Need opinions on a small solar setup

[JR]

Hello folks!

First post here and firstly I apologize if I'm being dumb here but I need some advice. I live in Finland and have a summer cottage (never go there at winter time), which isn't anywhere near to power lines, so I've come to think about solar energy. I'm planning to hook up a small (low budget) solar system and here's my plan so far:

DIY panels (figured it would come much cheaper that way, PLUS I'd really enjoy actually doing something to make it work). I'm thinking of buying either 72 or 108 solar cells (~1.6-1.8W each) to make 2-3 ~60W panels in parallel to load some 12v battery. I've been searching from ebay and found sets like this: http://cgi.ebay.com/72-grade-solar-panel-cells-3X6-1-75W-each-TESTED-/180513660983?pt=LH_DefaultDomain_0&hash=item2a0773e037#ht_3603wt_1035 . The prizes seem reasonable to me, what do you think?

Should the frame be made out of aluminium or will plywood or something else do the job? And if 72 cells are rated total of 126 watts (72*1.75W), what kind of power can I realistically expect to see going to my battery bank after charge controller?

We'll be living approximately 2 days a week in the cottage at summertime and so far we've survived nicely without any electricity at all so any improvement is a big improvement. I'd like to be able to use a laptop and TV occasionally (2-3h/day), load cell phones, put on a few energy saving lamps at nights and perhaps power a small fridge as well. So I'll hook up my battery bank to a 230Vac inverter (which will waste efficiency 10 to 15%, right?).

The battery "bank" will only be around 100ah at first (until I can afford more). I'm not sure if it's big enough capacity for my needs if it's cloudy for 2 days straight and whether or not my panels will produce too much power that goes wasted when there's sun and no need for electricity. Any opinions much appreciated!

And lastly, I really want to accomplish this so if there's any general advices, typical rookie mistakes to avoid or important things to remember, I'm all ears!

Thanks!

[Volvo farmer]

DIY panels (figured it would come much cheaper that way, PLUS I'd really enjoy actually doing something to make it work). I'm thinking of buying either 72 or 108 solar cells (~1.6-1.8W each) to make 2-3 ~60W panels in parallel to load some 12v battery. I've been searching from ebay and found sets like this: http://cgi.ebay.com/72-grade-solar-panel-cells-3X6-1-75W-each-TESTED-/180513660983?pt=LH_DefaultDomain_0&hash=item2a0773e037#ht_3603wt_1035 . The prizes seem reasonable to me, what do you think?

Should the frame be made out of aluminium or will plywood or something else do the job? And if 72 cells are rated total of 126 watts (72*1.75W), what kind of power can I realistically expect to see going to my battery bank after charge controller?

I built panels out of those same Evergreen cells, but they were seconds, not "A" grade. I can tell you that I get about 2.5A @24V or about 60 watts out of 72 of those cells at solar noon. 

You are going to have to buy tabbing wire and bus wire for those panels, plus you will need to cover them with glass and attempt to seal out the elements. My panels get moisture in them every time it rains, and I had them sealed professionally at a glass shop. I would be extremely surprised if you could build a 72-cell panel for less than $200 in materials.

Right here is a 135 watt factory panel, with a 20 year warranty for $353
http://www.altestore.com/store/Solar-Panels/100-to-149-Watts-Solar-Panels/Kyocera-KD135GX-LFBS-135W-12V-Module-Blue-Cells/p8471/

If you really want to power some things with solar electricity, you should buy pre-built panels. If you really like soldering, assembling, gluing, and sealing and don't mind if your panels don't last as long as factory panels, I suppose you could build your own, but trust me, you will have many hours of effort into building your own, and in the end you will have an inferior product without much real savings.

[Bruce S]

JR;
 Welcome to the board.
I took a look at the specs of the individual cells.
Firstly they do look nice. BUT ---You knew this was coming right---
they specs show that they are only 0.5Vdc ea and you will need 2 to make ~1.0Vdc so you are going to need at least 24 to make 12Vdc
IT gets deeper. Since you are looking to use a 12V battery you will need to get above 12V to get the panels to charge the battery.
Most batteries when fully charged actually reach 13.4V some even higher. This is one of the reason way you will see pre-made panels that have 36 cells.

This still only get you the original 1.75 watts of input, since the 24+ cells will need to be assembled in series to get the voltage up there. If you go with the standard 36 cell configuration then you will have a better chance of getting charged battery(ies).
By getting all 108 then you could end up with about 60+ watts of power in total, doing mental math here so forgive if numbers are slightly off .
100Ahr battery bank sounds good, BUT to be sure you don't drain the battery so much that it hurts the battery's ability to recharge you will need to add  up all the power ALL the devices that could be used.

ALSO how handy are you with soldering? and such? this is not usually for the beginner. Finland has PV plants, you should be able to find pre-made panels for a fair price and think of the time you'll save.

Don't want to scare you away from doing this, others already have. You might want to search our board and read up on their experiences too.
Cheers
Bruce S

 
 

[zander1976]

Hey,

I am working on building a panel right now, my first one. I would say that soldering the first cell was a pain. I used a 30watt soldering iron and it was horrible but after about 4 hours I had all 40 or so of them done and was pairing them. The first one was hard, I would say it took as long as the last 10. It gets much easier and with some good music on its a great way to pass the time.

There is a product called SYLGARD 184 that you can use to cover the solar cells. It will make your life a lot easier if you are trying to figure out how to protect the cells ones you have them all together. Markp-0177 has a good video on how to make them: http://cgi.ebay.com/Solar-Panel-Frame-glass-36-3-x6-tabbed-cells-/180500968062?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item2a06b2327e#ht_500wt_1154

Goodluck.

[Volvo farmer]

There is a product called SYLGARD 184 that you can use to cover the solar cells. It will make your life a lot easier if you are trying to figure out how to protect the cells ones you have them all together.

Yo Zander. Have you actually purchased some of that sylgard stuff and used it on your solar panel?

[JR]

Thanks for all the input!

I built panels out of those same Evergreen cells, but they were seconds, not "A" grade. I can tell you that I get about 2.5A @24V or about 60 watts out of 72 of those cells at solar noon.  

You are going to have to buy tabbing wire and bus wire for those panels, plus you will need to cover them with glass and attempt to seal out the elements. My panels get moisture in them every time it rains, and I had them sealed professionally at a glass shop. I would be extremely surprised if you could build a 72-cell panel for less than $200 in materials.

Right here is a 135 watt factory panel, with a 20 year warranty for $353
http://www.altestore.com/store/Solar-Panels/100-to-149-Watts-Solar-Panels/Kyocera-KD135GX-LFBS-135W-12V-Module-Blue-Cells/p8471/

If you really want to power some things with solar electricity, you should buy pre-built panels. If you really like soldering, assembling, gluing, and sealing and don't mind if your panels don't last as long as factory panels, I suppose you could build your own, but trust me, you will have many hours of effort into building your own, and in the end you will have an inferior product without much real savings.

I looked at the panel in your link and ieven though I agree it's cheap, it says they don't ship to Europe. In finland they sell 130W solar panels in a range of 450€-600€! So that's like $600-$800. And yeah, I really like the DIY aspect as well and not just plug a couple cables in and sit down and relax. I don't know if it makes any sense

About the moisture, is it critical and how do you get it away once you notice it? Is there a noticable loss in power and does it hurt the cells or what?

So am I getting this right? First I need an aluminium plate (any cheaper materials I could use instead?) and mount my cells connected in series on it with some glue or silicone that can stand the heat. Just glue the center of the cells to avoid cracking them when the panel "lives". Then I'll need to mount a glass panel on top of the frame and make sure everything is sealed well. Of course I need to drill two holes in the back for positive and negative leads. Is that about it? Also, I will look into that SYLGARD 184 stuff, thanks for the heads up, zander!

Bruce, I understand I need 36 cells to make a sufficient panel for a 12v system, and that's why I was thinking of either buying 72 or 108 of them (to make 2 or 3 panels and connect them in parallel). "This still only get you the original 1.75 watts of input, since the 24+ cells will need to be assembled in series to get the voltage up there." This is something I don't quite understand. Isn't the wattage supposed to be multiplied as well when the voltage goes up? So if one cell is rated 0.5V and 3.4A, then 36 cells should be about 18V*3,4A=61W. I'll definately search the forums for more experiences. It looks like you guys have a great informative community here!

[Volvo farmer]

If you look at this thread and scroll down, I have posted three links to my solar panel project.  I glued the cells to a piece of glass with a single dab of  "primerless window glazing adhesive". I then had a glass shop sandwich another piece of glass on top and seal it up as you would a double pane window. 

http://fieldlines.com/board/index.php/topic,135682.0.html

These panels have been making power for exactly four years now, and I am unaware of any person who has ever posted on this board who has been making power with DIY panels for this amount of time.  I put in small vents to let the moisture escape and so far, it has not hurt anything yet.

I have heard of people buying laminators, and pouring all sorts of clear goopy stuff over cells like that sylgard, but I have never seen them post in this forum with their results, nor have I seen anyone post back after their panels have been out in the weather for a few years.

Good luck with your project. I really hope you like tedious, repetitive work, because there are 432 solder connections in each 72 cell panel. 

[JR]

Thanks for the link Volvo Farmer. I'll take a deeper look at it in a couple days, cause now I'm in a hurry to make my last visit to my summer cottage this year.. Can't surf the internet there (remember, no electricity AT ALL atm ). This thread has made me rethink the whole DIY thing. I'd hate to see my hard work go wasted after a year or so use. We'll see and I'll keep you guys updated if I get anything done! And no, I'm not giving up yet, just re-evaluating whether to buy the panels or make my own.

[zander1976]

There is a product called SYLGARD 184 that you can use to cover the solar cells. It will make your life a lot easier if you are trying to figure out how to protect the cells ones you have them all together.

Yo Zander. Have you actually purchased some of that sylgard stuff and used it on your solar panel?

Not yet, I am going to order some when I get my next paycheck and give it a go. Seems way easier then trying to seal/vent cabinets and all the problems that come from that.

[zander1976]

Hey volvo,

Yeah I remember reading your post on it a while back. When I ran into the sylgard it kind of reminded me of it. The basic use of it is put your cells face down on glass and then poor the sylguard over the back of them to glue them in place. If you wanted you could put another sheet of glass across the back similar to what you mentioned for added strength. Thats about it, the only reason I was thinking of using it is that it doesn't block light and seals the thing.

Zander

[Volvo farmer]

Not yet, I am going to order some when I get my next paycheck and give it a go. Seems way easier then trying to seal/vent cabinets and all the problems that come from that.

Well then, let me ask you a question. How would you feel if you recommended the stuff, like you did to that JR fellow, then after you tried it on your solar panel, you found it to be a horrible failure?

Just sayin, Maybe you should try and be really clear when you recommend a product to solve a problem, that you have either tried it or not. The way you were throwing it around as a solution sounded like you had actual experience with the product.

[zander1976]

Not yet, I am going to order some when I get my next paycheck and give it a go. Seems way easier then trying to seal/vent cabinets and all the problems that come from that.

Well then, let me ask you a question. How would you feel if you recommended the stuff, like you did to that JR fellow, then after you tried it on your solar panel, you found it to be a horrible failure?

Just sayin, Maybe you should try and be really clear when you recommend a product to solve a problem, that you have either tried it or not. The way you were throwing it around as a solution sounded like you had actual experience with the product.

Well, I think my point was the video more so then the product. The video covers everything from tab wire, bus wire, diodes to what he uses to seal them. Its not like its difficult to see how it would be significantly easier then the million other posts regarding building sealed or vented frames and its not like I didn't research it first. Its a 50 dollar product that seals and doesn't block light. Its not like I recommended putting nano pilars on the solar cell that required a research department. I get your point, relax a bit. In the end I would still recommend it over trying to build a sealed cell using whatever or the many other attempts that may or may not work and at a cost of 50 dollars I would say even if it didn't work for more then a year there are many more options that won't last a year that will cost a lot more. So yes I can say with confidence that its not going to be worse then the million other options that have been tried and didn't work.

[zander1976]

And yes I am willing to put my money where my mouth is. I wouldn't buy it myself if I didn't do the research first. I am just waiting on the money. 

[Volvo farmer]

Well, I think my point was the video more so then the product. The video covers everything from tab wire, bus wire, diodes to what he uses to seal them. Its not like its difficult to see how it would be significantly easier then the million other posts regarding building sealed or vented frames and its not like I didn't research it first. Its a 50 dollar product that seals and doesn't block light. Its not like I recommended putting nano pilars on the solar cell that required a research department. I get your point, relax a bit. In the end I would still recommend it over trying to build a sealed cell using whatever or the many other attempts that may or may not work and at a cost of 50 dollars I would say even if it didn't work for more then a year there are many more options that won't last a year that will cost a lot more. So yes I can say with confidence that its not going to be worse then the million other options that have been tried and didn't work.

It's all good, man.  So you see something on a video, and believe the fellow making the video, and have no hesitations recommending that guys stuff, because he says it seals and does not block light.  It's pretty cool that you can say with confidence that it will work better than a million other options, even though you have never tried, nor tested the stuff. 

I'm not saying that this stuff is a bad product, I am only saying that you are talking out your ass for recommending products to DIY solar panel enthusiasts that you have neither purchased nor tested on your own DIY soalr panels. 

The cool thing is that you can get on here in a few years and tell us all how well your solar panels are working with this encapsulent and then you will have an actual data point to back up your scientific claims.

[zander1976]

First I said a million options that didn't work. Second, i have looked at more then just a video. 3rd, Do i need to have absolutely every solar panel on my roof in order to say that one product is good? 4th I am pretty sure you haven't tested every solar cell on ebay yourself to justify saying anything about solar cells or have you? 5th, I don't think people should take any bodies word for it. I am impressed that you are one of the few that have a solar cell that has worked for more then a year but I am sure that doesn't mean that everybody should stop trying new things because you have the answer. What was the total cost of your protect? Where are the datasheets on the performance each year that are scientifically documented? Can you duplicate the process? Can others or do you have a special glass shop that is willing to go out of there way?

A quick google brought up this paper but there is a ton more (The dude in the video wasn't even selling the crap, he just uses it):
http://ncnc.engineering.ucdavis.edu/pages/equipment/Sylgard_184_data_sheet.pdf

Don't start a sentence with "Its all good" and then continue on. I edited my post to remove any harsh tones since I thought I miss-read you. Don't get on some high horse because you built a solar panel and it worked for a few years. If you built the first solar panel I would say wow, but since you got some basic knowledge about putting something together and by some fluke you got it to work doesn't really qualify you to jump all over anybody else like you have cured cancer or something.

[zander1976]

As far as the video goes, I do recommend it to a new person. It covers how to tab all your cells together, what diodes are, what bus wire is and all the little questions that come up like what how do you connect them together and why is it 12volts and just about every question you will run into building your first solar panel. I would say that is something worth having a look at.

[JR]

Hi guys!

Ok, I'm thankful for giving me straight information on DIY panel drawbacks. I've decided that it's worth the extra money to buy factory made panels. It takes a part of the funfactor away from this, but if "almost" nobody have had a success with home built panels, why would I be any different? 

Now I have yet another problem. Should I choose poly- or monocrystalline cells? Google doesn't seem to be any help. Some say mono is superior because of better efficiency and better in low light conditions, but some say poly gives a much better wattage if the panel is partially shaded and the efficiency is about the same as mono in clear sunlight too. Confusing to me. What do you experts say?

[zander1976]

Mono are more efficient and poly are cheaper. So its really up to your space and power requirements. If you have lots of space and then go with poly or thin-film. If you are looking for really high output like the 230watt panels then you will need mono.

[ghurd]

Mono are more efficient and poly are cheaper. So its really up to your space and power requirements. If you have lots of space and then go with poly or thin-film. If you are looking for really high output like the 230watt panels then you will need mono.

Not sure I agree with that.

If mono is so much more efficient, then how come I could get a 90W poly in the same 'space' as a 70W mono?

And I don't think typical thin-film is a real option in a real system.
G-

[JR]

Mono are more efficient and poly are cheaper. So its really up to your space and power requirements. If you have lots of space and then go with poly or thin-film. If you are looking for really high output like the 230watt panels then you will need mono.

Actually I could get mono for cheaper prize than poly. Is it true that poly works better in half cloudy / half sunny weather (don't know the right word in English) and in indirect sunlight? Several Finnish websites claim that and they also say mono is more vulnerable if the panel is partially shadowed (just one leaf on a panel might prevent it charging any power at all?). I'm getting so much mixed information I don't really know what's true and what's not..

[zander1976]

Interesting, good to know. Sorry for the mix up. It was at one point more expensive to produce monocrystalline.