DIY solar panel

CBlack

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May 14, 2018
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Hello!

Hopefully a simple one. I am wanting to make a 48v system but do not have the budget for a good build to do it so far. So i am going to build a modular style 12v that can be rewired later into a 48v system. I have about 1k worth of cells that need to be tabbed and connected.
Looking for a little guidance/suggestions on the best way to make the 12v system so that it can be changed from a parallel system to series system when i get the budget later down the line. they are standard cells that are 3x6. I have about 530 to 560 cells total.

If i am leaving something out, let me know and I will update with that information.

CB
 
Lithium Cobalt can not effectively/properly be configured for a 12V setup. The reason being you get either 3s or 4s, which both are not suitable.

However, a 24V system is. It is generally wired up as 7s. Which, to make 48V, you just double them together to get 14s.
Which, 14 cannot be equally divided by 3 or 4. So this is another reason to not go this route, unless you want to completely rewire your setup.

And to add, if you don't have a large enough budget to make a 48V system now, you won't have a good budget to convert over later. The reason being, you will need to use much heavier wire for the 12V/24V over the 48V. The inverters for 12V/24V are not that much cheaper than 48V, and they cannot be used with 48V, meaning you have to re-invest in inverters.
The same goes for the chargers.

In the end, you will have spent at least twice as much than if you just waited a bit longer to build the 48V system. This is one reason why I have not built my powerwall yet as I have not been able to buy the 48V equipment yet.

And buying cheaper equipment with the mindset of selling it later to recoup the losses, is not gonna work. A used inverter goes for about 3/4 of a new one.



hahah, just noticed, you say 530 to 560 cells, and I was thinking battery cells, not solar cells :p doh! The above is still valid, though

for 12V "solar", I agree with Jason below. There's also several videos that show the process of making the panels. Have you watched those? I'll look for some of the ones I have seen and post them later.
 
Be very carefull with the solar cells. They are easy to break and become brittle from heating/soldering them
 
Each cell will be around 0.5V so you can wire 24s sets and then combine these into parallel / series sets to scale up to 48V. Depends on the cell specifications (Vmp / Voc/ Amp) and what you are mounting the cells on / covering them with - size of the board / glass.
 
I know DIY solar panels sounds like a great project, but unless you got those cells for free it's easier (and probably cheaper in the long run) to buy used panels. You can get a used panel for around $50USD if you look hard enough. It's properly sealed so will last the 20 years that it's rated for. This probably hard to achieve with a DIY panel.

Most residential panels are made with 6x6 cells and in a 60 cell configuration. This will give anywhere from 200 to 300watts of power. The average voltage is 30Voc.
Some commercial panels are made with 6x6 cells and in a 72 cell configuration.

There's no 48V panel. Instead the solar charge controller handles the charging aspects. For example some MPPT charge controllers handle 500VDC. So all those panels will be linked in series until they reach 500VDC. Then it will buck the voltage to charge a 48V battery bank, or a 24V battery bank, etc.
 
CBlack said:
Hello!.....they are standard cells that are 3x6. I have about 530 to 560 cells total.....

Your post is not too clear CBlack .... you mean you have 550 of these ... these are 3x6 cells .....

s-l225.jpg


If so , I don't quite think yourealise what you are getting into !!!

I spent a long time playing with these , building my own panels ... not to save money , I very soon realised to make your own panels is more expensive than buying them ready made ... I did it for the education and experience .....

You have to first solder them together using tab wire , a tricky and skilled job .... then they have to be Encapsulated ...

Two ways of doing this , either buy liquid resin encapsulator ....ridiculously expensive .... or bond them to glass , you need a vacuum heater machine, to melt the sheet of plastic used for bonding .... not realistic .... I did build my own heater machinewhich had limited success...

Unless you encapsulate these cells , they will deteriorate very rapidly ..

You say you already have these cells.... !!! I would cut your losses and not pursue this (unless you're looking to get an education by experience)... it is a black hole of unending expense , at the end you will have some dodgy looking panels that cost twice what new ones cost...

Look for second hand panels they are underpriced everywhere ... remember even after 25years use , panels still output 80%of the power they did when new ... after 50 years probably more than 50%...
 
ozz93666 said:
CBlack said:
Hello!.....they are standard cells that are 3x6. I have about 530 to 560 cells total.....

Your post is not too clear CBlack .... you mean you have 550 of these ... these are 3x6 cells .....

s-l225.jpg


If so , I don't quite think yourealise what you are getting into !!!

I spent a long time playing with these , building my own panels ... not to save money , I very soon realised to make your own panels is more expensive than buying them ready made ... I did it for the education and experience .....

You have to first solder them together using tab wire , a tricky and skilled job .... then they have to be Encapsulated ...

Two ways of doing this , either buy liquid resin encapsulator ....ridiculously expensive .... or bond them to glass , you need a vacuum heater machine, to melt the sheet of plastic used for bonding .... not realistic .... I did build my own heater machinewhich had limited success...

Unless you encapsulate these cells , they will deteriorate very rapidly ..

You say you already have these cells.... !!! I would cut your losses and not pursue this (unless you're looking to get an education by experience)... it is a black hole of unending expense , at the end you will have some dodgy looking panels that cost twice what new ones cost...

Look for second hand panels they are underpriced everywhere ... remember even after 25years use , panels still output 80%of the power they did when new ... after 50 years probably more than 50%...

Yes, 550 ish of the solar cells. Part learning and part testing waters. I got them really cheap and was testing how well I can do. 1kwh for 99.
 
I thought about making my own as well. I've held off on it as I wanted to do a lot more research. I have several (and can get more) tempered glass I got for free. They were sliding glass doors that weren't being used anymore. About the right size for solar panels. Just have to replace the frames with something better/lighter.

But, as ozz says, the encapsulation is not cheap. Either the vacuum/heat method or the UV resistance stuff you mix together. I don't mind if it takes me time. That I have plenty of and would rather spend it working on something productive than squatting on my chair. So that doesn't bother me. But the added costs associated would definitely need to be calculated in to make sure it's worth it.
 
Korishan said:
I thought about making my own as well. I've held off on it as I wanted to do a lot more research. I have several (and can get more) tempered glass I got for free. They were sliding glass doors that weren't being used anymore. About the right size for solar panels. Just have to replace the frames with something better/lighter.

But, as ozz says, the encapsulation is not cheap. Either the vacuum/heat method or the UV resistance stuff you mix together. I don't mind if it takes me time. That I have plenty of and would rather spend it working on something productive than squatting on my chair. So that doesn't bother me. But the added costs associated would definitely need to be calculated in to make sure it's worth it.

i was just looking at the eva film and it is not bad. that door idea is pretty damn awesome! I will look for used one on local face book. it should have the metal frame around it and will not flex. at the point, i am just looking to get it up and working on the back porch so i can get my local training in. I am a firm believer that i will not do it right on the first try and will take at least one iteration. Also the eva film overlaps and bonds to gather really well. So i can take my cells and make the best combo after i find a door.

thanks guys! (gals if there are any that helped.)
 
Yeah, the doors are great because they have to be tempered by code. So all sliding glass doors are fully tempered. I've gotten all mine off Craigslist in the Free section ;)
We also have a local recycler of random construction stuff (people donate left over construction or ripped out parts that were replaced in a remodel) and those doors go for $20 each. Pretty good bargain considering you can't even get the hardware for that price new.
Also, usually glass doors are very smooth on both sides. If you get full sized windows, they may have bows/ripples in them and it's ok for a window. But for doors it's not. So it's better quality glass overall.

Yes, first iteration is the main learning curve and except that there will be mistakes during the process. But, at the same token, you do your darnedest to not mess it up :p
 
Korishan said:
Yeah, the doors are great because they have to be tempered by code. So all sliding glass doors are fully tempered. I've gotten all mine off Craigslist in the Free section ;)
We also have a local recycler of random construction stuff (people donate left over construction or ripped out parts that were replaced in a remodel) and those doors go for $20 each. Pretty good bargain considering you can't even get the hardware for that price new.
Also, usually glass doors are very smooth on both sides. If you get full sized windows, they may have bows/ripples in them and it's ok for a window. But for doors it's not. So it's better quality glass overall.

Yes, first iteration is the main learning curve and except that there will be mistakes during the process. But, at the same token, you do your darnedest to not mess it up :p

So i grabbed some number from ebay for a few different sizes..


image_krukfj.jpg


I have attached a screen shot of the math break down. they are listed in MM on first column and Inches on second, both are the same.

So the door would take care of the frame and give a great flat surface and pretty large area to work with. So i could make more than one 24 v panel on it to go back later on to wire into a 48v system or just get my cheap 48v from china from the start.

What is your thoughts on grid tie vs used a straight invertor with an auto switch setup?

CB
 
CBlack said:
So i grabbed some pricesfrom ebay for a few different sizes.. (of eva)
Fantastic ....

This is what eva looks like ...

s-l225.jpg


It's a plastic sheet that goes between the cells and the glass ...

After you bought that you need one of these ....

solar-panel-laminator-250x250.jpg


Only $50,000 .... this evenly heats the glass sheet and cells so the eva melts and bonds everything , also applies a vacuum veryimportant to prevent air bubbles

Don't have $50,000??? ....you can try using a hot air gun .... most of the time you will crack the glass ... but it is possible if you keep the size of the panel down to about 20cm x20cm... but you will have air bubbles trapped and it will look a mess .

You also need a white plastic backing sheetto protect the backside of the cells , and pva sheetto glue that on ...
 
What about using 2 sliding door windows - one for the back and the other for the front ?

Is the vacuum just to prevent oxidisation of the cell surface ? If the two windows are sealed around the edge and then filled with Argon (cheap welding gas small bottle or a friend with a welder...) would that not do the same job ?

Just throwing some unconventional ideas around.... :D
 
If you do the glass with the film, making a heating box is relatively easy. Just have a firebox off to the side, and then make a large container box to hold the hot air in and let it raise up to the glass. That'll make the glass evenly heated. That's not much of an issue.
The bigger issue is making sure all the air is vacuumed out from around the cells. And yes, completelycharged, it's to help keep from oxidation. I suppose you could build another box on top of the panel and use a A/C pump to pull the air out of the chamber. But that would need to make sure that it is precisely sealed all around the perimeter.

It's not overly as complicated as ozz is making it out to be. It just takes a bit of ingenuity and lots of research before you actually start. We all have to start somewhere.
 
so i need eva on both front and back sides? not buying a big ass machine, (i like the use of sarcasm) so i will take my happy ass over to HF and get a hot air maker. The backing will be a super soaked small plywood that has been treated. The goal is not to make a 100% sell-able project but one that i can put on my back porch to get some free sun to project. I have a pad that is 15 by 23 feet that is not being used for anything but holding the ground down.

CB


Korishan said:
If you do the glass with the film, making a heating box is relatively easy. Just have a firebox off to the side, and then make a large container box to hold the hot air in and let it raise up to the glass. That'll make the glass evenly heated. That's not much of an issue.
The bigger issue is making sure all the air is vacuumed out from around the cells. And yes, completelycharged, it's to help keep from oxidation. I suppose you could build another box on top of the panel and use a A/C pump to pull the air out of the chamber. But that would need to make sure that it is precisely sealed all around the perimeter.

It's not overly as complicated as ozz is making it out to be. It just takes a bit of ingenuity and lots of research before you actually start. We all have to start somewhere.

I know HF make a pretty bad ass suction pump that i have seen used to hold down materials for CNC and would fit the bill for that and would not cost an arm and a leg. besides the large ass vacuums that i currently own.
 
Get an old fridge that is being thrown away and take the compressor off, use it as a vacuume pump... might be slow but they are good.
 
That's a big undertaking for anything other than a learning / because you can experience.

From a time / effort standpoint I don't think its worth making panels unless you need to do so for a special application like those solar wing gliders where you cant just get something off the shelf. I very much agree with the used panel route if you need to save coin.

On top of that you have testing, warranty, output characteristics, and if you ever want to upgrade, resale.
 
CrimpDaddy said:
That's a big undertaking for anything other than a learning / because you can experience.

From a time / effort standpoint I don't think its worth making panels unless you need to do so for a special application like those solar wing gliders where you cant just get something off the shelf. I very much agree with the used panel route if you need to save coin.

On top of that you have testing, warranty, output characteristics, and if you ever want to upgrade, resale.

in my area, the used ones are not cheap and shipping for new ones are insane. Also i like making stuff.
 
completelycharged said:
Is the vacuum just to prevent oxidisation of the cell surface ? If the two windows are sealed around the edge and then filled with Argon (cheap welding gas small bottle or a friend with a welder...) would that not do the same job ?

Just throwing some unconventional ideas around.... :D

In the professional machine the prepared panel is put inside ... this is glass / eva /cells /eva / white backing plastic ...

It is put inside a heavy duty plastic bag inside the machine , .... the air is suced out of the bag to make the vacuum , so atmospheric pressure is pushing the glass and the white backing sheet together attremendous pressure10 tonnes per square meter of panel !! ...

so the vacuum is to make sure no air bubbles in the top layer of eva , they will scatter light away from the cell , and look unsightly ... but also the vacuum pushes the whole sandwich together , making sure the now hot liquid eva gets into every crevice.

This is not easy for the DIYer to replicate without considerable investment , vacuum pump , heating chamber , ..

I built a heating element composed of a lattice of wire sandwiched between two glass sheets , epoxy fixing theglass sheets together . Passing current through the wire heats it up evenly , pressed hard onto the panel it melts the eva and does the job ...sort of ... some air bubbles ...

If trying to use eva , I would advise not to make the panels too large ...very difficult ...

Remember even if all goes well , it's still cheaper to buy the panelsfrom the manufacturer ..

In CBlacks case , where he already has bought the cells , unless very technically minded with a good workshop, liquid encapsulant might be a better choice.

The trouble with the idea above from compleatlycharged ofjust sealing between two glass plates with silicon , is that as the panel gets hot in the sun the argon will expand , build up pressureand find a way out , then cooling will suck in moist air .... I think it's humidity which destroys cells ...

I would advise CBlack first to try soldering the buggers (6x3s) together !!...this puts of most DIYers before even getting to encapsulation!!


CBlack said:
.... The backing will be a super soaked small plywood that has been treated.

I'm not sure the eva will bond well with plywood , also essential the backing is not permeable to any extent ...

I used glass as a backing on mostpanels I made , so that's glass/eva /cell/eva/glass ... you can normallyget glass free from your glass shop , they scrap glass 400mm wide ... for the front glass try to get low iron glass , it lets more light through , most glass shops stockit ...

My advice is keep the panel size very small, it's much better to have a small suckcess than try to make a big panel and lose many cells in a disaster ....

Good Luck ... you will get an education doing this!
 
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