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Adaptation

Member

Registered: 2011-11-22

Posts: 42

Compound parabolic reflectors - earth based zmp solar concentrator

So I bought 50kw of Solyndra solar panels and I was thinking they would work great compound parabolic reflector.  I'm just wondering if I should have the parabolas focus to the center of the cylinder or not, I think a strong pinpoint of light will damage the solar cells so I was wondering if I should place it slightly out of the focal point or if I should make the parabolas slightly non parabolic. 

I plan on vacuum thermoforming  plastic then coating it with foil tape at first and maybe do some evaporative deposition of metal later.

Rxke

Member

From: Belgium

Registered: 2003-11-03

Posts: 3,669

Re: Compound parabolic reflectors - earth based zmp solar concentrator

50kw?? That's.... quite a lot!

You're going to use those for yourself or upgrade them by using parabolas to re-sell or something?

In any case, you have to make sure they don't get too hot or your efficiency goes down dramatically, even before they get damaged... Some places on earth parabolas+solar cells don't mix too well 

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,882

Re: Compound parabolic reflectors - earth based zmp solar concentrator

I have seen this compound reflector before on the tech groups on yahoo and it is intended for thermal liquid heat obsorbtion. It would damage the solar cells.

product like this one
http://www.gogreenheat.com/collector%20data%20sheet.htm
Compound Parabolic Hydronic Solar Collectors
Up to 30% more efficient than standard evacuated tube collectors

http://images.wikia.com/solarcooking/im … berger.pdf
COMPOUND PARABOLIC CONCENTRATORS FOR SOLAR WATER HEAT
PASTEURIZATION: NUMERICAL SIMULATION

Best one for all the calculations is at this site
http://www.powerfromthesun.net/Book/cha … ter09.html

Last edited by SpaceNut (2011-11-22 22:12:26)

Adaptation

Member

Registered: 2011-11-22

Posts: 42

Re: Compound parabolic reflectors - earth based zmp solar concentrator

I'm going to sell most of them as they are, I have them listed on ebay and plan on sell them at several other places.  But that doesn't mean I cant play with a few of them.  I've been thinking about compound solar concentrators for several years, I think I posted some stuff about them on this site but I think those posts are missing at the moment.  The Solyndra panels are rated at 85°C. I don't know if they will get too hot or not, I suppose that greatly depends on how large the concentrator are, I would like to triple the amount of power from each rod if I wanted to get 20x the power I would plan on jacketing the rods in another tube and circulating water through it.  What I am concerned with atm is localized heat like a linear beam hitting the rods instead of a more dispersed light across the 1" diameter tube.  I think if I build the concentrator by the book it will have problems but if I can pull it out of focus a bit I wont.  The stock I mill the termoformer mold is quite expensive and it takes a lot of time to mill so I would like to be fairly sure I have the design down before I get that far.

Last edited by Adaptation (2011-11-22 23:09:07)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,882

Re: Compound parabolic reflectors - earth based zmp solar concentrator

More on solar concentration

The motion of the sun is why we need to mount a system on an 2 axis system to follow the sun has to do with direct ray use at the focal point.

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,882

Re: Compound parabolic reflectors - earth based zmp solar concentrator

http://digitalcommons.calpoly.edu/cgi/v … ext=bmedsp
Design, Construction, and Test of a Miniature Parabolic Trough Solar Concentrator

https://wims.unice.fr/xiao/solar/diy-en.pdf
Manual making of a parabolic solar collector

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,882

Re: Compound parabolic reflectors - earth based zmp solar concentrator

HCPV Solar Parabolic Solar Concentrator Technology

We have talked about high temperature PV  cells in a few topics and this companies seems to be where we need solar to be.

Concentrating photovoltaic (CPV) technology uses optics such as lenses or curved mirrors to concentrate a large amount of sunlight onto a small area of solar photovoltaic (PV) cells to generate electricity. CPV multi-junction solar cell efficiencies of 46% are being reached compared to conventional solar power tower steam engine efficiency of 14% and average PV panel efficiency of 15%. Solartron works with CPV manufacturers and solar power plant project developers and provides a state-of-the-art parabolic solar concentrator for use with CPV multi-junction solar cell modules.

Making a dish seems to be probable.

So making solar concentrated would be possible

I think that due to low Martian gravity, and winds that are far less of a problem, it can be made from lighter materials.  This Spacenut also suggested.

But for the parabolic mirror, I am thinking Styrofoam, with a reflective coating.  The other surfaces may need a protective coating as well.
If Styrofoam, is not strong enough, then embed a wire mesh in it. 

This then being lighter, the supporting structures can also be lighter.  And of course that was obvious to the other members as well.

I am usually worried about the consumption of Copper and Aluminum, so I would like to avoid that when alternatives exist, or at least reduce the amount of consumption.  We do have Chromium, Iron, and Titanium available in the sand dune materials, and of course from other sources.

Sounds like we could do this...

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,169

Re: Compound parabolic reflectors - earth based zmp solar concentrator

Here is another member in good standing ...

Registered: 2011-11-22
Last post: 2013-04-06 17:36:05
Last visit: 2017-09-17 02:25:14

50kw?? That's.... quite a lot!

You're going to use those for yourself or upgrade them by using parabolas to re-sell or something?

In any case, you have to make sure they don't get too hot or your efficiency goes down dramatically, even before they get damaged... Some places on earth parabolas+solar cells don't mix too well 

The post above was entered in 2013.

Adaptation - Essentials

Posts: 42

(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,882

Re: Compound parabolic reflectors - earth based zmp solar concentrator

I was looking at a small satelite reciever dish mounted on the roof of my home to produce heat with. I have seen used ones as well as those being tossed into the garbage dumps so it should not be to hard to get one to play with. Was looking to coil copper tubing and attach a flat plate to the coil so as to hold it together with a backer plate. These would be black so as to absorb the most energy into the fluid which I am still looking as its going to get cold up here during this time of year which can be compensated for by what is called a drain back system. In either case that working heated fluid would then go to a storage tank so as to absorb as much heat as I can during the day hours. That fluid would be pumped up to the roof top colleting units and then from the tank out to small room heat units simular to a cars heater core with a fan.