Casting solar panels in composite material

brenneis · April 2009

This should really be a different thread but you guys really seem to be on the ball so I will pose it to you as well. I asked the moderator in a separate thread but I am still not sure I am putting them in a category properly. Any, I am a DIY solar panel maker. Really just enjoy the wiring and the fact that it allows me to spend countless hours in my mancave in the basement. Anyway I have been looking for a better mousetrap to mounting them on plywood or plactic and then weatherstripping and covering with plexiglass. It is very time consuming and does not produce the greatest results.

It got me to thinking about liquid plastic....they make a crystal clear resin that dries in a mold to a very hard plasitc "unbreakable" according to the website. It can then be coated in a clear UV protectant to keep it from breaking down over time in the sun. What if you were to totall wire a working panel and then prop each one up in a mold say on small plastic spacers and then cast the whole thing in 1/4 inch plastic. I am told that with slow cure resin it puts very little stress on the object. You would end up with a very hard board of plastic with all the cells encased inside with two wires sticking out of the side. It would be totall weatherproof and easy to install. Do you think this will change the molecular properties of the power transfer though. If it is clear I don't see how it is any different than copper wire being encased in plastic....the electrons flow freely inside of it.......this whole concept fascinates me and I want to try it, but don't want to waste the money if you all think it is [light moderation to remove a point of confusion] not a good idea. thanks brian

Solar Guppy · April 2009

Re: Steam Engines?

not a good idea [light moderation]

Resins are not UV protected and will cloud up, its also flammable ... don't waste your time as all you are building is something that one day WILL burn down what it is attached to

Gooserider · April 2009

Re: Steam Engines?

I know very little about plastic resins, but I suspect that there is a very good reason why we aren't already seeing panel manufacturers using the approach you describe...

Keep in mind that many plastics are not long-term stable in direct sunlight, and will cloud up, yellow, or otherwise break down over time - and you don't get much more of a severe exposure than a solar panel...

I would be very cautious about looking at specs on any resin you are considering -

1. Is it 100% sunlight / UV stable - no clouding, yellowing or other color change, and no physical breakdown?

2. Is it thermally stable - can it take the 150+ degrees F that a panel might develop in a bright sun environment?

3. Is it weather proof against all the other environmental stresses that you are going to get on a roof top or other array location?

4. Is it highly transparent to the light frequencies that you want to collect in your cells? note that many resins get their UV resistance by adding blocking agents...

What I suspect is that you won't find any resins that both meet the needed specifications, AND are even vaguely affordable...

Gooserider

BB. · April 2009

Re: Steam Engines?

Another problem with choosing the correct materials is differential expansion...

If the resin/backing/etc. has a different rate of expansion/contraction vs the silicon cells--they will fracture at the interface--either causing connections to lift or cells to shatter.

And given the wide temperature range your panels will be exposed too (noon time summer sun to freezing nights)--your potting will probably just tear itself apart.

-Bill

brenneis · April 2009

Re: Steam Engines?

[light moderation...]...this is a forum where we can all gather and post concepts, no matter how unusual. Thinking out of the box is how new ideas and innovations become reality.

I have done some research on the below and it is very doable but it is prohibitively expensive.

1. According to the manufacturer at a major supplier near me, the resin once hardened is no more flamable than any other plastic. Ie. it will burn but it requires an intense flame in direct contact for a period of time before it will catch fire and then melts into a black goo.....like any plastic would. The problem is that it shrinks while curing and would crack the cells....it would require a UV protectant... there are many small statues near office buildings and the like on their website where sculptors use the product to caste their designs...

The other idea which is doable is a product they have which is a very hard clear rubber. It does not bend much once harded and does not shrink or produce much heat while curing. The problem is that it starts to break down at above 100 degrees which a roof could easily reach. To prevent that you must add some other chemical to the mixing process. To caste a 25 by 32 by 1/4 inch, however would run about 150 bucks in material. More than I want to spend.....there are many products on the market today in which I am sure the inventor was called a [light moderation] ... while thinking it up...

BB. · April 2009

Re: Steam Engines?

brenneis,

[light moderation by me... post no longer needed]...

Many of us have gone down the do-it-yourself route with many things in our lives. While we have learned from our mistakes--we wish to help others from making the same (and wasting time, money, etc.).

That being said--we learn more from our mistakes than from our successes (assuming we survive them

).

Sincerely,
-Bill

brenneis · April 2009

Re: Steam Engines?

I see your point.......I took it totally the wrong way...I had forgotten I even used that term in my original string...thanks for bringing to my attention. He was just calling my bluff.....

BB. · April 2009

Re: Casting solar panels in composite material

Move to own thread.

"Carry on"...

-Bill

BB. · April 2009

Re: Casting solar panels in composite material

Just a clarification around how flammable "plastics" are...

In reality, pretty much any plastic will burn if there is a source of heat. Some plastics can be "self extinguishing"--but they are not non-flammable by any sense of the word.

Even with designing computers/large phone systems... We need to a screen/solid piece of metal (or other non-flammable surface) under any electronics/plastics and/or if plastics are "exposed" we need a lip under the plastics (extending out at an angle of 15 degrees--if I recall correctly) to catch any falling flaming debris.

The way we would empirically test for flammability of plastics when building systems for the telephone companies--we would take one each of every component/circuit board/power supply/fan/etc. used in the system and conduct a flame test...

I forget the exact details, but basically a small propane/butane flame (maybe an inch or so tall) is held to every plastic component for something like 1-5 minutes--and when the flame is removed the plastic must self extinguish in 1 minute (or something like that).

This test was done because telephone central offices are very concern about fires and they know they cannot control by traceability every piece of plastic in a computer/switch/voice-mail system in a large commercial world. So this allowed some sort of assurance that there was not a time bomb waiting to go off.

They also did tests of the whole system by placing a 1/2 cup of alcohol in major sub-sections of the system and lit those off--how much smoke, fire, and how easy to put out with an extingusher was all checked (lighting off a $250,000-$1,000,000 proto type was crazy talk for us designers).

I have linked to this earlier panel fire thread often enough in recent history that you have probably already seen it...

But notice, the only reason the house is still standing is because asphalt shingles are relatively fire resistant (and a sharp eyed neighbor and nearby fire station) and the electrical short which started, and probably kept the fire going for a period of time, burned up a set of large plastic based (no glass) solar panel array (never would have been NRTL/UL approved or allowed to be installed on a home if the building inspector caught the error). There was probably 1-2 kWatts of heat available in the GT system to ignite those panels.

Please be real careful about this--Solar panels will feed a short (or arc an open if high voltage series string, or heavy current parallel string) very nicely. Larger systems with significant amounts of power (and a lot of plastic content and no metal containment) have all sorts of wonderful failure modes.

-Bill

Casting solar panels in composite material

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