DIY Solar Panel FAQ

 

4. hOW TO ENCAPSULATE SOLAR CELLS (EVA, TPT, Solar glass, sealant, other backing materials, ways to encapsulate the cells) etc.

Q4.1: Are these panels really 190 uM thick (0.19mm or .00019cm)? If so, what is the recommended mounting method for these paper thin fragile panels?

Q4.2: What is on the back side of solar cell? Is it 1/16" thick? Any clear coating over the photo surface?

Q4.3: What is the best type of glass to use for the panels? I'm sure I can find the angle aluminum frame material, and understand I will need to silicone well to make them completely water-proof. What are the materials most of your customers use without loosing the least watts?  

Q4.4: Case: This is my first DIY Panel, I expected only two tabs for soldering the connections. Do I need to put attachment wires on the other tabs to connect these cells like batteries in a flashlight top to bottom, and bottom to top, that would be a total of two wires on the individual cell, adding the voltages in series (right). Also do I need to epoxy the sun side of these cells to make them stronger and more robust? If yes, what do I use, do you have the epoxy, and do you have connection wire, and the silver solder?

Q4.5: What is EVA and TPT? I just figured to mount them between glass and plastic on plywood.

Q4.6: You have stated that protecting the cells from water moisture and air is important. You also talk about laminating. For a do-it yourselfer, how would you suggest this to be done? I was planning on enclosing everything in a custom water tight box, is that enough or should something more be done?

Q4.7: What type of Glass -- Acrylic, Plexi glass should be used to construct these? Can I use old sliding glass doors?

Q4.8: What kind of backing panel do you recommend for these to be mounted on? How many cells would you put on each panel? Where can you purchase the cover material for the finished panel?

Q4.9: Once the cells are soldered together in a panel and placed in a frame, should they be covered with glass? If so, should it be UV resistant?

Q4.10: Is there a difference between normal glass and solar glass? Could lexan, perspex be used in place of glass or would it affect the efficiency of the panel? Is there any guarantee on the solar cells, i.e. 5 year guarantee that they will operate at full efficiency?

Q4.11: Case: I got the output of my first panel up to acceptable limits. but the problem I'm having is condensation inside the panel. I'm sure when it first happened, it was because the panel wasn't tightly sealed. We experienced a hard rain and quite a bit of water got inside, ( enough to submerge the bottom row of cells. I removed the glass and let it dry in the sun for several days and i just can't seem to stop condensation from forming on the inside. I'm pretty sure i had it sealed up well this time around, but I'm out of ideas. I know that it's supposed to be air tight and to my knowledge it is now. But it seems that my mistake is leaving me with one option: to vent the panel. I was looking into using some fiberglass resin on it but I don't want to end up sealing water in with it. Do you got any ideas?

 

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Q4.1: Are these panels really 190 uM thick (0.19mm or .00019cm)? If so, what is the recommended mounting method for these paper thin fragile panels?

A. These solar cells (panels refer to the finished product after the solar cells are encapsulated in glass, EVA, TPT and aluminum frames are between 0.19mm and 0.26mm thick, after the coatings and metal contacts have been added to the base silicon wafers to make the solar cells. Today, all solar cells are made approximately in the same thickness. They are fragile, so you are absolutely right about that. However, even in this thickness they are still somewhat strong; you can handle them by hand when soldering the tabbing wires on them. They are easy to break, but most panels are made that way. Take a look at how to make solar panels video on YouTube and you will see that they will hold together in one piece if you are careful.

To protect the cells, you need to encapsulate them in a piece of glass, EVA, and a back sheet of TPT and put an aluminum frame around it. You drill wholes on the aluminum frame and you will then use mounting brackets to secure them on your structure.

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Q4.2: What is on the back side of solar cell? Is it 1/16" thick? Any clear coating over the photo surface? 

A: At the back of the solar cell, there is a layer of aluminum paste, but the layer is no where near 1/16" thick. The whole cell's thickness is not even that thick. It is only 0.2 mm in thickness. On the front, the shiny blue is silicon nitride, which is antireflective.

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Q4.3: What is the best type of glass to use for the panels? I'm sure I can find the angle aluminum frame material, and understand I will need to silicone well to make them completely water-proof. What are the materials most of your customers use without loosing the least watts?  

A: The best glass to use is the ultra white, low iron solar glass for panels. Solar glass is strong and can withstand the assault from hail. Honestly for home made panels it's hard to get to the efficiency that the professional manufacturers like Evergreen Solar can get, or else they would be out of business.

Regarding the 'panels' you mentioned. Let's use consistent terminologies here - we are selling solar cells in this listing, not panels. You string the cells together, encapsulate them and put frames and junction boxes around them, and they become 'panels'. Also, the cells we are selling are not the 'outdated' cells. Even those so called 'outdated' ones are still good. Remember I called them 'old style’; I didn't call them 'outdated'. Silicon based solar cells last a LONG time. You may change the number of finger lines on the surface of the cells etc, which is slightly different finger line screen printing, but once the cells work, they work for a long time, so I wouldn't reject them simply because they are 'old style'. A majority of the buyers were repeat customers who are more experienced and they recognize good materials. (I also notified them of the sale via email before the sale).

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Q4.4: Case: This is my first DIY Panel, I expected only two tabs for soldering the connections. Do I need to put attachment wires on the other tabs to connect these cells like batteries in a flashlight top to bottom, and bottom to top, that would be a total of two wires on the individual cell, adding the voltages in series (right). Also do I need to epoxy the sun side of these cells to make them stronger and more robust? If yes, what do I use, do you have the epoxy, and do you have connection wire, and the silver solder?
A:
First, something that's not obvious but very important: the front side of the solar cells (sunny side, with a lot of finger lines) is the negative terminal of the solar cells, namely, both the white bus bars across the solar cells are negative. The back sides of the solar cells are positive, and there are 6 soldering points that are all positive. You solder the tabbing wires on the front of the cell completely, and then that same tabbing wires should be soldered to the next cells' back side on the same side, using all three on the same side, that is. It would be very helpful to watch free videos on YouTube to get a visual on how cells are put together.

You will definitely need to protect the solar cells with encapsulants. The standard encapsulant is EVA sandwiching the solar cells, TPT at the back, and solar glass on the front. But these work best if you have access to a laminator to melt the EVA and vacuum the air bubble out of these layers of protection. Home made DIY manuals suggest other methods that are more easily achievable at home. The key is you need to make sure that these fragile solar cells are protected against impact, and moisture.

We have been trying to focus on selling the largest number of cells and we say we are not educators, so we are working on identifying the best DIY panel teachers out there and will partner with them.

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Q4.5: What is EVA and TPT? I just figured to mount them between glass and plastic on plywood. 
 A:
EVA stands for Ethylene-Vinyl Acetate, it's a copolymer that melts easily and has strong adhesive properties that make it bond with glass and the TPT (Tedlar-Polyester-Tedlar) backsheet. They provide excellent protection against water, moisture and air. But since to use these materials you need to have access to an industrial laminator and it may not be practical. Some people use a heat gun and shop vacuum to improvise this. Your glass / cells / plastic / plywood might work but it won't last long as what the pros produce. But you have to work with what you have and what's practical.

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Q4.6: You have stated that protecting the cells from water moisture and air is important. You also talk about laminating. For a do-it yourself, how would you suggest this to be done? I was planning on enclosing everything in a custom water tight box, is that enough or should something more be done?

A: Your method could very well work for a few years, maybe even 10 if you do a real good job making it water tight, but there is no guarantee. There are a lot of techniques and details steps in making a professional solar panel and all those little things make a big difference over the long run. But even over the short run you might have already gotten your money's worth out of it with your current solution. Let me tell you the EVA solution.

EVA is the more ideal encapsulant. All pros use it. Get two layers of EVA the size of your panel. Sandwich your cells in between these two layers of EVA. Than at the back of the EVA, put a layer of TPT. The on the front of the EVA and cells, put solar glass. Now you have 5 layers. Pros use an industrial laminator that most people don't have access to. For DIY folks, you can use a heat gun blowing at the 5-layer laminate, and let the heat gun melt the EVA, which seals the cells. At the same time you heat the EVA, you need to use a shop vacuum to extract the air out of the laminate, so that your final laminate does not have air bubbles. As you use the heat gun to heat the EVA, use a roller to press the laminate like the way you would paint a floor, with a rolling action following the heat gun.

The objective is to make sure that that your cells are protected from water, moisture, and impact.

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Q4.7: What type of Glass -- Acrylic, Plexi glass should be used to construct these? Can I use old sliding glass doors?

A: Ideally you will want to use solar glass, which has three properties:

1) It has surface treatment to reduce sun light reflection when it hits the surface of the glass
2) It is ultra white in the sense that it has very low iron content in the glass. This increases the absorption rate of sun light that doesn't get reflected
3) It is tempered so that it becomes strong enough to withstand the assault from hail, flying little rocks etc. And it also won't shatter.

The question is where to get them. It's not easy, and we are not carrying them at the moment. They usually need to order directly from the solar glass manufacturer because they can not be cut once it's tempered. Solar glass manufacturers don't take orders from individuals like DIY folks though. We are thinking of getting them because we have the scale but we are not there yet.

Therefore you might have to live with the glass that you can get from your local hardware store. Prepare to lose 12 to 13% of the power of your solar cell because of not using solar glass. If you have access to the people who build green houses with glass, perhaps that's a better choice than sliding glass door glass.

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Q4.8: What kind of backing panel do you recommend for these to be mounted on? How many cells would you put on each panel? Where can you purchase the cover material for the finished panel?

A: We suggest that you encapsulate the solar cells between two layers of EVA, then TPT backing. On the front side, use solar glass. That's the most ideal, but these materials are hard to find.  You can sandwich the solar cells in two layers of glass and seal the edge of the glass with silicone and that's a slightly compromised solar panel. Not ideal, but you have to do what's practical sometimes. And even if you can get the most ideal backing material, laminating them requires a big industrial size machine.

I would recommend you to start up with building panels containing 36 cells, with 4 columns of cells, and 9 rows. After you became more comfortable with building up a 36 cells solar panel, then increase to 72 cells. And don't go too much beyond that. Going beyond that, things get more complicated than what a beginner is ready to tackle.

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Q4.9: Once the cells are soldered together in a panel and placed in a frame, should they be covered with glass? If so, should it be UV resistant?

A: Yes it should be covered with glass, and ideally you should use solar glass that's UV resistant, ultra low in iron to increase sun light absorption, and treated with anti-reflection layer and tempered to make the glass strong. In the absence of solar glass, use substitutes such as green house glass, plexiglas or polycarbonate. They are not ideal, but you need to protect the cells.

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Q4.10: Is there a difference between normal glass and solar glass? Could lexan, perspex be used in place of glass or would it affect the efficiency of the panel? Is there any guarantee on the solar cells, i.e. 5 year guarantee that they will operate at full efficiency?

A: Yes, compared to regular glass, solar glass has three properties or advantages that make them most suitable for solar panels. First, solar glass has anti-reflective treatment which reduces sun light reflection. Second, the materials used to make the glass is low iron and ultra white, it reduce less light reflection and allows more to pass through the glass. Third, it's tempered, making it very strong and hard against the assault from hail and other hostile objects. 

Anything other than the solar glass will have an efficiency drop. Even solar glass is not perfect. It's just comparatively the best materials to use. 

No, there are no guarantees on the solar cells. At these extreme low prices, we cannot offer guarantees. But thousands of customers have not hesitated to buy from us before you. And they are happy with the deals they got. 

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Q4.11: Case: I got the output of my first panel up to acceptable limits. but the problem i'm having is condensation inside the panel. I'm sure when it first happened, it was becasue the panel wasn't tightly sealed. We experienced a hard rain and quite a bit of water got inside,( enough to submerge the bottom row of cells. I removed the glass and let it dry in the sun for serveral days and i just can't seem to stop condesation from forming on the inside. I'm pretty sure i had it sealed up well this time around, but i'm out of ideas. I know that it's supposed to be air tight and to my knowledge it is now. But it seems that my mistake is leaving me with one option: to vent the panel. I was looking into using some fiberglass resin on it but i don't want to end up sealing water in with it. Do you got any ideas? 

A: The solar panels have to be 100% water tight in the first place. The only way to make to do it is to use the professional encapsulation methods, which involve using EVA, TPT and a laminator. If you use home made method to seal the solar panels that might work too. In that case, people use a heat gun to blow hot air on to the glass, and at the same time you use a roller to roll on the glass to squeeze out the air as much as you can. The other method is to use epoxy to pour onto the surface of the solar cells so that moisture does not get into the the solar cells.

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