane which roles the balls simultaneously. Effectively this forms a heliostat.
Anyone have the reference?
This sounds kind of what Bret is looking for.
Duane
-- Home of the $35 Solar Tracker Receiver
What securely couples the balls to the transparent top plate so they cooperatively roll? If the surfaces are transparent and non-scattering they must be smooth. Smooth optically homogeneous surfaces don't grab - or they REALLy do, as in a pair of quartz optical flats placed face to face. Oh yeah... Newton's rings at each contact point. Plus wear. Plus inevitable gaps for close-packed spheres in 2-D. Creep?
How does one avoid optical distortion through the curved sphere top piece? How hot does your little greenhouse get internally in full summer sun?
-- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/qz3.pdf
One advantage of using video technology is when a bird tries to fly overhead, he can be located on radar and rapidly increasing numbers of mirrors are diverted from the receiver to the bird, say + 10 watts/
0.05 seconds, until the bird realizes he needs to find another place to relieve himself.You never hear much about cleaning reflectors but that may be the biggest problem of all.
Bret Cahill
That may be more expensive than silicon photovoltaic.
Bret Cahill
Maybe just the top sheet needs to be clear.
< The balls were made from clear plastic hemispheres. < When assembled a reflector is installed between the < ball halves.The index of refraction of the ball plastic doesn't play any role?
You don't really need a solid ball. A wire frame could work just as good ot better. Ditto for the pane.
< It operated by shifting the front pane which roles < the balls simultaneously. Effectively this forms a < heliostat.So once the mirrors are focused at the receiver for one position of the sun, they can always be focused on the receiver regardless of the sun's position simply by rotating every mirror the same angle.
What about rotating the pane itself?
< Anyone have the reference? < This sounds kind of what Bret is looking for.I'm looking for 20 cents/watt at 600 F.
Bret Cahill
Hello Bret Cahill, I had a similar idea some time back, about using milli or micro mirrors to concentrate sunlight at a place to be used for energy generation .
I have a post on my blogsite which explains what I thought with some pictures. You are invited to see and provide feedback on the concept. This link will take you directly to the post;
Surely an array of small reflectors could be put under a sheet of glass sealed in with some relatively inert gas - cleaning the glass is obviously less a problem with flat sheets. The other way to go (and is already in use in concentrator arrays) is fresnel type lenses but without individual elements shifting to track the sun, but presumably the same essential mechanisms could be used to make them trackable. Still all these ideas will be moot once a low cost solar cell is developed and hits the market. These ideas may have specialist applications but concentrators are only needed as long as high cell prices mean that reflectors and concentrators can give overall cost reductions - pursuing them as a goal ahead of pursuing cheaper forms of PV seems wasteful, unless there is some reason to believe significant cost reductions are otherwise impossible. With new nano materials emerging all the time and many having photoelectrical properties the possibility seems better than ever that we will see a low cost alternative to mono and poly crystalline silicon emerge . I tend to think fixed fresnel style lenses could have a place on roofs with less than ideal angles to the sun yet even there a flat plate panel might be sufficient, dependent on just how low the cost of PV can get and how efficient they are with less than full sunshine. Ken
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