receiver for parabolic dish solar concentrator

[nic]

Pics and video from the first tests of our dish. We wanted to locate exactly where the focal point is.
After 2-3 seconds, the wood starts to burn... better wear good goggles!

pic_dish_2.jpgpic_dish.jpg

a short video is available here: http://www.nicolascretton.ch/video_dish.mp4

[nic]

Spot on Nic, I'd do the same. Apologies in advance for the plethora of questions and the scattered manner that they appear.. Are you using the Uno or Due Arduino? Oh and I saw your receiver coil too, looks a hefty bit of kit.Are you planning to house it in something to reduce heat losses or is it going to remain open? Currently I'm calculating whether to use a DC motor or an actuator to move my dish but can't quite decide which is best. Given that the Arduino output volts/amps are small are you using that to power your actuators directly?? I suspect not but don't want to preempt your response. And finally,are you in Italy by the way? You can hopefully PM me that bit if you don't want to mention it on a forum wide basis.. I can't send PM's to anyone but a few, escapes me as to why but it's irritating nonetheless.

For the receiver, you might want to check out the very interesting research of K. S. Reddy (India), in particular the one published in the National Workshop, "SOLAR Thermal Power Generation", April 28, 2008, Mumbai. We wanted to construct a receiver similar to his "modified cavity with insulation", but we opted at the end for a simpler cylindrical configuration (still with insulation).

We use Arduino Uno. Of course, because of its low voltage and current capabilities, Arduino does not drive directly the actuators, but commands relays that close or open to let the necessary current flow to the actuators. The complete circuit will be published together with the final report.

We are not in Italy, but in Ticino, the Italian part of Switzerland. Check out my webpage http://www.nicolascretton.ch for further details on our school, my teaching and other maturity thesis in renewable energy and astronomy.

receiver_modified_cavity.jpg

[ReggieThe Dog]

well, sort of... We were thinking, in case of blackout, to tell arduino to immediately move to a safe position and not to track anymore (even if there is still power in the ups to continue the tracking for a few minutes). Maybe we can tell arduino, when the current is back on, to resume tracking. We'll see if we can program that sort of thing.

Spot on Nic, I'd do the same. Apologies in advance for the plethora of questions and the scattered manner that they appear.. Are you using the Uno or Due Arduino? Oh and I saw your receiver coil too, looks a hefty bit of kit.Are you planning to house it in something to reduce heat losses or is it going to remain open? Currently I'm calculating whether to use a DC motor or an actuator to move my dish but can't quite decide which is best. Given that the Arduino output volts/amps are small are you using that to power your actuators directly?? I suspect not but don't want to preempt your response. And finally,are you in Italy by the way? You can hopefully PM me that bit if you don't want to mention it on a forum wide basis.. I can't send PM's to anyone but a few, escapes me as to why but it's irritating nonetheless.

[nic]

I hope you also use a signal from the UPS to tell the Arduino to move the dish to a safe position when the UPS is near the end of its stored power.

well, sort of... We were thinking, in case of blackout, to tell arduino to immediately move to a safe position and not to track anymore (even if there is still power in the ups to continue the tracking for a few minutes). Maybe we can tell arduino, when the current is back on, to resume tracking. We'll see if we can program that sort of thing.

[inetdog]

Against power blackouts, we use an UPS for continuous power.

I hope you also use a signal from the UPS to tell the Arduino to move the dish to a safe position when the UPS is near the end of its stored power.

[nic]

Hi Nic, I'm new to this forum, just joined today, but just wondering how the experiment is going and wondered if you cared to exchange info/research. I am currently designing a 2.5m paraboloid and plan to build from scratch. Naturally there are many challenges to overcome with the receiver being a key one. I do have some info on receivers but not much, unless of course you want to spend lots of money on ceramic bodied heads etc... The dish I plan to build will have a focal length of 156.25 and the dish itself will be of a matrix type frame construction covered with bands of sheet metal and then finished off with 3M's 1100 solar Mirror film. Can I ask what you are using to track the sun and if you have any temperature monitoring at the FP?

We will post a link to the the final document (that contains all the details) in a few months. The text is in Italian but there are plenty of pictures and the technical terms are relatively easy to understand. To answer the above questions, we perform tracking with Arduino that pilots 2 linear actuators. And yes, we have a temperature monitoring inside the receiver for safety: e.g., if the pump stops, it will get very hot and thanks to this sensor, Arduino will know that it has to move the dish away from the Sun. Against power blackouts, we use an UPS for continuous power.

[ReggieThe Dog]

Request for info exchange

thanks to all for the safety warnings. We will use appropriate goggles and be careful.
We have included temperature sensors and an UPS in case of a blackout.

About the receiver, we could not find any on the market, so we built one (picture attached) with
a copper tube (painted black) and isolated (not seen on the picture).

As soon as the electronic is ready, we will start testing. [ATTACH=CONFIG]2533[/ATTACH]

Hi Nic, I'm new to this forum, just joined today, but just wondering how the experiment is going and wondered if you cared to exchange info/research. I am currently designing a 2.5m paraboloid and plan to build from scratch. Naturally there are many challenges to overcome with the receiver being a key one. I do have some info on receivers but not much, unless of course you want to spend lots of money on ceramic bodied heads etc... The dish I plan to build will have a focal length of 156.25 and the dish itself will be of a matrix type frame construction covered with bands of sheet metal and then finished off with 3M's 1100 solar Mirror film. Can I ask what you are using to track the sun and if you have any temperature monitoring at the FP?

[randomness]

Here's a quick one done with SketchUp [ATTACH=CONFIG]2551[/ATTACH]
Just a concept drawing, the coil could be multi-layer, I.E. enter the bottom, spiral up near center then spiral down near the outside, or up, do 180, down, 180, up, down... The cone helps collect the light/energy. After placing the coil in the can then fill with cement. Hope this helps.

Thanks, but I would like to know how to use it. I suppose we fill the cone with water, and put the focus directly on water (the cone)? But I don't understand the use of cement - the sunlight can't penetrate it and it's a good conductor of heat.

[russ]

Hope this helps.

This is crazy - don't even bother to tell us how it goes.

[liderbug]

Coffee can receiver

I'm interested in building receiver too. Where can I get more information?
The idea about coffee can and copper coil sounds interesting, I would like to see some pictures and more information.
Thanks!

Here's a quick one done with SketchUp receiver.jpg
Just a concept drawing, the coil could be multi-layer, I.E. enter the bottom, spiral up near center then spiral down near the outside, or up, do 180, down, 180, up, down... The cone helps collect the light/energy. After placing the coil in the can then fill with cement. Hope this helps.

[russ]

Sorry but this is going off the deep end - some of these points/methods are close to loony and unsafe.

This is not the type of thing we are interested in telling people.

I understand the desire to do something on the cheap but there are limits.

[randomness]

Actually I was thinking simply to wrap copper tube around a black bottle from beer. Will this work?
Also, can someone please explain why a copper coil helps? Isn't it better and simpler using a black glass bottle alone to heat water?

[randomness]

I'm interested in building receiver too. Where can I get more information?
The idea about coffee can and copper coil sounds interesting, I would like to see some pictures and more information.
Thanks!

[Hammer]

I'm thinking of doing something like this for fun when I move, but my neighbors are so close to my house down there. I do believe my father-in-law already has a parabolic dish, just not the mirrors.

I hope nic is OK and not cooking himself I would like to know how his dish worked. Someplace on here there is talk about another dish and a guy was wondering about using it for cooking dinner. Are you going to make a container and do the same thing but use sand as a heat medium?

[FunGas]

If there are any survivors please tell us all about the experiment.

haha - I built an array of 30, 1 inch mirrors all reflecting to the same point, it was enough to melt lead, this was in London.
Such a large parabolic reflector could indeed be dangerous - wear sunglasses

the mkII was a lot bigger and heavier