Stationary Solar

Hi Chris,

Would this track have to use more than 1 axis?

I.e. if the object is on the ground, to "follow the sun" the
lense would have to both rise up, and travel, along the track?

Correct me if I'm wrong?

jt.

yes I think so. azimuth?

You only need 1 axis parallel to the earth's axis, as in a telescope equatorial mount.

Yes, I think you're right, (thinking about it) thank you.

Just one track, at an angle, should be able to "track" the sun.

I'm thinking of giving it a go - when I have finished the house repairs!

Many thanks.

jt

Yes dear,

The answer is yes, Fiber cables( hollow nanofiber tubes) can be deployed to bring collected sunlight to a fixed point on the ground as the collector tracks the sun.

As of now the situation is hypothetical as no where in the world is has been tried practically. Scientists have give a theoretical model similar to what seem to in your mind, to collect the Solar energy in space and direct it to a point on the earth to generaye power.

Dr N P Singh

Can fiber cables handle the heat?

The collector will be located on the ground and the object to be heated is less than 2 meters away.

Yes, we need to track the sun precisely. We are not trying to make power, just heat but lots of it.

MIT, Mass., developed a low cost bimetal element based tracking system that moved a parabolic mirror to track the sun keeping the focus on the mirror axis.

bioramani

My sons took the 4 large lens out of an old projector television and they shoot a small lazer thru it. It will burn a hole in paper really fast. Turning it to the sun will set dry grass on fire quickly.

the light tubes used to bring natural sunlight into the basement can turn a few corners with some loss of lumens. combine an array of these focused on a fresnel lens. this may be cheaper and simpler than tracking device, just collect from a larger area. a 1 meter square freznel lens will melt a hole in a penny.

Great Idea!!

Interesting variation on the idea of using heliostats.

A number of heliostats can be trained on a mirror which can be arranged to focus on the ground.

For large scale thermal solar and solar furnace use, heliostats are probably the cheapest and often the simplest arrangement.

Hi, try a look at www.redrok.com , a very nice site with loads of links to all the stuff you will ever need to track the sun.

I built a LED-tracker, it works a lot better than I suspected, and it is precise enough to focus a satelite dish within a degree or so.

The issue is the actuators, they seem costly/difficult to build/scrounge when cost is a matter. My best advise is to rotate an allthread with ballbearings slowly, it produces high torque and is firm when equipment is exposed to wind.

Good luck, and keep us posted, please!

regards, moe

Thanks for the information.

I'll post updates when they occur.

I did dripper trackers. One type just used a water clock. The other is the clock based dripper tracker.

You take apart a digital clock and replace the hour hand with a wheel. You attach a tiny pipe to a string attached to the gear. (weighs about 100 grams). As the string unwinds hour by hour, the pipe lowers and water drips from one bucket to another. Floats in the buckets turn you refector on equatorial mount. (If the floats are a fairly snug fit, it is amazingly stable)

The advantages of this method are, it is very cheap. and even a gale force wind will not damage your clock. I have not yet found the right clock (I have not looked very hard). If anyone else trys, it does not need a clock. Anything that produces slow precise linear or rotating movement will work.

A regular movement every 10 minutes would also work. (The drip pipe will even out the speed enough for most applications). I first suggested this tracking method a year ago.

Perhaps people only listen to bigshots? I have no idea why nobody else has tried it.

The webmaster put it on solarcooking.org almost immediately after I showed him the idea.

But nobody has acted on it.

Brian

Could you use the redrock tracker with my plastic 2 bucket dripper tracker iidea?

http://solarcooking.wikia.com/wiki/Tracking

I used a digital wall clock with an extremely weak motor. I made a wheel attached to the hourhand drive ring. All it had to do was let a small plastic tube lower slowly as string unwound from the clock. With the dish on equatorial mount and its focus on the axis, the clock provided the right movement

Now, if you used the redrock tracker to control the filling and emptying the buckets, you would not need anything expensive. You might need 3 or 4 buckets and you need a little pump to move the water.

The floats in the buckets are not directly connected to any electronics or delicate hardware so it makes it very resistant to damage. And if the floats are reasonably tight fitting it is amazingly resistant to wind buffering too.

Brian

Hi gaiatechnician...

"Could you use the redrock tracker with my plastic 2 bucket dripper tracker iidea?"

The redrok LED-tracker can control any small (12V) DC-motor, like the ones in auto-sprinkler pumps, pantry-pumps for boats etc. I'm not sure if the pump "pumps back" when polarity is reversed, the motor definitely goes backwards, but will the water go backwards too? That remains to be seen. And the "end-stop switch" must be some kind of float-switch, and there needs to be 2, one for each direction.

I personally prefer a mechanical solution, as you mention the string attached to the hour-handle on the digital clock, but the motor is weak. A small DC-motor from an old CD-drive (most likely there are 2 motors in every drive) could do the trick with the string. Attach a tube or wind the string a couple of times around the motors center-rod and you have your "drive".

Using water, there is evaporation and some tinkering to make the strings accurate and easy-going. You have to check on the process often, I presume. The solution with an allthread on ballbearings is very stable and applies same torque both ways. And with 2-axis tracking the setup is fully automatic.

But please provide some pictures if you got some.

Regards moe

Yeah, ok forget the clock. but use the led's to control the water levels in the buckets.

The buckets with their floats (like a piston) have a very powerful damping effect when the wind is blowing. Now, any mechanical direct attachment will take all the strain of the wind and will take a bad hit at that point. Think 40 or 50 mph winds. They will not damage the buckets but they can do a lot of damage to directly connected worm drives or gears.

Or maybe I am wrong on that point. I do not have decent pictures.

brian

Hi Brian, I see your point in the damping effect, but the floats has to be attached to whatever is hanging in the air and thus exposed to wind. The attachment has to be strong transferring forces to the floats. But the idea can work. And having the floats in barrols with a small hole for the attachment can make large movements and almost no evaporation. But I think there has to be 2 pumps, one for each direction. And there is the issue of freezing or using antifreeze (in my end of the world anyway).

Using allthread in proper dimensions (12 mm, 14 mm) and bearings welded to fixpoints can withstand some punishment. But it depends, of course, on the size of stuff exposed. Stuff larger than 3x3' requires larger allthread or custumbuilt spindles or hydraulics to take the forces from hurricanes. And engineering.

Regards, moe

Thank you. I think the ball park maximum size for diy instalations would be about 2 sq meters of reflector area. If you use the clock idea on equatorial mount, you need just one pump (for the end of the day to pump to the higher bucket ready to start again in the morning) and you would need something, either a cam or hand adjustment for the seasonal change (done biweekly) in the height of the suns arc across the sky). And maybe the fluid could be an oil or antifreeze?

I think someone else needs to try it, the floats in buckets gave much more stability than I expected.

Maybe in a school or college project.

Brian

Hi Brian, what I need from a system to track the sun, is that it needs to be automatic and self-adjusting and require no or very little maintenance, or else it will not be efficient, as it need to be in focus within a degree in both directions (horizon to zenith(90 degrees) and northeast to northwest (270 degrees)).

That is because I work in the daytime....

Now, my idea is a satelite dish focusing sun into a heatcollector (coils of coppertubing), and when temp. is above 80 deg. C the pump turns on by an electronic thermostat. If temp. in waterstorage is above 80deg. C too, then the dish is driven to parking position and power is saved and water not boiling. This demands some electronics, which I find amusing tinkering with. And gives some control over the heatcollection. I know, that the size of dish gives limited heat (60 cm diameter) but it doesnt take too much space.

Regards, moe

Scheffler solar kitchens work as you want. They adjust the shape of the mirror to account for seasonal changes in the sun's path.

You want the target stationary. Makes sense.

Interestingly, nobody seems to have made a parabolic mirror system where the mirror swings around a housing on the TARGET.

Always you see the support going to the BACK of the mirror. Why not the support going to the target, with the mirror attached to that support on some sort of gimbal?

Would the support have to be moved or changed once or twice a year as the parabolic dish changes its orbit? and would this be a big problem if it had to happen?

Brian

Hi Brian, thanks for the link, it was interesting to see other solutions, also the link to trinysol, where there was a mechanical clock-like solution to turn the dishes. Looks like scrap iron and bicycle parts, but I like the creative mind reusing stuff.

My project actually dont have a stationary target as it moves with the reflector. The target or the heatcollector is placed where the LNB used to sit. That requires flexible hoses to transport the water to the tank and back, which I have used.

You wrote:

Always you see the support going to the BACK of the mirror. Why not the support going to the target, with the mirror attached to that support on some sort of gimbal?

I dont understand your idea, maybe a drawing or else could clarify?

And I am aware that any installation requires some maintenance, mine, I suspect, minimum once a week checking waterlevel, tightness, easy movement of everything and filling in springtime and draining in the fall.

I havent had much, if any, time to work on my project for some months due to fixing up the house (new kitchen etc.), but I will soon be finished with that to relax with the hobbyproject.

Regards, moe

Thing is, I need way more heat than water system can ever provide. I need at least 1800F continuous heat.

I have just discovered that most metals don't like to be cherry red in an oxygen atmosphere. So, I now have to build a vacuum oven with glass walls so My metals won't break down.

Isn't this fun?

I am really awful at drawing. In your case, you can have flexible hoses and in schefflers case, he warps the parabolic dish to account for seasonal changes. I think if it were a mirror, it would be called a coelestat on the the equatorial axis and it would just need slight adjustment as the sun changes its path over the seasons. But a parabolic dish actually has to be warped to be maintained in the same place over a year and still point at a stationary target. I can link to a picture if that confuses people,

http://www.massmind.org/techref/other/solar/Scheffler.htm is ok but it does not show what happens as the seasons change. http://www.solare-bruecke.org/English/scheffler_e-Dateien/scheffler_e.htm is really good! An alternative to that is to have the target stationary. No flexable hoses needed. No warping of the parabolic dish needed either.

And attach a parabolic dish to the target. It swings on the target and is always opposite the sun. That means that your support for the target might get in the way as the dish rotates round it? I do not know.