receiver for parabolic dish solar concentrator

[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!

[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?

[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.

[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]

Hope this helps.

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

[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.

[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?

[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.

[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]

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.

[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]

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

[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

[ReggieThe Dog]

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!

[ATTACH=CONFIG]2577[/ATTACH][ATTACH=CONFIG]2578[/ATTACH]

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

Nic, Thanks for sharing. I hope to be at the same stage as you guys are in a month or two. Slovenia is proving both difficult and expensive for the right supplies though. We live in the mountains and have some very clear winter sky so I'm hoping that my 2.5m dish will provide us with enough heat for water, heating and a source of distillation/pasturisation. Looking forward to reading your report with much interest. I also have the receiver slide that you shared and was thinking of using this http://shop.vitcas.com/ceramic-fibre...tion-197-p.asp as an insulation material. It's a little expensive but more than good enough for the job. at least that will minimise any heat losses.

[nic]

Nic, Thanks for sharing. I hope to be at the same stage as you guys are in a month or two. Slovenia is proving both difficult and expensive for the right supplies though. We live in the mountains and have some very clear winter sky so I'm hoping that my 2.5m dish will provide us with enough heat for water, heating and a source of distillation/pasturisation. Looking forward to reading your report with much interest. I also have the receiver slide that you shared and was thinking of using this http://shop.vitcas.com/ceramic-fibre...tion-197-p.asp as an insulation material. It's a little expensive but more than good enough for the job. at least that will minimise any heat losses.

Heating a house only with renewable energy is extremely difficult, unless your house is up to the best insulation standards. Let me explain why: Energy needs for heating can vary from 30-40 kWh/m2 (for the best insulated houses) to 200 kWh/m2 for "standard" houses from the 1970, when nobody cared about energy efficiency. These numbers are per year. Keep in mind that heating is the main source of energy consumption (roughly 80% of your total energy need). Check out the swiss Minergie standard for more specific info (http://www.minergie.ch/minergie_fr.html). For instance to attain 40 kWh/m2, your walls and roof need to be insulated with ~20-25 cm of the best insulating material with lambda around 0.035 W/mK to attain U=0.2 W/m2K, your windows need to be triple glass with Argon gas (U = 0.5-0.7 W/m2K), etc...

So with one 2.5 m dish (area = 4.9 m2), an installation efficiency of 0.7, in a sunny winter day (sun power = 1000 W/m2) and 5-6 hours of sun (very optimistic), you can hope to produce 17-20 kWh per day. You see that 3 winter months, all of them sunny, would provide at best 1800 kWh. If your house is 160 m2, it needs from 6400 kWh (minergie) to 32000 kWh (standard) per year !

Therfore you need to 1) insulate your house and change the windows, if not already done, and 2) install more antenna or solar panels. Nonetheless, going solar is in any case a good idea since it's clean energy, but you need to make careful calculations, to see where is best to invest your money (insulation, windows or panels).

A nice solution if you have a heat pump (with COP = 3) is to go for photovoltaic panels: the electricity produced at 20% efficiency, with a COP of 3, "becomes" 60% efficiency in thermal energy thanks to the heat pump, almost as good as thermal solar panels, but with the gain that during summer, photovoltaic still produce a lot of useful energy (electricity that you can sell throughout the grid), as opposed to the useless hot water produced by solar thermal panel in the summer (I'm only talking of hot water for heating, since hot water for the shower is only 15% of your energy needs).

Nic

minergie.jpg