Possible encapsulation material?

[Calgirl]

[QUOTE=Jeffc;18257]From Datasheet-

POLYSULPHIDE SEALANT is a one component, gun applied, synthetic rubber based sealant which cures by absorption of atmospheric moisture to form a permanently flexible seal. It is suitable for use within the construction industry on all joints where above average repeated movement is encountered over a wide temperature range. It provides outstanding resistance to weathering and chemical attack from solvent, alkalis, dilute acids, oils and grease.

This is the stuff that is used to seal double glazing units.


How about applying a bead of this around the perimeter of each cell onto the glass. Notice it cures by absorption of atmospheric moisture so any moisture between the cell and glass will be absorbed in the curing process.

Here is a link to the data of a product sold in UK.

http://www.kingfisheruk.com/specs/data/polysulphidesealantpds.pdf

It has very good U/V resistance and 20+ yrs service life. Oh and it

[russ]

I asked the pu man to comment if he would - he may have some insight into the product.

RUss

[Calgirl]

Have you ever worked with sylgard???? I have and it's a very thick substance.
I don't think you could coat them and hang them up to dry. and the wireing would be weakend also. Good luck to you if you can do that..Why don't you put the sylgard down then put the cells down then cover the rest with the rest of the sylgard. do this all at once. O Don't forget the backing.

You are quite correct that I have not built any panels, however, I have two panels, which have been soldered and are ready for encapsulation. I halted the panel building process when it became evident that my planned process to protect the cells and wiring was not adequate.

I will soon see if your suggestion that the Sylgard solution is too thick (heavy) to cover the cells by dipping, or that hanging the string to dry would destroy the soldered joints or harm the tabbing. I suppose that the quality of the soldering workmanship has a large impact, along with the weight hanging on the tabbing wire, and whether you manhandle the string. Your suggestion of laying the cells down on the encapsulant still has the problems with possible bubbles, but my guess is that it is better than pouring it on.

Since cost per watt is a consideration, the dipping process uses less encapsulant while completely covering the cells and wiring than hoping that the encapsulant seeps under the cells without any bubbles! If we can get more than one panel out of a given amount of encapsulant, then we are ahead. Since my three containers of Sylgard just arrived two days ago, I will soon have preliminary data. My expectation is that my proposed process will improve the longevity of the panels if it works, but of course, only time will tell.

[Jeffc]

Sounds interesting, although a "bead" may not be enough to completely absorb moisture, etc. Since it is cheaper than Sylgard, it might be cost effective to pour or paint it on. If you give it a try, I'd be interested to read about your preliminary results.

Because it is applied with a mastic gun , I don't think it can be poured or painted on.
I plan to bead around each cell (using weights to press cell to glass, there should not be much air between.)I will seal 3 sides of each cell then use hairdryer to heat and expell moisture then seal fourth side.I will allow to set before I coat the rest of the cells.
If I do it all at once I run the risk of the sealant contaminating the front of the cell as the sealant is not clear.I think white would be best so as to absorb less heat.I will test first on some broken cells. Be aware that polysulphide can react badly with perspex and the like so glass is best.

JC.

[Davidson]

encapsulation without front glass

This product would give far better UV stability over a standard Epoxy clear system agreed however if you check through the data it is a rigid system - a major no no. If you used this type of system during cycling it would crack and probably crack the cells as well. Any encapsulant used needs to have flexibility so that it can expand and contract without causing stress fracture.

I was thinking of Smoothon Clearflex 95, having 95A hardness.
put the solar string in a mold and fill the mold with this clearflex.
It's hardnees is not that high - so it will not crack.
It has no sticky finishing like the clearflex 50, so you don't have to put glass on it.
what do you think PU man?

[solarrules]

I came across this forum while looking for a cheap way of encapsulating my panels.---Glad I did!

]

Check out this post where Rolland is trying to get enough DIYers together for a bulk purchase:

http://www.solarpaneltalk.com/showthread.php?3246-Slyguard-184-encapsulant-for-half-price.-Anyone-interested-in-a-bulk-order

It's roughly 1/2 the cost of Sylgard and perhaps better

[the pu man]

Sorry All been out and about for the last few days. Ok looking through posts so far:

grayski41 - The use of the xylene I guess is simply so you can thin down on the viscosity of the silicone and make it go a little further. Nice idea but xylene is particularly nasty. I cant really see the benefit of using the xylene as it will potential eat into anything it touches bar glass. Has someone actually suggested you do this? I have never heard of using xylene on a two part system. Yes you can use it on a one part as essentially you are just adding it to thin it down - the xylene and moisture or other solvents evaporate to leave the cured silicone but 2 part systems do not cure like this!! The xylene may flash off but it would degrade the silicone. If it gets locked into the silicone 2 part then you would end up with a horrible mess.

Jeffc - Polysulphide Sealant is as you rightly suggested used for glass bonding. I think it was originally developed for windscreen bonding. They are a one part system and they absorb moisture in order to cure. I believe you could use it to cover the cell backs however suggest you check out the information prior to using problems I can see are:
1. 14 - 28 day cure - You would have to leave the panel open to the atmosphere for this period to get the required product
2. Minimum thickness of application is 6mm. Do you really have this sort of depth or are you actually looking at a coating thickness closer to 2 - 3 mm.
3. Refering back to use of differing materials you run the risk of a bond line failure between the encpasulation for the cells - clear silicone and encapsulation for the back polysulphide. I doubt you would get adhesion between the two. This would allow a direct water path between the two materials.

It could well be that this product could be used as an edge sealing system for the panel, just like you would use it in double glazing or windscreen appplications.

Just to give everyone an update we are now in the process of testing and evaluating one of our PU system. We are working with a company called Know your planet in the UK who are already set up to market parts for solar cell manufacture. It is going to be around 3 months until we launch the product to market as we have to run UV chamber tests on actual finished panels. We will try to keep everyone updated as we progress and we intend to post videos etc on the net. One of the major benefits we can already see, other than being in the region of half the price of the sylgard is the viscosity. It is currently like single cream in viscosity so it has massive flow benefits. One thing we are tyring to ensure is low toxicity. Most PU clear systems use a toxic ingredient on the Part A side. Please if anyone does try other PU systems watch out for the skull and crossbones symbol - believe this will be different in the US as they now have differing labeling to the rest of us. If you do see anything that says toxic by inhalation make sure you work with it in a well ventilated area. This goes for Grayski as well Xylene is not nice so stay safe.

Sorry missed you out Davidson - If I understand correctly you are going to pour in a coat of the product into a mould, let this cure, place the cells in position on the coat and then pour a second coat to totally encpasulate. Then you end up with a semi flexible mat of encpasulated cells? Are you going to put this into a glass housing or just then use it as a finished panel? I like this idea and its out of the box. Why do we need to focus on glass bonding and sealing when you could actually do this. The downsides for you are that using the 95 A the mat would be flexible and solar cells are extremely brittle and liable to crack with any flex of the mat, just a small amount of movement would run the risk of breaking the cells. I might try this one but actually use a rigid system. If you could produce a panel in this method producing a rigid encapsulated panel without glass you would significantly reduce the materials used and the problems of moisture absorbtion. You could even make panels which were shaped to a surface, why does a solar panel have to be flat? Time to contact the patent office I think!!

[wayhopper]

Shipment:

Rolland, what is the status of the shipment? Is there an official shipping number yet?

wayhopper

[longwolf]

Update

Hi guys!
Wow, I come back to give an update and see that we've been stickied.
Kinda makes ya feel special, lol

I haven't been to the site in a while because of another project. I've done a waste oil conversion on my old diesel van and I'm happy to report that I've now driven about 100 miles running on WO
I'm still living in the van so the pre-filtering setup must be powered by the van. It uses a 500 watt, home made centrifuge. So i kinda need to make another panel or two soon.

Anyway, to recap, last July I built a solar panel using Clear Seal. It's made with 6' by 6' cells and is 58.5' by 27.25' and took about $24 worth of CS. It has 8 interlaced bypass diodes. I thinned the CS with mineral spirits and did the pour in two steps, which turned out to be a mistake. It caused several bubbles, some large, and I cracked a few cells while I was at it. Despite that, the panel tested out with 20.3 volts at 7.6 amps at noon on a summer day. After it had dried for a couple of months, I covered the back with Reynolds Wrap for added moisture protection.

So the panel has been riding on the top of the van since then. It's been through a Texas summer and winter and seen temperatures from 105 to -7 degrees. It's been through rain, freezing rain, sleet and several inches of snow. It's been driven over speed bumps, pot holes and at speeds up to 75 mph.
About 2 weeks ago I re-tested it. It was 1 PM, the panel was a little dusty and I wasn't quite able to angle it directly toward the sun. The reading came out at 20.21 volts and 7.64 amps.

So far so good

I'm also happy to report that the panel hasn't spontaneously combusted or suffered from the mineral spirits that were used.

[grayski41]

the pu man - Thanks for your comments, thinning with xylene was recommended in an online book i downloaded, im no chemist so can only go on advice, is there maybe something else i can use to thin the 2 part silicon? it is alot easyier to use when thinned down, but i guess if there was the manufacture would have done it to bulk out ther product and sell more... I think from a diy point of view a thin coating on each side of the cell opposed to total encapsulation would make any future repairs easier. i know we all hope to not have to touch our panels again once on the roof, but its not likely.. BTW good luck with your project i recently purchased some bits from Know your Planet UK very nice people,,

[Mike90250]

.....

So the panel has been riding on the top of the van since then. It's been through a Texas summer and winter and seen temperatures from 105 to -7 degrees. It's been through rain, freezing rain, sleet and several inches of snow. It's been driven over speed bumps, pot holes and at speeds up to 75 mph.
About 2 weeks ago I re-tested it. It was 1 PM, the panel was a little dusty and I wasn't quite able to angle it directly toward the sun. The reading came out at 20.21 volts and 7.64 amps.

So far so good

I'm also happy to report that the panel hasn't spontaneously combusted or suffered from the mineral spirits that were used.

Good News, thanks for the update

[charlie_ruizpr]

Hey longwolf, How many ounces of liquid nails clear seal will I need for a 108 cell panel?

[rollandelliott]

there are many encapsulants out there that are not that expensive

slygard 184 do is what everyone complains about becuase it is expensive and has air bubbles.

but there are 4 other solar encapsulants:
dow 6010 around $36/kg
Elastosil 2202 unknown price
EpicResins d9940 $7/kg
qsil 216 around $25/kg

just do a google search for solar encapsulants and you can get more info, the companies might even send you a free sample if you ask nicely.

the reason people do NOT use these encapsulants is some have minimum orders of over $1000.00

[longwolf]

Hey longwolf, How many ounces of liquid nails clear seal will I need for a 108 cell panel?

That's hard to say. My panel was a little less than 1600 sq inches. It's been a while but I believe I used 7 of the small tubes that Walmarts sells. That was enough to glue the glass to the frame, make a dam around the cells then do the pours. I think the tubes were either 5.5 or 6.5 oz each.

[longwolf]

slygard 184 do is what everyone complains about becuase it is expensive and has air bubbles.

but there are 4 other solar encapsulants:
dow 6010 around $36/kg
Elastosil 2202 unknown price
EpicResins d9940 $7/kg
qsil 216 around $25/kg

just do a google search for solar encapsulants and you can get more info, the companies might even send you a free sample if you ask nicely.

the reason people do NOT use these encapsulants is some have minimum orders of over $1000.00

Wow, those look like some good prices.
Do you know which will do small orders?
Will the EpicResins d9940 stay flexible?