Author Topic: Making decent solar panels part 1  (Read 28304 times)

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oztules

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Making decent solar panels part 1
« on: February 10, 2011, 02:28:36 AM »
It's something I said I would never do..... but now I have.



If you have no value on your time, and want to do your own DIY solar cells, then it has always been possible to cobble some cells together, stick them to a surface, and place plastic or glass over them, measure the output..... and generally feel good.

A fancy frame helps with the karma... but you know in the end it is only temporary.

As the water vapour creeps into the sealed wooden framed ones, or the window glass you scrounged up...breaks because of the heat/cold and localized heating in particular cells, and it all falls in a heap. It can get pretty sad for a lot of devotees that have tried.

There are plenty of youtube stories and how too's...... but all (but the ones using sylgard (or whatever it's called)) are doomed to failure)...... except those who have tried to use EVA (ethylene vinyl actetate).

I viewed a few treatments on the youtube sites, and none of them inspired a great deal of comfort. They all revolved around using a heat gun and a heap of good luck to melt the EVA around the cells, and onto the glass.........

Why I thought, did they make solar cells 30 years or more ago, and still basically the same today...and yet the amature panel maker comes up with lots of bad ways to do it??

I pondered this for a while, and in the meantime, a plumber friend turned up with a few solar hot water panels..... also  25 or more years old..... they were stuffed..... but they did use tempered glass, and it was iron free glass.... and it was free glass ( this was the clincher).

So I sat and looked at a few 2 sq meter panels (1x2m).......... yep, had to have a go too.... but it cant be cut!



This is where I decided to look around the world at the current state of play. This was sobering, no real effort at making proper panels like the big boys  built without the big boys price tags... why not?

It appears that folks thought you needed a laminator style of machine, which were very expensive, and a barrier to making your own. But if you look at what needs to be achieved, it is really only a few simple steps.... so lets look at the how and why.


Traditionally they use a sheet of glass (iron free tempered if you can get it), a sheet of EVA, the cells themselves, another sheet of EVA, and whatever your having yourself. After the last EVA sheet, you only really need to put something there that will not wick, and will give you something for the very very sticky EVA to bond to that is not your "jig" It can be painted later if you want more protection. Usually they use tedlar, but really any inert material will do for protection.

The simple theory of what we are trying to achieve is this:
We need to get the cells fully encapsulated in a UV stable envelope, that resists water and air from denaturing the cells. It must allow for differential expansion rates to occur between the silicon wafers, the glass and the medium itself....... and no bubbles.

Ethelyene vinyl acetate is a plastic sheet .5mm thick. It is soft plastic in texture and seems innocuous enough....... however, when it gets to only 65 degres C, it melts. This means that we need not get to very high temperatures to get something to happen.

I'll bet there are plenty of hopefuls ( like me for instance) that grabbed some EVA, some glass, and the wifes oven, and made a prototype cell......but it is filled with bubbles!..... It does stick to the glass and, it envelops the cells well, but it is useless because of the bubble population.

It is at this point  that you start to get a bit anxious about where to get a laminator...... but you don't need one. We just need to emulate what it does.

Next thing we look at is what happens when it melts. To get the EVA to be useful, we need to get enough energy into the stuff to cross link the molecules.  It changes the way the material behaves, and increases the melt point considerably as well. At low temp (65C-80C) it melts to itself very well, but is only slowly converted into the final product, so we have to keep it at these temperatures for long periods..... but as we increase temp, things happen a whole lot faster, and 5 mins may be enough at 145c to get it to cross link, and stick very strongly to the glass and the cell itself.

It also needs some encouragement from pressure..... or a vacuum perhaps, and use the air pressure to do the job of supplying the pressing force.

Now we know it  works perfectly well without vacuum, but you will have myriads of fine bubbles.... blocking out the sunlight.... not so perfect after all.

So we need a vacuum pump. Ideally one that can draw a near perfect vacuum. The vacuum you can achieve sort of directly relates to the bubbles you will get left with. High vacuum.... no bubbles. It's that simple. The vacuum will also press the cells very firmly (200 plus pounds per cell) against the glass, and this will help the glass bond, and make for a very flat cell, with no voids in the plastic envelope.............as always there is a but:... you must have NO leaks at all, or you will get uneven vacuum in the sheets, and you will get bubbles forming.... probably in the inter cell space, but bubbles all the same.

The heating profile I will use is like this:

15 mins at room temperature with full vacuum
15 mins at 65C with full vacuum
70-80 mins at 100C (or thereabouts with full vacuum

And if we can get the temp to rise some more.... then good. Even if the plastic garbage bag fails at this point, it's work is done for all practical purposes... better if it does not..but we get what we can.

So it looks doable.

First step for me was a BIG oven.

An oven that would handle the 2 meter by one meter panes of glass that came from out of the solar water panels. (it turns out that for some quirk of history, there are plenty of these old solahart type panels laying around over here).


We know that the temperatures involved are not high in order to achieve the bonding and cross linking that is required to get the cells to be protected, and pressed against the glass without any bubbles..... so I started with a wooden construction..... yes for an oven.

I had recently pulled down a wool shed for a fellow, and I was given the wood.... lots of old 4x2 hardwood.... so this was to be the frame
It looks like this:



I was also given some packing material in 8x4 foot sheets of low grade 3/4" pineboard.(someones kitchen apparently turned up in them). These would serve for the bottom and lid of the oven. For the sides I just used some of the old floor boards from the shearing stand.....

The whole thing is lined with ceiling roof bats insulation and then all held in the walls with a sheet of TYVEC building wrap material.... could be anything really.... even paper.



Ok, that gets us the oven walls and floor, and the lid was just a sheet of the 8x4 pineboard with insulation laying on the top.... Now we have an insulated container that will take our panel.





What this means to the 60watt panel builder.....is that even an insulated cardboard box will do for an oven (I used one with a fan heater blowing from in front for the initial trial, with blankets and dooners for the insulation...... perfectly good for a 60 watt panel)


Next step is a heating element.

This was simply solved by destroying a fan heater/radiator. These things draw about 2000 watts and incorporate a fan and a nichrome heating coil. They spill out a fair stream of not too hot air, so are unlikely to melt our plastic bags (comes later) when we bring the oven up to temperature.

I built the heater body out of a "think safety" sign (ironic really), which housed the heating element at one end, and the fan motor at the other. The fan blades were plastic, and would melt in this environment (proximity to the glowing element), so I stole the aluminium blades from my big MIG welder, and put the plastic ones back in that.

This gives us a 2000w heater that blows hot air..... but not too hot,and will allow us to gently heat the oven up to about 100-120 degrees, without any cunning trickery required to temp control it. Because the oven is so well insulated...... we just keep adding watts from the heater until we get to where we want.

Finished it looks like this:



Perhaps finished was too strong a word to use...... but it does work.



Thats about as much as we can do with this software in one hit, so ...

Thats Part one finished


............oztules
« Last Edit: December 05, 2016, 07:16:15 PM by JW »
Flinders Island Australia

gsw999

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Re: Making decent solar panels
« Reply #1 on: February 10, 2011, 04:07:25 AM »
Hopefully by summer I will get some solar panels knocked up but I will be using old large double glazing panels, looking forward to seeing the finished article.

walp

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Re: Making decent solar panels
« Reply #2 on: February 10, 2011, 04:22:30 AM »
Amazing! :)
But it seems very advanced!

I have a couple of cells that need to be put togheter in a box.
If I use perspex\PMMA\Plexiglass at least the cover will not break, and if I make a sealed wooden box with built in ventilating fan, wouldnt that be enough?  
Unlike you Aussies, I live in Sweden, and we dont have super high temperatures or super humid air,  ::)



Keep us posted with the process!

Volvo farmer

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Re: Making decent solar panels
« Reply #3 on: February 10, 2011, 05:09:45 AM »
Nice write up!

As you progress, I'd like to see a cost breakdown of the cells/tabbing wire/ EVA and whatever else you had to buy.  I think it's great you are able to scrounge so much material so far. That's always been in the spirit of this site if you ask me  :)
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oztules

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Re: Making decent solar panels
« Reply #4 on: February 10, 2011, 06:00:45 PM »
Walp,

I have no intention of dissuading you from doing as you have suggested. Many on the web have gone that way...... and are proud of their achievements

Sadly I see no future in it, and in the long run I think you would be best to buy proper panels instead if you intend on using them for power, rather than fun.

There is an enormous amount of time that goes into making the cells ready to mount in the first place. At that point you get to chose how long you wish to see your efforts produce effective power.

If is just for a giggle, to see how it works, and educate yourself, then it is all worth it, even if you only use sticky tape on the back of a sheet of glass to mount them. It is uplifting to see the sun turn into power.......

However, if you want the things to last 25 years or more, then you must look at it differently. There are only 2 ways I have discovered to allow us to get good results electrically, and mechanically over that time period. The Sylguard is a simple and effective way  (and darn expensive), but I don't have any results to point at to say how long this system has actually lasted. I suspect it is as good as the EVA approach..... but I have no proof.

Eva onto toughened glass has a track record, and most folks know of panels that are at least 1/4 of a century old and still running fine. The EVA of today is better than the EVA of yesteryear, and will be less likely to change colour than the older material. I have some BP panels 15 years old, which have clearly changed to a brownish tinge over the cells... from the heat, not the UV alone. The intercell spaces are still clear, as are the last 1/2 inch of the outer perimeters of the cells.... but even then, the performance is probably only 10% less than stated on the stickers.

If you build the panels for 50c per watt, and they only last a few years.... then it would have been cheaper to buy them made.... as they should have lasted at least 12 times longer.... so to keep replacing is $6.00/watt......??

You can still use your plastic with the EVA, just keep the temp low, and it will work just as well. Cooling is difficult with sealed box arrangements, and your output will reflect the fact that you will be building a solar heater..... with them inside where the water usually is (solar hot water ).


Volvo.

The oven was free, the tyvec was left over from a building project (house wrap). I put the call out for solar hot water panels... I now have had 20 delivered..... thats 4kw... and more coming I believe..... all free.... don't know what I'm going to do with them all....

So the glass is toughened and iron free, the panel frame is aluminium... comes with the glass, and all the rubber fittings etc. Just need to cut vent holes in the back for convective cooling... the only cost is the cells ( somewhere around 40c/watt from memory.... I bought 2kw of cells from the USA for $950 delivered to here.... they were supposed to be short tabbed, so the vendor gave me $150 bucks off if I kept them rather than returning and replacing them.... so about $800 for 2.2kw (he sent a heap extra). This included 1000 feet of tabbing wire and some 100 feet of bus wire..... so that was included, as were the flux pens.... Fredv8 or something similar on ebay also has tabbed ones for only 38c/watt for those folks in the USA. I got mine fromJeff at  MLSOLAR... good bloke.

The heater was free from the tip (dump), and the vacuum pump was from China (about $150 delivered) The EVA was from China, about $550 for 60 meters (enough for over 3kw).... about 19c/watt.
 If we amortize the pump over the 2kw we see about 7c/watt

Looks like this:
Cells          .40
EVA           .19
Pump        .07
Thus,  for cells we can expect to last the same as the commercial ones, it comes to around $0.66/watt.... complete with enclosures.


Without the defunct solar water panel, this would not be possible, (glass and aluminium) but the doors you used would fit the bill ok, and any kind of frame you felt like using to match..... and you would have gotten 2 panels instead of 1 per 2 pieces of glass in your case.


.............oztules
« Last Edit: February 10, 2011, 06:11:27 PM by oztules »
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Volvo farmer

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Re: Making decent solar panels
« Reply #5 on: February 11, 2011, 06:41:01 AM »
Oz, have you actually put your panels out in the sun yet and checked the power output?  I built my panels with the exact same looking cells, but more of mine were chipped/cracked or off-color than the ones appear to be in the current auctions.  Anyway, my point is, that I built 72 cell panels, and have never seen more than 3A@26V out of any of them.  On a nice cold winter day at noon, I'm seeing around 10 amps into 24V nominal batteries out of 288 cells.  So the auctions I looked at were advertising these as 1.8 watts/cell and I am observing somewhere around half that.  I believe my cells were rated at 1.5 watts-per-cell, because I was expecting to build 100 watt panels.

While we both agree about whether this is a cost-effective way to make solar electricity versus manufactured panels, I am curious if your cost per watt might be somewhat low because of using the stated watt/cell in the auction. rather than a measured figure.





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ghurd

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Re: Making decent solar panels
« Reply #6 on: February 11, 2011, 07:44:46 AM »
Looks Great Oz.

What VF said.
Most companies test and sort the individual cells.  A couple weak cells in the string will hold back the output.

For a while, one company I dealt with had 70, 75, 80, 85, and 90W panels with "the exact same parts".  Had to look at the sticker to tell what it was.
The lower grade cells went into the 70W.  Highest into the 90W.

The good thing for me was the 75 and 80W were the best $/W, but they sold fast too, so when I ordered large quantities they never had enough 75/80W and always sent 85/90W for the same price.   ;D
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DamonHD

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Re: Making decent solar panels
« Reply #7 on: February 11, 2011, 08:53:21 AM »
When I selected my grid-tie PV I asked for the highest-grade panels of the type I liked in the hope that they were actually the 'or over' category.  Generally they have performed above expectations, so I may have been right.

Rgds

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dave ames

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Re: Making decent solar panels
« Reply #8 on: February 11, 2011, 11:34:53 AM »


cheers oztules,

this is a topic i swore i'd never revisit.

it's heartbreaking to see ones hard work go to bits like a turd in the rain.  :'(

but now a tasmanian devil hints at the possibility of achieving clean room results with backyard caveman equipment ..we have to pull up a desk and get out the scratch pad.

following along here in the back row,
kind regards..dave  kb1mzf


phil b

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Re: Making decent solar panels
« Reply #9 on: February 11, 2011, 11:48:19 AM »
Hi Oztules
I'm glad to see your posts on solar panels. I too, have had limited success from making solar panels. Mine lasted a few years in a wooden garage door frame. The output progressively got worse with time. Still, for my money, I'll buy them.
I am currently attempting to encapsulate LED modules into groups of 24. I want to use them outdoors and on emergency vehicles for non-commercial use. I'm thinking the EVA may be something to experiment with...if I can find a good reputable company to deal with. Smooth-on's crystal clear pour on stuff offers promise, but it is expensive.

I'm looking forward to your next write up. Excellent and thanks.
Phil

oztules

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Re: Making decent solar panels
« Reply #10 on: February 11, 2011, 05:17:01 PM »
"Oz, have you actually put your panels out in the sun yet and checked the power output? "...... is this a trick question?

I suspect that you...... like me dragged your newly built panels out into the sunshine lickety split..... the moment you could move them.....

From experimentation here, I would expect around the 3 to 3.3A for cells under heavy glass like you have used, so am not surprised with your figures. Mine runs at around 6-6.5 amps for the single 2mx1m panel.... only marginally better than yours

It is currently used in a solar pumping setup, where V is fixed at 34v..... into a curtis 1204 series 270amp controller so it does produce  over 200W for the 138 cells (supposedly 248W). When clamped at 34v, it runs about 220w (6.5A x 34v). Your load is the biggest thing with solar watts, If I clamped it to a 24v bank, then the figures would be as you say (6.5x 26=170w) or a flat bank would look worse (22x6.5... 140w)
 
The cells were rated at 3.6A, but (measured and sorted them out) most were 3.8A and over. The solar glass is fairly thin (3mm or so) and iron free, so this may help considerably in getting closer to the rated power output. The other thing with the EVA is that the cooling is much better than other methods of encapsulation. A cool breeze helps keep the temp down.... front and back.  If they are double glazed etc, then this is not available to the cells.

Your 3 amp at 26v pretty good for a 72 cell configuration........ considering your glass thickness and type. What your really saying is 3A@ 36v....(max power point) so your nominal 100w is about right on the money. It would appear that if you matched the load, you would have your 100w

If the 3A is coming out of an mppt electrickery load matching gadget, then I would be disappointed.



............oztules
Flinders Island Australia

oztules

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Re: Making decent solar panels part 1
« Reply #11 on: May 02, 2011, 04:57:51 AM »
As time has moved on and kilowatts of panels have now been made, a correction needs to be made to the heating profile mentioned in the write up

From above this was written
"The heating profile I will use is like this:

15 mins at room temperature with full vacuum
15 mins at 65C with full vacuum
70-80 mins at 100C (or thereabouts with full vacuum"

However, it has been found that on larger cells, the prevacuum at room temperature was a problem. With large cells, the metal tab on the front will try to take the pressure of the air when the vacuum is pulled on. It can then try to push the tab wire into the eva, to spread the pressure load. When the air temp is cold, the EVA won't give easily enough, and the silicon cell will try to wrap around the tab wire so it can press against the eva as well.......not being flexable, it will instead split along the tab.

This is easily mitigated by raising the temp up to 50C or more (less than 65C though) for the prevacuum, rather than room temp.

I found room temp fine on a hot day, but too cold at night...... so now use the oven to get 50c. This softens the eva, and makes it easy for the tab wire to sink into the eva, so the silicon presses evenly against the "glass".

So it now should read
"The heating profile I now use is like this:

15 mins at 50C-60C temperature with full vacuum... but not melted at this stage
15 mins at 65C with full vacuum
70-80 mins at 100C-120c (or as much as you can get without compromising the plastic vacuum bag. 140C max) or  thereabouts with full vacuum"

The higher the temp (but still less than 140C) the faster it cures, and the glass bonding happens faster too.



...............oztules
Flinders Island Australia

conntaxman

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Re: Making decent solar panels
« Reply #12 on: August 21, 2011, 09:20:06 PM »
Walp,

I have no intention of dissuading you from doing as you have suggested. Many on the web have gone that way...... and are proud of their achievements

Sadly I see no future in it, and in the long run I think you would be best to buy proper panels instead if you intend on using them for power, rather than fun.

There is an enormous amount of time that goes into making the cells ready to mount in the first place. At that point you get to chose how long you wish to see your efforts produce effective power.

If is just for a giggle, to see how it works, and educate yourself, then it is all worth it, even if you only use sticky tape on the back of a sheet of glass to mount them. It is uplifting to see the sun turn into power.......

However, if you want the things to last 25 years or more, then you must look at it differently. There are only 2 ways I have discovered to allow us to get good results electrically, and mechanically over that time period. The Sylguard is a simple and effective way  (and darn expensive), but I don't have any results to point at to say how long this system has actually lasted. I suspect it is as good as the EVA approach..... but I have no proof.

Eva onto toughened glass has a track record, and most folks know of panels that are at least 1/4 of a century old and still running fine. The EVA of today is better than the EVA of yesteryear, and will be less likely to change colour than the older material. I have some BP panels 15 years old, which have clearly changed to a brownish tinge over the cells... from the heat, not the UV alone. The intercell spaces are still clear, as are the last 1/2 inch of the outer perimeters of the cells.... but even then, the performance is probably only 10% less than stated on the stickers.

If you build the panels for 50c per watt, and they only last a few years.... then it would have been cheaper to buy them made.... as they should have lasted at least 12 times longer.... so to keep replacing is $6.00/watt......??

You can still use your plastic with the EVA, just keep the temp low, and it will work just as well. Cooling is difficult with sealed box arrangements, and your output will reflect the fact that you will be building a solar heater..... with them inside where the water usually is (solar hot water ).


Volvo.

The oven was free, the tyvec was left over from a building project (house wrap). I put the call out for solar hot water panels... I now have had 20 delivered..... thats 4kw... and more coming I believe..... all free.... don't know what I'm going to do with them all....

So the glass is toughened and iron free, the panel frame is aluminium... comes with the glass, and all the rubber fittings etc. Just need to cut vent holes in the back for convective cooling... the only cost is the cells ( somewhere around 40c/watt from memory.... I bought 2kw of cells from the USA for $950 delivered to here.... they were supposed to be short tabbed, so the vendor gave me $150 bucks off if I kept them rather than returning and replacing them.... so about $800 for 2.2kw (he sent a heap extra). This included 1000 feet of tabbing wire and some 100 feet of bus wire..... so that was included, as were the flux pens.... Fredv8 or something similar on ebay also has tabbed ones for only 38c/watt for those folks in the USA. I got mine fromJeff at  MLSOLAR... good bloke.

The heater was free from the tip (dump), and the vacuum pump was from China (about $150 delivered) The EVA was from China, about $550 for 60 meters (enough for over 3kw).... about 19c/watt.
 If we amortize the pump over the 2kw we see about 7c/watt

Looks like this:
Cells          .40
EVA           .19
Pump        .07
Thus,  for cells we can expect to last the same as the commercial ones, it comes to around $0.66/watt.... complete with enclosures.


Without the defunct solar water panel, this would not be possible, (glass and aluminium) but the doors you used would fit the bill ok, and any kind of frame you felt like using to match..... and you would have gotten 2 panels instead of 1 per 2 pieces of glass in your case.


.............oztules

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oztules................. You should take a break from putting people down.You most likely couldn't make a panel. yuck, some people.

Tritium

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Re: Making decent solar panels
« Reply #13 on: August 21, 2011, 09:53:55 PM »

oztules................. You should take a break from putting people down.You most likely couldn't make a panel. yuck, some people.

I predict a severe rebuke from the long time list members for that remark with only 3 post here to your name.

Thurmond

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Re: Making decent solar panels part 1
« Reply #14 on: August 22, 2011, 03:38:47 AM »
con,....you obviously haven't read parts 1 ,2 ,3 ......seems Ozutles is the go-to guy if you're thinking of making solar panels...
I agree with Thurmond........you'll probably get flamed for such a stupid remark.....artv

TomW

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Re: Making decent solar panels part 1
« Reply #15 on: August 22, 2011, 08:02:30 AM »
conntaxman;

Pull your cranium from your anus.

Oz has been here forever and he has made panels.

Any more of this and I will petition the mods to put you in the read only room for a year.

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Join in an alternative forum at Anotherpower.com

TinnerD

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Re: Making decent solar panels part 1
« Reply #16 on: December 06, 2012, 08:45:25 PM »
I like all the input here, as I am building an addition to my barn with extra space for a Solar Work-shop. I will soon have the expansion in the dry, so I have been searching for good suppliers for cells and encapsulation material with no luck.
I have heard horror stories from others with e-bay auctions.
Any help would be deeply appreciated.

conntaxman

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Re: Making decent solar panels part 1
« Reply #17 on: December 06, 2012, 10:43:40 PM »
TinnerD . Try buying from people in the UAS. and try not to use "split or broken" cell.
you will see that they are cheaper, but they sure are not worth it.I have make mine and so far they are on the 4 year mark and still running strong. Also try to buy a MPPT controller, that will get you a little extra power from your panels.
Good luck and have fun,nice to see someone build a panel.
Their are many that will put you down for DIY panels, don't let that bother you.
John

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Re: Making decent solar panels part 1
« Reply #18 on: December 07, 2012, 11:31:57 AM »
OZ,

Really "AUSome" write up!  I enjoyed the read very much. 

I noticed your mention of Sylgard.  I do believe that this is how it is spelled and it is a Dow-Corning product.  I used to use this quite a bit in the aviation field for weather radar aboard aircraft.  It serves as an electrical insulation and moisture barrier potting compound for the magnetron's high voltage power leads in the RCVR/XMTR unit.  It prevents arcing and corona around the terminals when the aircraft is at high altitude.

I was looking this up not too long ago and it is called Sylgard 184 and runs about US $350 per ~3 quarts??? (4 Kg), maybe more expensive by now.  When you mix it up (it is a two part elastomer product), there are thousands of tiny air bubbles in it and it has the consistency of flowable silicone rubber sealant. 

We would mix up a small batch and pour it into the area around the HV terminals of the transformer in the unit and put the entire radar RCVR/XMTR unit in an altitude chamber and pull a vacuum on it, pumping down the pressure or upping the vacuum slowly - however you want to look at it.  We would basically simulate the conditions at 52,000 feet of altitude.  The air bubbles would boil out of the Sylgard until it was perfectly clear.  Then we would bring the chamber back down to sea level (or ground conditions) and remove the RCVR/XMTR from the chamber and put it in just a regular home kitchen stove (oven) with the temperature control hard set to 200F for X amount of hours to cure it.

The end result was a perfectly clear, untinted, unshaded block of "silicone-like" rubber with zero bubbles.  It was so clear that if it were 30 foot thick, you could see through it just like pure, clear glass.

Which brings me to a question for you.  You mentioned "IRON FREE" glass.  I don't know what the reason behind this is.  Why is this important?  Is it the translucency of the glass?  The clarity?  Or some other property that would block certain wavelengths / UV? 

Thanks OZ

RADAR 

PS  I don't intend to go out and build panels for myself, I just want to learn all about them and the theory so I know better how to buy them and treat them after I get them.
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fabricator

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Re: Making decent solar panels part 1
« Reply #19 on: December 08, 2012, 11:55:34 AM »
TinnerD . Try buying from people in the UAS. and try not to use "split or broken" cell.
you will see that they are cheaper, but they sure are not worth it.I have make mine and so far they are on the 4 year mark and still running strong. Also try to buy a MPPT controller, that will get you a little extra power from your panels.
Good luck and have fun,nice to see someone build a panel.
Their are many that will put you down for DIY panels, don't let that bother you.
John

WTF is your problem? You do of course realize that OZ wrote parts 1, 2, and 3 of this series right? Get a clue pard.
I aint skeerd of nuthin.......Holy Crap! What was that!!!!!
11 Miles east of Lake Michigan, Ottawa County, Robinson township, (home of the defacto residential wind ban) Michigan, USA.

oztules

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Re: Making decent solar panels part 1
« Reply #20 on: December 08, 2012, 03:16:13 PM »
Radar,
As best as I can recall, you need to do a little of quantum mechanics to understand the why for how light transmission through objects works.

Simply put, all matter is made up of mostly nothing. The proton in a hydrogen atom if viewed as the size of a basket ball, would see the electron cloud some 20 miles away..... it really is hard to hit something if your just passing through.

If the energy of a wavelength of light does not match exactly with one of the quanta levels of the outer electron shell/s of the substrate (glass in this case), it will in all likely hood pass straight through, and miss the nuclei and everything in the glass.

However, if the energy level of the wavelength matches one of the quanta levels that the outer electron layers can absorb/use, it will be absorbed, and then the energy re transmitted as color etc... and the  energy level falls back to "normal". In this case, the wavelength was intercepted, and the photon did not pass through, and so the substrate was not transparent to this wavelength, but in fact interacted with it instead.

An example would be normal sunlight passes straight through glass, but the higher energy wavelengths (ultraviolet and up) have an energy level that will interact with the glass atoms, and so in practice it is hard to get sunburned behind glass, as compared to no glass... To UV the glass is not seen as transparent.

The iron atoms in the glass alter the energy levels of the  shared electron shell/s it is involved with and so  can now  intercept some of the useful wavelengths and so steals some energy that would otherwise have passed through the glass into the solar cell itself.

Thats what transparency is, and why  photons with a wavelength in the white light spectrum can pass through the window and show you whats outside.


well, thats as I understood it from years ago.....



...................oztules

Edit: Conntaxman, my home made panels have made around 6000000whours (6MWH) in the last 12 months. Home brew panels can indeed work.
« Last Edit: December 08, 2012, 03:31:08 PM by oztules »
Flinders Island Australia

AcWxRADAR

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Re: Making decent solar panels part 1
« Reply #21 on: December 09, 2012, 10:18:37 AM »
Oztoules,

Well understood.  I was correct in my assumption that it had to deal with the "transparency" of the glass for specific wavelengths.  However, I had never heard of Fe free glass.  I  have, of course, heard of leaded glass, but not much more on the subject than that.  So basically, any impurities in the glass, Fe, Pb etc would not be desired and the ideal glass for PV panels would be impurity free.  That has to be an art and a science in itself to create the protective glass to optimal optical standards AND THEN make it strong (impact resistant) as well!  I am sure that you must give up one thing for another in this endeavor.

Thanks for the knowledge, hoping to learn some more!  :)

RADAR
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Clyde "FATS" Potter from "The Cowboys"

JW

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Re: Making decent solar panels part 1
« Reply #22 on: December 05, 2016, 07:20:07 PM »
The topic should be sticky now, let me know

vpdavid

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Re: Making decent solar panels part 1
« Reply #23 on: September 04, 2017, 05:15:35 AM »
Thanks for these technical implication of solar creation, I had never thought that it could be possible to understand for me.

oztules

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Re: Making decent solar panels part 1
« Reply #24 on: September 09, 2017, 08:18:25 PM »
This is a simplified rendition of what happens and will do for having a working theory for explaining the results you will see in the real world.

It is not however a proper explanation of the quantum mechanics that actually happen... it is way too counter intuitive and complex to bother with in this circumstance...... eg an atom of hydrogen is best explained  as  being a proton with a electron in orbit around it... it will do for most purposes, but is so far from the truth as to be laughable really.... but that picture is what we are told unless we need to know one hell of a lot more.... and that requires virtual particles, and a whole lot of unbelievable things going on all at once.

It will do for the time being though.

......oztules
Flinders Island Australia