Vacuum sealing solar panels

brenneis · April 2009

Hello, I am in the process of building my own solar panels. I am currently sandwiching the cells between a thick acrylic plastic on the bottom and tempered glass on the top with silicone around all the edges.

The professional panels say that they are vacuum sealed at the factory, however on some DIY sites it states to ensure you drill a hole in the bottom to allow for moisture to escape.

I have figured out a way to vacuum seal my panels cheaply by using my foodsaver vacuum sealer. The machine has an attachment where you can connect a piece of small hosing to vacuum seal a plastic container for food. I stuck a piece of the tubing between the two panels and siliconed the whole thing in. Then after drying vacuum sealed it (you can hear an audible pull on the machine when it has sucked out all the air). I then clamped it right at the base of the glass, cut about an inch off after that and filled the tube with silicone. After drying, I released the clamped and presto I had a vacuum sealed panel. It also helped me find where if any there were any leaks in the seal I made around the panel edges which I can only assume will prevent headaches down the road with weather.

My question is, is this advisable.....ie, will moisture still develop???? do you need an air outlet.......thanks Brian

BB. · April 2009

Re: Vacuum sealing solar panels

Sorry brenneis,

This post was also stuck in the "Moderation Queue" for the website announcement forum. Need to put posts in (approximately) correct sub-forum for people to see and reply too.

I moved this one to the beginner's corner.

We are not trying to ignore you--we generally don't check the Announcement sub-forum for posts from non-admins.

Regarding building your own solar panels... Typically, we try to direct people away from building their own solar PV panels as it is not (usually) cheap and the panels will probably not last very long when mounted in the weather (months or a year--instead of the 25+ years for a well made production solar PV panel from a reputable vendor).

It appears (no details yet--but guessing from what we have seen so far), from this thread, that large home built panels when wired together into kWatt sized arrays may even be a significant fire hazard.

Regarding your question--if you can get a 100% hermetic seal--then you should not need to drill any weep holes in your panel...

However, it is standard practice for almost any electrical/electronic weather enclosure to drill a weep hole or two at the lowest point to allow water to be expelled (as it is very difficult to get a hermetic seal on home make and/or enclosures).

You could try using your panels without a weep hole and see what happens... If you see moisture buildup / condensation under the glass during normal operation--you could always add a weep hole later (assuming it is easy to get to the panels and drill).

And welcome to the forums!

-Bill

mike95490 · April 2009

Re: Vacuum sealing solar panels

brenneis wrote: »

My question is, is this advisable.....ie, will moisture still develop???? do you need an air outlet.......thanks Brian

A food bagger will not get much of a true vacuum. But you likely got enough air out, that you wont get much condensation for now. Because water vapor moves thru silicone caulk, (that's how it cures), in several months, you will have water & air back in there. If you had potted the whole thing in epoxy and used a vacuum bag, as used for carbon fiber layup, that would have driven epoxy into all cavities, and lasted much longer. So enjoy the "fog free glass" while it is fog free. When it fogs up, then you will have to drill vent holes, both top & bottom edges, on the rear (acrylic) side. May as well use the hot air convection to help dry it out.

brenneis · April 2009

Re: Vacuum sealing solar panels

I am learning the hardway that I may have bit off more than I bargained for with building these things. It actually started more as a home project because I got tired of building model planes and figured why not build something to offset my energy costs....and it has indeed been fun. As to how long they will last and how great they will be in comparison to professional ones....well, I guess I shall find out............it seemed much cheaper but it seems everytime I leave the house I end up at home depot buying more crap to complete one of these things and get a system down. So with that said, since I now have the makings of panels that I don't want to go to waste....can anyone provide any good tips, or must do's to try and make these things last....I am particularly concerned with condensation issues and mounting or reinforcement of the panel to help prevent warping and flexing in the weather......

I still have a lot more roof to go and the panels I am building are only covering the exposed shed.......after this I am coming to you guys to have professionally made ones shipped..

brenneis · April 2009

Re: Vacuum sealing solar panels

this idea stinks....don't try it.....my vacuum worked for one night and then the air seeped back in somewhere....

System2 · May 2009

Re: Vacuum sealing solar panels

Hi every one. My name is Joe. This is my first post and i am probably posting in the wrong section. Sorry if this belongs some where else.
I have been doing allot of research on making my own panels. I am, along with allot of you stuck at the lamination part of the process. I did not want to just make a wood frame and watch all my cells corrode and fall apart from not finishing my project the right way. This has led me to combing all through the world wide web. The only thing that is keeping me from making professional panels is a laminating machine. I can buy the lamination materials but i have no machine to finish. So what do i do? well the obvious thing to me is make a lamination machine. I called a few manufactures of different machines just to pick there brains and find out the costs of buying a machine and what i can manufacture panels for if i had 33,000-58,000 to buy their machine. What i was quoted was about 2.00$ to 2.50$ per watt! You cant buy panels at that price even if you buy panels by the mega watt. I have a building that has an electricity bill of 3,000- to 6,000 per month,and i got a solar quot for a million! If i could make panels at two bucks a watt and get a rebate of 1.22$ per watt even if i bought a professional machine for 58,000 i would still come out way ahead. My dilemma is i don't want to pay that kind of money for a huge waffle iron with a vacuum attached to it. I have a friend who is an engineer that said he could build one for me for a fee, but to save some money i wanted to build my own very low tech version first and then have him make it better. If i could make my own diy machine i would want to share the plans with every one so there would be a small business machine on the market like one or two machines i saw on youtube that the Europeans and the Canadians have made in there little workshops. sorry for the long drawn out post but i think as a large group of do it your selfers with a passion for solar and clean energy we should all put our heads together and come up with some plans for the missing puzzle piece a low tech lamination machine. I have found some specs and some info on how exactly a lamination machine works here is one little tidbit that i found and will dig up and post more if any one is even remotely interested in this post.
http://www.strsolar.com/en-us/resources/Documents/photocap_technical_manual_rev2.pdf

STR PhotoCap Solar Encapsulants
Thanks if you actually read my whole post.

dwh · May 2009

Re: Vacuum sealing solar panels

jobeythatsme wrote: »

If i could make panels at two bucks a watt and get a rebate of 1.22$ per watt even if i bought a professional machine for 58,000 i would still come out way ahead.

Can you get the rebate with non-approved (UL Listed) panels?

BB. · May 2009

Re: Vacuum sealing solar panels

You can vacuum laminate by placing into a plastic bag--sealing, then removing the air. If you are "baking" the entire panel--you would have to find a "bagging material" that withstand ~80 C--the temperature used for some commercial panel lamination (depends on your materials).

Regarding building your own--you would not be able to get the rebates (requires commercially built PV panels) and your electric code/building department/insurance company would not allow non-NRTL approved (i.e., UL approved) panels to be installed on your home either.

Plus--it is not safe. See the Panel Fire thread for an example of a non-UL approved set of panels installed in a Grid Tied system (installed by a licensed contractor and inspected / approved by building department--the inspection did not catch the non-approved panels) in Southern California--which, very luckily, did not burn down a home.

Price wise, PV panel costs are falling. You can easily find panel below $4.00 per watt, and over-runs / blemished / close-outs at $3.00 per watt or even down to $2.48 per watt (just checked their page today--note; shipping/insurance costs are not cheap for solar panels--check before you buy).

Commercial panels will last 25+ years, are built from low iron tempered glass, etc.... Home made panels just will not compete.

If you are going to build your own and they are high wattage (100's-1,000's of watts in your system)--make sure you mount them over a fire resistant surface (bare ground, concrete) and not on your home in in a brush filled field.

-Bill

System2 · May 2009

Re: Vacuum sealing solar panels

Yes you are right about the UL rating. Obviously There will be legal issues to comply with. because of your post i looked into getting a product UL rated. By using UL rated material to make panels i don't think it will be that big of an issue to make panels that will pass the test.
http://www.ul-asia.com/Template09.aspx?SiteID=2&Ref=AS-RESOURCES-FAQ-SP this website answers questions on how to get a product tested and rated. I actually thought about this a while ago as well as how to offer a warranty. If i decide to manufacture panels i would get a bond that would protect all customers who buy my UL rated panels even if i were to go out of business.

I like your input about a vacuum bag. My only concern with that idea is the material sticking to the bag and how long it would last. If we put a non stick sheet inside the bag in between the bag and the panel material i think that would work. It is already common practice to use non stick sheets in the commercial laminate machines. so i think you are on to something. Does any one have any information on where a vacuum bag that can withstand such heat as would be necessary for this process?

Thanks Joe

icarus · May 2009

Re: Vacuum sealing solar panels

"By using UL rated material to make panels i don't think it will be that big of an issue to make panels that will pass the test."

I take it you have never tried to get a product UL listed? From what I know,, it is a fairly long, involved and EXPENSIVE process. My wife is an artist, and we make (she mostly) makes lamps. We have sold these all over North America and have dodged needing UL listing by using listed components and hoping for the best,,, but as lawyers have advised there is considerable risk.

I don't think that getting PV panel listed is going to be a walk in the park.

Tony

BB. · May 2009

Re: Vacuum sealing solar panels

Here is a small PDF article on setting up a glass lamination line--probably not exactly the same as what you want--but gives a 10,000' overview.

This company makes a rubber based bag for high temperature lamination (I think) of safety glass--may be higher temperature than you would need to laminate a solar panel...

-Bill

System2 · May 2009

Re: Vacuum sealing solar panels

Thank you very much for your information and links. I am looking into the vacuum bags just waiting for an email from the company. I am also looking further into The UL rating to see just how much and how long it will be. I will let you know.

Thanks Joe H.

BB. · May 2009

Re: Vacuum sealing solar panels

You can usually find local companies that will help walk you through the "UL" inspections... For a large voice mail system (some 15 years ago), it was around $15,000 in consulting fees (IIRC) plus a few days to a week of my time.

Also, you do not necessarily use UL... The term is NRTL (Nationally Recognized Testing Laboratories). And there are others; CSA, ETL, TUV (several), etc. They need to be competent in the area that they will be listing (i.e., a toy competent NRTL would not be good for a large computer controlled rock crusher).

It is not that difficult (from my experience in computers/voice mail/networking equipment) to get approved. "Listed" may be a different issue.

You need to find the correct regulatory documents (and usually pay for a copy) that your product would fall under. Make sure you use the appropriate (trace-able) materials (Red Tags that come with each shipment of plastics/components that should be on file and cross-referenced with PO's and receivers). A mfg. line that has the required test equipment (such as hi-pot for high voltage leakage testing, with trace-ability to a lab/service one a year that it is calibrated). And a twice a year unannounced inspection of your mfg. site/line.

UL/etc. NRTL's make their living inspecting and approving equipment--and they are usually pretty helpful to get a new company/product off the ground (with fees to match). I would not be afraid of the process--but it will take some time (~several weeks to several months--as a guess) and money to get the approvals.

Probably, from my point of view--you will be working harder on making sure you reliably and profitably build a panel that will last 25 years--that part is not easy (proper materials, mfg. techniques, etc.).

-Bill

Windsun · May 2009

Re: Vacuum sealing solar panels

UL certification can be expensive, typically thousands of $ and several months.

Items that use UL approved parts in an assembly, such as a combiner box using UL approved fuses and holders, are pretty easy to get approval on, but since the panel IS the major part, I seriously doubt that it is worth it.

dwh · May 2009

Re: Vacuum sealing solar panels

jobeythatsme wrote: »

Does any one have any information on where a vacuum bag that can withstand such heat as would be necessary for this process?

Thanks Joe

If I recall correctly, there are some homebuilt aircraft kits that use carbon fiber, which is then vacuum bagged and cooked.

Here's a link I found:

http://www.berkut13.com/berkut3.htm

System2 · October 2010

Re: Vacuum sealing solar panels

Wow here, a VERY belated post to a very interesting topic. Hate to sound like a knowitall..but I do know materials, and UL, and want to build my own too! But let's review some of the past posts.....

First, for the vacuum bag I would use sheet silicone to make it, as the EVA film shouldn't stick to it, it handles a couple hundred C and can be glued with silicone. EVA is the product of a ton of research...there is no better way. Forget about drawing a "vacuum" on 2 panels of anything with the cells between them, as you'll first never get anything more than a very partial vacuum (lots of air still in it) and Second, it will leak back in over time, maybe very short time...like days. You'd have to use a ton of precise separator nubs between the sheets to keep the cells from being crushed if any kind of real vacuum was achieved, a very special impermeable edge sealer, and a powerful vac-pump to get there. Then you have to insert some kind of desiccant to absorb remaining and any leaked-in moisture over years, like the thermopane window guys do.

Next, I have seen people suggest silicone sealant for panels.....YIPES.
This can be a horror show. Only "Electronics-Grade Silicone" should be used anywhere near electronics. Standard silicone caulking or home-store stuff has acetic acid, even the fumes of which eats copper!!! So check the tube very carefully for anything corrosive (some may use ammonia too, not sure but that's bad too). Only certified electronics grade silicone anywhere near electronics.

Next...UL.
I have done UL and ETL certification of electronics MANY times. It is HUGELY expensive. Slow and requires yearly production inspections of your facilities, production test equipment and sample products!! There are yearly (actually monthly) maintenance fees too. As for meeting UL specs....forget plexi, as it doesn't come close to UL94V0, the flammability spec. MUST be self-extinguishing plastic if in electronics. Stock Lexan can't be provided to that spec but can be tested to it (more in another post).

Plexiglass...
This is a good one. I see Plexi specified in home made panels repeatedly. Anyone ever see a plexi window after 2 years sun-exposure? It's white...and under a microscope it is full of tiny cracks, or "crazing" because the UV in sunlight causes the polymer to disassemble itself, over time. You can use Lexan, specially made with UV inhibitors, which is WAY better impact resistance, more costly too, and that may last 10 years...not so sure about 25.

I really want to make my own and even may make a vacuum table to do it. I have 3 vacuum pumps that should be suitable for drawing the air out of the EVA against glass assembly. Dont think they'd work for gapped-vacuum enclosures.

Anyone still out there.
Any updates on experience?
I'm in....
Cheers!

BB. · October 2010

Re: Vacuum sealing solar panels

Well, I will post an update when I get the details... But even commercial panels from major mfg. can fail after 5 years in the sun in a moderate climate. In this case, it appears that some processing / soldering problem in/at/around the junction box is causing heating/delaminations/overheating for quite a few panels/installations.

At this point, I still will tell people that building their own solar panels is more of a science fair project--rather than a practical way of reliably generating power for years to come.

-Bill

Vacuum sealing solar panels

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