Talk on SunCube in Pune this evening

[Manu Sharma]

Members based in and around Pune might want to attend this talk by Mr. Deepak Kelkar of Square Engineering, Indian licensee of SunCube, a pioneering Concentrated Photovoltaic product. 

The talk is being organised by Indian Institute of Production Engineers (IIPE), Pune

What : Renewable Energy sources – Specially Solar.
Speaker : Mr. Deepak Kelkar
Venue: COEP Pune Production Engineering department.
Date: Wednesday, 18th Noember 2009.
Time: 18=30 hrs. to 20=00 hrs.
Charges: Free for all. No registration required.

Mr. Deepak Kelkar is mechanical engineer. He has huge experience in sugar industry to install and commission different equipments. He has started Squre Engineering Pvt. Ltd. in 1986, as EPC company and they are specialized in Renewable Solar energy. They have collaboration with many renouned names in the field. They are working in renewable energy sources since 1992. Mr. will be sharing his experieces in this field. Suare Engineering has developed SUNCUBE – innovative system. The system genrates DC power by using “Tripple Junction PV cells under concentration of 1000X of Sun light.

Source: http://punetech.com/renewable-energy-sources-solar-energy-iipe-meet-18th-nov

Thanks,

Manu

[Manu Sharma]

If anyone in Pune got to attend this, please share your notes!

Thanks,

Manu

[Ranjit Deshmukh]

Hello everyone,

I happened to attend Square Engineering's presentation in Pune.

Mr. Kelkar, the CEO of Square gave the presentation. There was no
product demonstration (expectedly).

The Suncube is a 300Wp CPV unit. It has nine units in one module, each
with a 1 cm2 triple junction PV cell. The concentration is 1000x. The
fresnel lens used is ~33cmX33cm. Efficiency is approximately 37%.
What I thought interesting was that the tracking mechanism is a very
small parasitic load. Tracking is done by sensing the voltage of the
actual triple junction cell, basically homing down on the position
that gives the highest voltage. It also memorizes the positions along
with the time of day, so it can reference that for the next day, in
case there are intermittent clouds. It rests face down during the
night. The next morning it computes the starting point based on the
setting position on the previous day.

Cost is Rs 45,000 per unit, which roughly results in USD 3.3/Wp, which
is quite low given that PV is between USD 2-4/Wp today. And of course,
the cost of generation is more important, and CPV being more efficient
than normal PV will generate more. According to Square, the cost of
generation is between Rs 3-4.5/kWh for a 25 year plant. That is really
low, and is at grid parity. I am sure of all the assumptions in their
calculations, but even if it is double that, it is still way
attractive compared to normal PV. This cost of generation most likely
does not include the IRR etc for the developer. So it might be Rs 6-7/
kWh, still more attractive to the Rs12-15/kWh for normal PV.

Here are the specs of Suncube: http://www.squareengg.com/Images/SUNCUBE%20SPECIFICATIONS.pdf

Square also talked about their "Big Dish", a concentrating parabolic
dish.

Cheers,
Ranjit

On Nov 19, 11:52 am, Manu Sharma <orangeh...@gmail.com> wrote:
> If anyone in Pune got to attend this, please share your notes!
>
> Thanks,
> Manu
>

> On Wed, Nov 18, 2009 at 11:27 AM, Manu Sharma <orangeh...@gmail.com> wrote:
> > Members based in and around Pune might want to attend this talk by Mr.
> > Deepak Kelkar of Square Engineering, Indian licensee of SunCube, a
> > pioneering Concentrated Photovoltaic product.
>
> > The talk is being organised by Indian Institute of Production Engineers
> > (IIPE), Pune
>
> > What : Renewable Energy sources – Specially Solar.
> > Speaker : Mr. Deepak Kelkar
> > Venue: COEP Pune Production Engineering department.
> > Date: Wednesday, 18th Noember 2009.
> > Time: 18=30 hrs. to 20=00 hrs.
> > Charges: Free for all. No registration required.
>
> > Mr. Deepak Kelkar is mechanical engineer. He has huge experience in sugar
> > industry to install and commission different equipments. He has started
> > Squre Engineering Pvt. Ltd. in 1986, as EPC company and they are specialized
> > in Renewable Solar energy. They have collaboration with many renouned names
> > in the field. They are working in renewable energy sources since 1992. Mr.
> > will be sharing his experieces in this field. Suare Engineering has
> > developed SUNCUBE – innovative system. The system genrates DC power by using
> > “Tripple Junction PV cells under concentration of 1000X of Sun light.
>
> > Source:

> >http://punetech.com/renewable-energy-sources-solar-energy-iipe-meet-1...
>
> > Thanks,
> > Manu

[Manu Sharma]

Hi Ranjit,

Good to know you could attend the talk and thank you for sharing the notes.  

A couple of clarifications - the figure you mentioned, Rs.45,000 - is that the cost to manufacturer (Square), the cost to distributor or the retail price?  

If that's the retail price than that's really attractive and even if there's a 30% markup on top of this, it's still very good. I ask this because the figure I heard sometime back (for retail price) was higher.

Second, did Mr. Kelkar mention the annual number of kWh one unit would generate at a location in India?

Thanks,

Manu

On Fri, Nov 20, 2009 at 1:06 PM, Ranjit Deshmukh <ranji...@gmail.com> wrote

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[Thaddeus Ward]

Hello all,

One thing to keep in mind is CPV sensitivity to diffuse radiation.
CPV requires direct radiation to work effectively. In areas with high
humidity but lots of sunlight the overall efficiency of any CPV can be
greatly reduced. It will capture 30+% of the direct rays but there
are many fewer direct rays to work with.

Just an important factor to keep in mind when considering the overall
economics of any particular project.

-TW

On Nov 20, 5:28 am, Manu Sharma <orangeh...@gmail.com> wrote:
> Hi Ranjit,
>
> Good to know you could attend the talk and thank you for sharing the
> notes.
>
> A couple of clarifications - the figure you mentioned, Rs.45,000 - is that
> the cost to manufacturer (Square), the cost to distributor or the retail
> price?
>
> If that's the retail price than that's really attractive and even if there's
> a 30% markup on top of this, it's still very good. I ask this because the
> figure I heard sometime back (for retail price) was higher.
>
> Second, did Mr. Kelkar mention the annual number of kWh one unit would
> generate at a location in India?
>
> Thanks,
> Manu
>

> On Fri, Nov 20, 2009 at 1:06 PM, Ranjit Deshmukh <ranjits...@gmail.com>wrote

[moresh kokane]

Hi

 

Does any one know where suncube sources its 1 cm2 triple junction PV cell. Have they developed on their own or is it sourced from EMCORE ? Does any one know what is the cost breakup in terms of cost of the PV cell, actual concentrator and orientation mechanism. I am more interested in the cost of the PV cells.

 

Thanks

Moresh

[Manu Sharma]

On Fri, Nov 20, 2009 at 9:13 PM, Thaddeus Ward <thadde...@gmail.com> wrote:

Hello all,

One thing to keep in mind is CPV sensitivity to diffuse radiation.
CPV requires direct radiation to work effectively.  

Hi Thaddeus,

That's a valid point. Apart from humidity, particulate matter in the air, smog and the Asian brown cloud is also known to affect DNI. The jury is still out though how significantly will any of this affect SunCube output. 

What's very interesting about this issue is that GGE has just introduced a warranty for the SunCube. If your output is less than the minimum range specified by GGE (based on the NASA satellite data), and conditional to the natural degradation of PV output, the company will either pay you for the shortage or provide additional SunCubes at own cost. 

I believe no other company offers such a warranty -- most manufacturers would not even commit the annual output of their flat panels.  

In this discussion it should also be noted that CPV is ideal for desert locations. Fortunately, there are several large areas in the Western region of India away from human habitation that receive scanty rainfall and are unaffected by the pollution problem. So conceivably, multi-megawatt scale centralised installations in such areas should work quite well.      

Thanks,

Manu

[Manu Sharma]

On Fri, Nov 20, 2009 at 10:18 PM, moresh kokane <mor...@gmail.com> wrote:

 

Does any one know where suncube sources its 1 cm2 triple junction PV cell. Have they developed on their own or is it sourced from EMCORE ?

Moresh, 

Developing multi-junction cells requires an investment in infrastructure in the range of hundreds of millions of dollars if I'm not wrong. Although a few new players have recently been trying to enter this business, there are only two companies that manufacture III-V cells currently - Spectrolab and Emcore. 

Both of them developed the technology in collaboration with NREL researchers Jerry Olson and Sarah Kurtz who invented and pioneered this technology over the last three decades.

SunCube sources its cells from Emcore.  

 

Does any one know what is the cost breakup in terms of cost of the PV cell, actual concentrator and orientation mechanism. I am more interested in the cost of the PV cells. 

The cells are about $10 a piece if you place a large enough order.   

 

Thanks,

Manu

[moresh kokane]

Thanks Manu, this is very good information.

 

From the technical specs listed on EMCORE site

 

http://emcore.com/assets/photovoltaics/CTJ_B_Web.pdf

 

The peak efficiency of 39 % occurs at around 500 X solar concentration and it then falls down to around 36 % at 1000 X.

 

From what I understand the concentrator area to solar cell area ratio represents the savings achieveable as the solar cell is the most expensive of all the pieces. But a drop of efficiency is also noted with greater concentration. Suncube aims for 1000 X concentration with each of its 9 Fresnel lenses. So we have to variables effective cost and efficiency that have to be paired off against each other.

 

I am trying to determine answers to couple of questions, is the drop in efficiency due to the rise in temperature or a physical limit imposed by the solar cell. The second question is pretty much derived from the first. Is 1000 X the highest ratio at which a reasonably high efficiency (36%) can be maintained. EMCORE data says that 1000 X is the level of concentration which has been 100 % tested. What happens if we go higher, does the performace drop drastically ?

 

Thoughts ?

 

Regards

Moresh

--

[Manu Sharma]

On Sat, Nov 21, 2009 at 1:33 AM, moresh kokane <mor...@gmail.com> wrote:

 

I am trying to determine answers to couple of questions, is the drop in efficiency due to the rise in temperature or a physical limit imposed by the solar cell. The second question is pretty much derived from the first. Is 1000 X the highest ratio at which a reasonably high efficiency (36%) can be maintained. EMCORE data says that 1000 X is the level of concentration which has been 100 % tested. What happens if we go higher, does the performace drop drastically ?

Moresh, 

You'll have to speak with the technical team at Emcore to get those answers. But I don't think efficiency is the only thing important in CPV. You're looking at it in terms of flat panels. In a CPV device when you have raised the concentration so high, efficiency of the cells stops being a matter after some time. 

It's simple math. Here's why: a CPV device with 1000 sun concentration at 35% efficiency will still generate much more energy than a 800 sun device with 40% efficiency or 500 sun device with 45% efficiency (which I should add, no one has yet achieved). 

Let's say, all the above devices have a PV material rated at 1W in normal sun condition. Let's see how much energy would these generate.

500X -- 45% efficiency

Power rating* = 500W

Energy output / hr*  = 225 Wh

800X -- 40% efficiency

Power rating* = 800W

Energy output / hr*  = 320 Wh

1000X --- 35% efficiency

Power rating* = 1000W

Energy output / hr* = 350 Wh

* under peak sun conditions

Clearly, higher concentration is a winner. Even though the efficiency is low, the output is significantly greater. 

This, of course, is a slightly exaggerated example, in real life, the difference in efficiency from low concentration to high is not that great. The Emcore spec sheet shows efficiency from 500x to 1182x dropping from 39% to 36.3%.

When it comes to concentration, if you look at competition and where they stand -- they are nowhere close to SunCube. Concentrix, which was mentioned here previously and solfocus -- both of these technologies work at only 500 X concentration. 

The latest iterations of SunCube are well over 1000 suns which would easily generate more than DOUBLE the output using the same amount of PV material.

The obvious question then is, why don't everyone works at high concentrations? I think that's because it's very hard to get it right. Which is why I respect and admire Greg's invention so highly

Thanks,  

Manu

[Greg Watson]

Hi Moresh,

 

If you note the IV curves on that old data sheet, you will see they test the cells to 1,500 suns or 1,500 W/cm2. With the latest cells the peak efficiency is well over 1,000 suns. We have been told that Emcore has tested their cells at 3,500 suns and saw no deterioration. The drop in efficiency as the concentration increase is caused by internal IR losses from the increased current generation which is a very linear function of the W/cm2. Again look at the series of IV curves at different W/cm2 of applied energy.

 

Hint on designing a CPV system. You do not design the optical system to work at the peak efficiency as seen in the lab but at the average peak delivered by the real world sun.

 

For the SunCube and the current Emcore CPV receivers we are working with, 1,370 Suns geometric concentration ratio achieves the peak biasing under real world sun conditions. Our Eko MP-160 IV curve tracer has shown STC module efficiencies of 35% and on sun efficiencies of 31%. Others have claimed 29% for their CPV products.

 

http://www.greenandgoldenergy.com.au/Documents/SunCubeIVCurve20081004.pdf

 

Even though the Eko indicated 334 Wmp on that SunCube, GGE decided to be conservative and rate the SunCube generally at 300 Wdc STC minimum.

 

Here are the SunCube spec sheets, output warranty and kWh generation warranty:

 

http://www.greenandgoldenergy.com.au/Documents/GGESunCubeSpecSheet20090903a.pdf

 

http://www.greenandgoldenergy.com.au/Documents/GGESunCubekWhGenerationWarranty20091118b.pdf

 

I trust this information is of value and helpful in your understanding of the SunCube technology?

All the best,
Green and Gold Energy Pty., Ltd
Greg Watson, CEO
7 Provident Avenue, Glynde, 5070
South Australia, Australia, +61 8 8365 5844
http://www.greenandgoldenergy.com.au
 
"SunCube" and "SunBall Solar Battery" are
trademarks of Green and Gold Energy Pty Ltd
 

[Greg Watson]

Hi Moresh,

 

The CPV receiver module is sourced from Emcore. It was jointly developed by Emcore and GGE for the SunCube's optical system and energy levels. The development process took around 12 months to achieve both Emcore's and GGE's goals. The production process is almost totally automated with automatic testing at every stage of cell and module production, including final testing of each completed module.

 

It is a very good module. We have seen cell efficiencies over 42%. Our last 50k modules tested out at 40% average efficiency with 1,000 W/cm2 (1.000 suns) applied to the cell's 1x1cm area.

All the best,
Green and Gold Energy Pty., Ltd
Greg Watson, CEO
7 Provident Avenue, Glynde, 5070
South Australia, Australia, +61 8 8365 5844
http://www.greenandgoldenergy.com.au
 
"SunCube" and "SunBall Solar Battery" are
trademarks of Green and Gold Energy Pty Ltd
 

----- Original Message -----

From: moresh kokane

To: green...@googlegroups.com

Sent: Saturday, November 21, 2009 3:18 AM

Subject: Re: [Green-India] Re: Talk on SunCube in Pune this evening

[Greg Watson]

Hi Thaddeus,

Some points to consider:

1) Direct bean is around 85% of global energy that a flat panel collects.

2) As direct beam drops so to does global.

3) The best global is around 200 W/m2 and at that solar energy level silicon
based flat PV flat panels suffer significant conversion efficiency loss
while CPV has a very flat conversion efficiency over a range exceeding
1000:1.

4) Generally the kWh/m2/day that is available to a 2 axis tracked
concentrator and to a fixed latitude tilt flat panel are about the same.

5) CPV has around 25% of the loss from elevated ambient temperatures as does
flat panels.

6) CPV outperforms PV under cloudy skies as show in these two examples
comparing Glasgow Scotland and Adelaide Australia.

Glasgow:
http://www.greenandgoldenergy.com.au/images/SunCubeVersusFlatPanelGlasgow.JPG

Adelaide:
http://www.greenandgoldenergy.com.au/images/SunCubeVersusFlatPanelAdelaide.jpg

Thaddeus, there are a lot of incorrect urban myths surrounding CPV and PV
and clouds.

All the best,
Green and Gold Energy Pty., Ltd
Greg Watson, CEO
7 Provident Avenue, Glynde, 5070
South Australia, Australia, +61 8 8365 5844
http://www.greenandgoldenergy.com.au

"SunCube" and "SunBall Solar Battery" are
trademarks of Green and Gold Energy Pty Ltd

----- Original Message -----
From: "Thaddeus Ward" <thadde...@gmail.com>
To: "India's Energy Future and Sustainable Living"
<green...@googlegroups.com>

> > > > What : Renewable Energy sources � Specially Solar.

> > > > Speaker : Mr. Deepak Kelkar
> > > > Venue: COEP Pune Production Engineering department.
> > > > Date: Wednesday, 18th Noember 2009.
> > > > Time: 18=30 hrs. to 20=00 hrs.
> > > > Charges: Free for all. No registration required.
>
> > > > Mr. Deepak Kelkar is mechanical engineer. He has huge experience in
> > sugar
> > > > industry to install and commission different equipments. He has
> > > > started
> > > > Squre Engineering Pvt. Ltd. in 1986, as EPC company and they are
> > specialized
> > > > in Renewable Solar energy. They have collaboration with many
> > > > renouned
> > names
> > > > in the field. They are working in renewable energy sources since
> > > > 1992.
> > Mr.
> > > > will be sharing his experieces in this field. Suare Engineering has

> > > > developed SUNCUBE � innovative system. The system genrates DC power
> > > > by
> > using
> > > > �Tripple Junction PV cells under concentration of 1000X of Sun

[Greg Watson]

Correction:

3) The best diffuse is around 200 W/m2

[moresh kokane]

Thank you Greg and Manu

I am going to study this in detail before I get back but I am very excited by this product offering and the technology in general. I am based in Boston and have been trying to determine the viability of Solar Stirling for the last couple of years. Now it seems like CPV has stolen a clear march on Stirling systems.

All the best !

Moresh

> > > > What : Renewable Energy sources – Specially Solar.

> > > > Speaker : Mr. Deepak Kelkar
> > > > Venue: COEP Pune Production Engineering department.
> > > > Date: Wednesday, 18th Noember 2009.
> > > > Time: 18=30 hrs. to 20=00 hrs.
> > > > Charges: Free for all. No registration required.
>
> > > > Mr. Deepak Kelkar is mechanical engineer. He has huge experience in
> > sugar
> > > > industry to install and commission different equipments. He has
> > > > started
> > > > Squre Engineering Pvt. Ltd. in 1986, as EPC company and they are
> > specialized
> > > > in Renewable Solar energy. They have collaboration with many
> > > > renouned
> > names
> > > > in the field. They are working in renewable energy sources since
> > > > 1992.
> > Mr.
> > > > will be sharing his experieces in this field. Suare Engineering has

> > > > developed SUNCUBE – innovative system. The system genrates DC power
> > > > by
> > using
> > > > “Tripple Junction PV cells under concentration of 1000X of Sun

[Manu Sharma]

On Sun, Nov 22, 2009 at 8:47 PM, moresh kokane <mor...@gmail.com> wrote:

Thank you Greg and Manu

I am going to study this in detail before I get back but I am very excited by this product offering and the technology in general. I am based in Boston and have been trying to determine the viability of Solar Stirling for the last couple of years. Now it seems like CPV has stolen a clear march on Stirling systems.

CPV is indeed a very exciting space to be in right now as it's one of the very few large scale cost-competitive renewable technologies out there that is ready to be deployed today. Good luck. 

 

Manu

[M V Bhaskar]

Hi Manu

If the Triple Junction cells are $10 per cm2 and 9 are used in one
Suncube.
Therefore the cost of 9 cells in a 1 sq meter Sunbube is just Rs 4500.
The complete cost of a suncube is stated at Rs 45000.
The cells are supposed to be the most expensive part of the system,
how is it that they are just 10% of the total cost?

The positive side of this is that there is good scope for reducing the
system cost in future with higher volumes and mass production.

best regards

Bhaskar

On Nov 20, 10:07 pm, Manu Sharma <orangeh...@gmail.com> wrote:

[moresh kokane]

Do not forget the collector material which is the lenses. Fresnel lenses of 1 ft dia. cost around 10 - 15 $ for retail. Multiply that by 9 and add to the cost.

Then comes the sealed aluminum box. Diodes, microcontroller tracking mechanism. 2 motors for 2 degrees of Freedom, research and Development costs, debt interest (if any). Labour costs, assembly line, manufacturing costs, licensing, plus Square Engg. has to make some profits as well.

Although there might be potential for reduction in case of mass production and with subsidies and as the product gains more sales. 

Also as Greg pointed out the cells could potentially work with 3500 X concentrations which could lead to further savings (lens are cheaper than cells of the same area). But a 3500 X lens will be larger (around 18.5 cm X 18.5 cm), smaller lenses are available more readily and as you go higher in size, manufacturing complexity and cost rises.

I am eager to learn about what was referenced as "Big Dish". Another interesting implementation (again from Oz) I came across

http://www.solarsystems.com.au/documents/SolarSystems_CS500MkVDish_US_Web.pdf

This is a large dish, the site has 2 figures for optical concentration 500 and 1000 in 2 different places. Collector cost is 80 % and panels cost 20 % of total. This allows them to potentially replace the panels as technology improves with out throwing out everything and beginning anew.

There are other implementations of CPV as well which combine more units as opposed to Suncubes 9. Advantage being same motor and support tracking infrastructure for more units, power thus saving costs. But larger dishes are also more difficult to manufacture, as you go higher than 12 ft in dia. the support structure has to be more rigid and price actually rises exponentially.

Now I may miss something here, does any one know what are the advantages offered as we go for bigger concentrators considering the fact that 1000 X (or 3500X) is the highest concentration we can go without deteriorating performance.

Moresh

[Manu Sharma]

On Mon, Nov 23, 2009 at 7:10 AM, M V Bhaskar <bhaska...@gmail.com> wrote:

 

The cells are supposed to be the most expensive part of the system,
how is it that they are just 10% of the total cost?

Hi Bhaskar,

The cells are not the most expensive part of the system. 

On another note, GGE even has a provision of allowing consumers to upgrade the cells when higher efficiency ones come out, though I do think that it will be allowed only after energy payback from the original cells has been achieved.

Thanks,

Manu 

[Manu Sharma]

On Mon, Nov 23, 2009 at 9:20 AM, moresh kokane <mor...@gmail.com> wrote:

I am eager to learn about what was referenced as "Big Dish".

Moresh, 

Square has a collaboration with another Australian company, Wizard Power Pty Ltd, that is into dish based solar thermal systems and has a unique ammonia based thermo-chemical energy storage component. You'll find more info on it in the presentation of Square Engineering at solar thermal workshop organised by IIT Bombay's Energy Systems Engineering department last year.

Thanks,

Manu

 

[Dr. Srinivasa Chakrawarthy Ravuri]

Moresh,

                Is cooling not an issue at 3500x ?

--Chakrawarthy

--
Dr. Srinivasa Chakrawarthy Ravuri
Renewable Energy Technopreuner

Solar-thermal; Bio-gas; Rain-water harvesting
chakra...@gmail.com; 09908212812

[Sandeep Shriya]

This discussion has gone on for a long time now.

 

Would it be possible for someone to help the rest by summarising various issues, pros/cons etc? This is a mere request. Nothing more to it.

 

Thanks in advance,

Sandeep Shriya

Mobile: (+91) 9833005253

 

P Please don't print this e-mail unless you really need to.

 

From: Dr. Srinivasa Chakrawarthy Ravuri [mailto:chakra...@gmail.com]
Sent: 23 November 2009 12:04
To: green...@googlegroups.com
Subject: Re: [Green-India] Re: Talk on SunCube in Pune this evening

 

Moresh,

[moresh kokane]

Yes, but it is an issue even at 1000 X. I am not aware of any CPV implementation using 3500 X, right now all we know is EMCORE has tested at 3500 X and it seems to work without significant deterioriation. A 3500 X system would require an improved cooling system than a 1000 X system

 

I do remember coming across a CPV system that floats the lenses over a water body (which also acts as a heat dissipator) , although cant seem to find it now.

 

Moresh

[Manu Sharma]

On Mon, Nov 23, 2009 at 8:54 PM, moresh kokane <mor...@gmail.com> wrote:

 

I do remember coming across a CPV system that floats the lenses over a water body (which also acts as a heat dissipator) , although cant seem to find it now.

Pehaps, Sunergy? The is the original liquid solar array company owned by university professors who pioneered the concept. 

Others like Pyron solar have picked it up from them.  Both are Australian companies.

Manu

[moresh kokane]

It was Pyron Solar, although Sunenergy has an interesting design as well. Thanks again Manu.

SunCube uses a passive cooling mechanism, does any one know the temperature at the hot spot ? What is the temperature required for optimum operation of the solar cell. The difference would be the heat dissipation required.

In case of a water floating system heat dissipation wont be a major issue. The water is evaporation resistant (I am thinking a thin film of oil might be covering it). 

But in case of a system like Suncubes which uses passive cooling using the aluminum box, the surface area of the aluminum exposed becomes important. This is a 3 mm thick aluminum box, does any one know how much surface area would be required for achieving the required cooling.

I am basically trying to get some technical data on the cooling implementation.

Regards

Moresh

[moresh kokane]

The specs do mention Temperature of hottest point of aluminum skin at STC: ~65 deg C, but is this the  temperature at the hot spot or is this the ambient temp of the box as the heat dissipates ? For 1000 X concentration is that the max. temp reached at the hotspot ?

I think I am missing something.

Moresh 

[Manu Sharma]

On Tue, Nov 24, 2009 at 6:32 AM, moresh kokane <mor...@gmail.com> wrote:

The specs do mention Temperature of hottest point of aluminum skin at STC: ~65 deg C [...] For 1000 X concentration is that the max. temp reached at the hotspot ?

65 deg is the temp after heat is dissipated through the aluminium sheet. You can easily calculate waste heat since you know the efficiency. So if 1000 W (peak) is falling on one sq. m and 350 W (35%) is being converted into electricity. You have 650 W left as waste heat. 

 

In case of a water floating system heat dissipation wont be a major issue. The water is evaporation resistant (I am thinking a thin film of oil might be covering it). 

The problem here is, how do you get rid of the heat once collected? You'd need to keep tanks full of cold water for any large installation. It's possible to run it through an earth tunnel or something but then it puts unnecessary limits on a system. Passive cooling is a superior solution. 

Manu

[soumyabrata rahut]

does any one know what is the drop in efficiency / output per deg rise in temperature for the suncube ?
warm regards
somo

2009/11/24 Manu Sharma <orang...@gmail.com>

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Soumyabrata Rahut
Consultant
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(Prayas Energy Group)

[Manu Sharma]

On Tue, Nov 24, 2009 at 11:48 AM, soumyabrata rahut <soumyabr...@gmail.com> wrote:

does any one know what is the drop in efficiency / output per deg rise in temperature for the suncube ?

It's significantly less than flat panels.

Thanks,

Manu

[soumyabrata rahut]

i'd require a number if possible. i would like to do some ROI calculations.

warm regards
somo

2009/11/24 Manu Sharma <orang...@gmail.com>

On Tue, Nov 24, 2009 at 11:48 AM, soumyabrata rahut <soumyabr...@gmail.com> wrote:

Manu

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[deepak kelkar]

0.06% drop in efficiency per deg rise above ambient treated as 25 deg.  This data is available on www.emcore.com in data sheet for use of triple junction cell under concentration.  The PV silicon drops at 1.14%.  Here in case of Suncube voltage drops however current increases which is beneficial to charge batteries as MPPT device operates on IV curve at 21-22V dc.  You will find that Voc of the suncube is 27V and very small drop in voltage as compared with PV silicon.  I need to mention that PV silicon Voc is 21V in case of 75/100 watt modules and IV curve has long bend as against sharp knee bend of IV curve of Suncube.

Regards

Deepak

On Tue, Nov 24, 2009 at 11:48 AM, soumyabrata rahut <soumyabr...@gmail.com> wrote:

--
Deepak Kelkar
Director
Square Engineering Pvt Ltd.
Pune
Cell: 9422310250

[Manu Sharma]

On Tue, Nov 24, 2009 at 12:16 PM, deepak kelkar <squar...@gmail.com> wrote:

0.06% drop in efficiency per deg rise above ambient treated as 25 deg.  This data is available on www.emcore.com in data sheet for use of triple junction cell under concentration.  The PV silicon drops at 1.14%.  

Thanks Mr. Kelkar.

 

In other words, at ambient temp of 40 deg and 45 deg (not uncommon in India): 

Flat panels will have their efficiency drop by 17% and 23% respectively
Triple Junction cells will see their efficiency drop of a mere 0.9% and 1.2% respectively

Even if one considers 65 deg ambient for III-V cells, the efficiency will not drop by more than 2-3%. This is a huge difference. 

Thanks,

Manu

[Dr. Srinivasa Chakrawarthy Ravuri]

Mr. Kelkar,

                    Congratultaions for this product.

BTW: What is the temp. inside the box ?

--Chakrawarthy

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[Dan Kegel]

On Mon, Nov 23, 2009 at 10:46 PM, deepak kelkar <squar...@gmail.com> wrote:
> [suncube has] 0.06% drop in efficiency per deg rise above ambient treated as 25 deg.
> ... PV silicon drops at 1.14%.

I'm no expert, but it seems that others have different figures for PV silicon
efficiency as a function of temperature.

For crystalline silicon,
http://en.wikipedia.org/wiki/Solar_cell claims PV drops at 0.50%/°C
http://www.hindawi.com/journals/ijp/2009/732093.html gives more detail,
and several references.

For polycrystalline silicon:
http://www.vjol.info/index.php/ASEAN/article/viewPDFInterstitial/411/334
has some measurements (in Brunei's conditions) and also several references.

Not sure what to make of the differences between the quoted figures,
maybe it depends on the exact kind of cell?
- Dan

[Greg Watson]

-0.5% per deg C is around the accepted temp related conversion derivation for silicon flat panels plus their conversion loss at diffuse leq 200 w/m2.
Best regards,
Greg Watson, CEO,
Green and Gold Energy Pty. Ltd.,
7 Provident Avenue, Glynde, 5070,
South Australia, Australia,

Sent from my BlackBerry Storm

-----Original Message-----
From: Dan Kegel <da...@kegel.com>
Date: Tue, 24 Nov 2009 05:12:48
To: <green...@googlegroups.com>
Subject: Re: [Green-India] Re: Talk on SunCube in Pune this evening

[moresh kokane]

Water has a high specefic heat, also since the volume is high, the difference in temperature of water and at hot spot will be high enough. I dont think that a continuos circulation of water will be required and the same water can be enough through the day. In the night it will cool off.

 

I do agree however that a passive cooling system like the one employed by Suncube makes more sense as requirement of water in hot areas adds an extra barrier (whether or not continuos circulation is required).

 

Now assuming we have to dissipate 650 W, does any one know how much surface area of aluminum would be required for the heat dissipation. Any thermodynamics experts in the group here to help with ideas ?

 

I think there can be a design improvement to suncube solution, and I am trying to determine numbers for the same.

 

Also my interest in this is not just commercial. Everytime I visit India it pains me to see that we still suffer the ignominy of "load shedding". We pride ourselves to be a free Democracy, it is our responsibilty to ensure that all of our citizens have access to opportunity. Our economic growth will sputter without energy, and we are not an oil surplus country.

 

We have to make Solar work.

 

Moresh

[Keef Wivaneff]

http://www.todaytonightadelaide.com.au/stories/sun-cube-saga

http://www.todaytonightadelaide.com.au/stories/sun-cube-part-2

Oh dear!