Air vent for solar panel

[scheek]

This is my last question before I get one answer to the others.

I am sandwiching my cells between glass panels. I've seen on several diy panels the builder says to leave air vents in the bottom to prevent fogging. On another,(which I really like and copied) shows using silicone between the sandwich glass panels. He has made his air tight.

Before enclosing, which method should I use?

[Mike90250]

it will die from moisture intrusion either way. To get silicone goo inbetween the glass, and not crack the cells, as you vacuum the air out, is VERY tricky. Maybe he used 2 part pourable $$ silicone. Silicone is not water vapor proof.

[scheek]

So you don't have a suggestion?

[Mike90250]

I've not tried to build one, so I can't say what works. I think a vent at the bottom will be the easiest. Maybe use a soda straw, to keep a small hole open, and seal the rest? I don't know.

[SunnyLight]

Sillicone is water proof

Personally I build three panels sofar using the sillicone construction, closing the panels completely. It is not necessary to create a vacuum, all you have to do is add silica gel which absorbs the water what is in the air upon closing it. Sillicone is very water tight and proven to work for long time. Take a look at how insulated glazing is made. Basically I use the same method, just I dont use the spacer of aluminium. But that is not necessary, just convenient and cheaper for factory production (but we're doing diy). See wiki about double glazing.

http://en.wikipedia.org/wiki/Insulated_glazing

I used sillicone which is used in the glass industry and costs around $5 a panel. This is not expcensive considering the rest of the costs.

DO NOT and I repeat, do not leave the panel open. If you create a hole then you will be sure that on wet days your cells will degrade quickly and your panel wont last very long.

Hante

[philpaine]

Impact of Moisture on Cells

Please can someone give a bit more info on the impact of getting moisture within diy solar panels?

To what extent does it degrade performance?
Why does it reduce cell life?

Many thanks for your help.

Thanks

Phil

[SunnyLight]

Solar cell protection

This is from a website where I got much of my info from:

The key purpose of encapsulating a set of electrically connected solar cells is to protect them and their interconnecting wires from the typically harsh environment in which they are used. For example, solar cells, since they are relatively thin, are prone to mechanical damage unless protected. In addition, the metal grid on the top surface of the solar cell and the wires interconnecting the individual solar cells may be corroded by water or water vapour.

And here is a link to the website:

http://pvcdrom.pveducation.org/index.html

Chapter 7.1 Module constuction.

Basically you have to worry about corrosion, just like with most electical equipement.


Hante

[Mike90250]

Water IS the universal solvent, and it works very fast in the presence of electricity.

That's why a flash drive works after washing & drying, it's just metals. When you add electricity (like sun shining on a solar panel, or a cell phone with a battery in it) current starts to flow between the metals, and migration and corrosion starts happening, at some point, the part dies.

[philpaine]

Dealing with Moisture within Solar Panels

Thanks for the replies chaps.

Some more queries:

If I was to make a solar panel, using say, a 1/2inch ply backpanel, 1/4inch Plexigalss front panel sandwiching a 1 x 1/4 in frame. If I seal everything using clear silicone and include bag of silica gel (as suggested by another member of this forum), wouldn't that deal effectively with the issue of moisture?

Any thoughts?

Thanks again

Phil

[Mike90250]

nice try. Won't last too long - a year or so. Water vapor will shoot right through painted 1/2" plywood. Maybe if you got some sort of epoxy, it would be better, but even epoxies are a sieve to water vapor.
But no one believes me, so build away.

[philpaine]

Hi Mike

I am happy to believe you!

What about the use of silica gel - won't that absorb the excess moisture (can always have "lots" of silica gel if that would help?

Phil

[Mike90250]

Hi Mike

I am happy to believe you!

What about the use of silica gel - won't that absorb the excess moisture (can always have "lots" of silica gel if that would help?

Phil

You'd have to be changing it all the time. Water vapor is nasty stuff, slows down a bit for plastic & epoxy, but is very hard to seal out.

[philpaine]

Hi Mike

OK, so what are the pratical options?

What can you do to make a solar panel and give it longevity?

Phil

[Mike90250]

Hi Mike

OK, so what are the pratical options?

What can you do to make a solar panel and give it longevity?

Phil

You can't, that I know of, at home, without some exotic machines. But you can assemble one, learn from it, wire in series, wire in parallel, and have a fun science project, but for a trouble free +20 year lifetime, not likely.

[philpaine]

Lets assume ...
OK, so I make my solar panel, take my time to ensure the tab wires, etc, are properly soldered, no dry joints. I make a good job of sealing it and as a bonus I seal in half a dozen bags of silica gel.

My 60w solar panel dilivers 18+v and 60 watts in direct sunlight on a bright sunny summer day.

Working with the above assumptions, when would I expect to see a noticeable degradation in performance. 5, 10, 15 or 20 years?

Can you eleaborate?

Thanks

Phil

https://www.solar-panel-home.net