cheap solar cells on ebay

[Evoforce]

Anybody check to see WHO is making those Solar Panels ???

I recently learned, the Solarex Panels I used to sell, was bought out be BP. ??? MOST Solar panels are manufactured by an Oil Conglomerate side business. MOST Energy supplied is owned by the same OIL Conglomerates. THEY Own the Govt's, so to speak. ??

I would be interested in knowing WHO in Germany is making the cells we bought ?? OTHER cells, of the same size, are made in Asia ??? China ??

Only way to get off the Teat of Oil, is DIY.

Exactly!!!! Oil and gas and utility companies and plenty of other "super" corporations. And for those who don't own solar manufacturing companies outright, they are heavily invested in so called "green" stock. If you had the capital, wouldn't you? Anyway... for you Harold, DYI might be viable, in the States they make it imposible to compete and after all things are considered. They win so far. We have to change plenty of laws here to make it possible to level the playing field. At least homeowner associations now, by law, have to allow solar. Sure, if you want to just do a small experiment, noone will stop you. But anything really worth while, you cannot get building permits, you cannot tie into the grid, you cannot get insurance and most homeowner policies will drop your insurance if they find out DIY, you have to remove anything you DIY without permit (but required one) upon selling you property for liability reasons, you cannot sell your own panels as a business without getting them UL rated. You cannot get a government tax break, You cannot offer a potential customer a tax break opportunity. And sorry to say the list goes on... The truly sad thing is, big business has our government in it's pocket and most of the laws are made in their favor, because day in, and day out, they are lobying to take our money from us. It just makes me sick..absolutely sick...AND ANGRY!

 

[Harold in CR]

Hence, yo vivo en Costa Rica

Y'all would be really surprised how many Americans live down here. I got tired of all the crap you are posting about, many years ago. People are Sheep. They follow the leader, over the cliff ??? I choose to take care of #1 and allow my results to possibly help others. Without Forums like this, lots more people would be trapped in a non-compliant environment. I despise most Govt. employees, from Presidents (some) right down to the clerks of Townships. No one has Cajones, anymore, to raise hell with the CODES, that are set by Feelings, rather than helping the very people that pay taxes for the benefit of all the people.

I say, if you don't like my Wind Tower, DON'T LOOK AT IT.

I believe MOST laws are passed to satisfy Insurance Companies. Try to do ANYTHING without Insurance. When I was a kid, it was hardly heard of. Down here, What's Insurance ?? You fall into an open hole in the sidewalk, and you want to sue someone ?? :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: :lol: GOOD LUCK :lol: :lol: I'm about to turn 68.

I'm not preaching to the choir. Like I stated earlier, I just call 'em like I see 'em.

My Buddy I used to visit down here, before he passed away, always said " If you want to live in Paradise, you have to be willing to suffer". John and I are really suffering.

 

[veloman]

Are these cells really 17% efficient? That would mean 170watts for a square meter.

But I just figured that my 40 cells would lay out as: 24"x33" 40*1.8w=72w for 792 sq inches

A Square meter is 39.4" x 39.4" which is 1550 sq inches

So with my cells, it would only get 140watts, which is closer to 14%.

Maybe the 1000w per sq meter is a high estimate?

To charge my 36v battery, what charge controller do I need? I don't see a 36v one out there? I suppose with a charge controller, it doesn't matter what voltage my panel is, right?

 

[Jeremy Harris]

Are these cells really 17% efficient? That would mean 170watts for a square meter.

But I just figured that my 40 cells would lay out as: 24"x33" 40*1.8w=72w for 792 sq inches

A Square meter is 39.4" x 39.4" which is 1550 sq inches

So with my cells, it would only get 140watts, which is closer to 14%.

Maybe the 1000w per sq meter is a high estimate?

To charge my 36v battery, what charge controller do I need? I don't see a 36v one out there? I suppose with a charge controller, it doesn't matter what voltage my panel is, right?

1000W/m² is the generally accepted value for the amount of power falling at the Earth's surface in full sunlight (no cloud). I'd guess that you would get higher values near the equator, or at altitude, and lower values at Northern lattitudes, but the 1000W/m² figure is used by the solar industry as a standard way of assessing solar cell performance.

I bought some of the eBay cells and the couple I tested (without glass) were around 16% as far as I could tell. I was only able to use a light meter to estimate the solar power falling on the cells, which probably wasn't an accurate way to do it. The Sunflex panels I have on the boat seem to perform about the same, as far as I can tell. I'm pretty sure that all these cells sold for DIY purposes will be around the same efficiency figure, somewhere around the 15 to 17% mark. A glass, acrylic or UV resistant polycarbonate front panel will reduce efficiency a bit, as even the best solar panel grade glass will only transmit maybe 90 to 95% of the available light energy.

If you want to charge a 36V battery then your best bet is to connect enough cells in series to get a voltage high enough to drive a BMS or charger circuit. At a guess I reckon that you want to aim for a panel open circuit voltage of around 55 volts (92 cells in series) or so, which will give a panel working voltage under load of around 46 volts. A 36V nominal battery will be somewhere around 42 to 43V on full charge (if it's lead acid) or around 44V if it's a 12S LiFePO4 pack. You'll need a bit of voltage headroom to drive the charger properly.

Commercial panels use 36 cells for a nominal 12V panel, which gives an open circuit voltage of around 21V or so and a nominal working voltage of around 17 to 18V. This allows enough headroom for a regulator to keep a 12V nominal (maybe 14V or so fully charged) lead acid battery topped up.

Jeremy

 

[PedalingBiped]

The new generation of solar is using Fresnel lenses. The lenses are cheap compared to the cells.
Put a 12X12 fresnel above a 6X6 solar cell and you get twice the power.
I've been following this company for awhile, out of Oz
http://pesn.com/2006/02/01/9600228_Sun_Ball_Released/

 

[Jay64]

The only thing that makes buying a system rather than making a system worth while are the grants/rebates and selling back to the power company, that you mentioned. However, that can be a fickle thing. With our government possibly changing every 4 years and attitudes about things becoming more divided everyday, the grants/rebates can disappear real quick. And a lot of places it is nearly impossible to get a "new construction" grid tie in. Some of the power companies are refusing to take more pay in projects. They are claimng they don't have the resources to accept that much incoming power. I do get your point, but I grew up off the grid. I would rather build it myself, and be totally self sufficient, then rely on corporate/government control, even if it costs the same amount of money.
http://greenpowerscience.com/ has done a bunch of work with fresnel lenses. They have a lot of interesting stuff. Actually, I just found out recently that they work in my general area. I want to see if I can go check out some of their stuff sometime. I want to get one of my builds polished off so I can have a "barter chip" to visit with. :lol:

I just realized I have 13 50 ah SLAs laying around that I am no longer using for EV use, I could build a nice battery bank with that.

 

[Harold in CR]

I emailed that outfit, Jay. I wanted a price on a Fresnel lens WITHOUT the frame, so I could carry it back on the plane. 2 emails and NO contact back.

Might they be creating more heat on those cells, using the Fresnel ?? As I wrote above, I want one to play with down here.

On another note, what is the comparison of capacity between a Golf car battery, and, those RC Batteries, like Hobby City is selling ?? Cost wise, maybe a little higher for Lipo, but, YEARS more service possibly ?

Anyone want to do a cost-capacity-lifetime comparison for us ?? I think it might be interesting. Figure 12V packs and 2 golf car batteries, as equal storage devices. Which would be a better system, over 10 years ??

Personally, I see nothing wrong with selling to the Power Co. at wholesale prices, or 50% of the Power Co. rates. If you have an oil well, you don't get retail prices for that crude ??

It's just that the system is for big Corps, not the bill PAYERS.

 

[Jay64]

Yeah, that is why I was thinking I would have to bribe them with some sort of electric build to get their attention. But I would think a potential buyer would also get their attention.

As for my battery bank, I got them all for just over $100, so the cost is really great.

 

[Evoforce]

First off Jay, I don't know what you plan on running with only 650 amp hours of back up battery. That is the same as 4 and 1/2, 12 volt golf cart batteries. So don't plan on having very much load on your system after dark. You could get by with a few lights though. Maybe a t.v. for a little while. Have you made sure that you have changed out all of your light bulbs first. There are consumption charts on the internet that can tell you approximately how much power items in your household need. And to Harold, you are correct in questioning the wisdom of using a fresnel lense on photovoltaic. Do not do it. You could use it on a solar water collector but you would need a tracking device to keep the focal point focused on your heat target. Fresnel lenses can be very dangerous so be careful! This is my battery bank for my house. 1/2 of them are golf cart batteries 140 amp hour each (reserve) and the other half are deep cycle marine 125 amp hour each (reserve). Also these are lead acid not SLA. It is also not good to use a normal car battery.

 

[Harold in CR]

Gotcha, Evo. I am trying to work out a system, so I can water cool the panels. Trying to not need a pump. It's a tough think.

I would rather have to need 1 more panel, than apply more heat.

 

[yopappamon]

I've just ordered some un-tabbed cells off ebay. The soldering of the tabbing should be no big deal for me, but I need advise on the panel framing.

What do you guys do for the frames? Do you build your own from aluminum angle? Can you use picture frame material? or do I need to buy something made for solar cells? Do you use the Sylgard to pot the cells? Do you have any online links for these supplies? I see ebay has the Sygard but not much for frames.

 

[Harold in CR]

Check out Metal Salvage Companies. They should have scrapped Aluminum window frames. That's what I would use. Just make it 3 sided, and slide the panel in the space that holds the glass. Then screw on the fourth side, and maybe add angles over the outside corners, for more rigidity.

I'm leaning to use GE II Silicone, that comes in caulk tubes. Thin it with Glycerine, I believe, and use that as a cheaper Sylgard. It will dry clear, so, if it seeps under the cells, it will still not hinder production.
I have info to put in this thread, but, I have to go fetch a few logs, so, I will update later today.

 

[yopappamon]

I'm leaning to use GE II Silicone, that comes in caulk tubes. Thin it with Glycerine, I believe, and use that as a cheaper Sylgard. It will dry clear, so, if it seeps under the cells, it will still not hinder production.

Interesting. That would be way cheaper than Sylgard. What about epoxy or acrylic? Or maybe epoxy over a thin layer of silicone.

 

[Jay64]

Evo, I never stated that I was going to try to run my whole house on That particular battery pack. I was just making an observation that I had that particular amount of batteries sitting around after switching out my hurricane. I would probably start off doing a small project build for recharging batteries. And build up from there.
and when I was a kid, we ran our whole house on about 6 marine batts. Granted, we didn't have as much stuff as I do now, but I fully understand about minimizing for power use.

 

[Harold in CR]

Here is the link to what I am probably going to use. It's a good read.

http://fieldlines.com/board/index.php/topic,134993.0.html

 

[yopappamon]

Harold, have you tried the silicone?

I was just googling and some have said that silicone is cured by humidity and that moisture will penitrate causing fogging. Maybe could do a glass base, pot the cells in thinned silicone, sandwich with another sheet of glass or plastic. Then seal the edges with something more moisture resistant.

 

[Harold in CR]

Epoxy is expensive. It may very well yellow. I do know that some forms of epoxy will yellow.

I sent John a copy of info from a guy that worked in the Solar panel Industry, and, has contacts throughout the industry. Let me look for that info. The guy also says Silicone OF THE CORRECT TYPE< would be probably best for DIY panels. That's good enough for me to try 3 panels.

Found that info. Read this.

Right from the Horse's mouth.

Silicon Gel for Encapsulation

On August 16, 2010 11:01 AM mountain, Keith Durand (email on file) wrote:

Hi Sterling,

I have some important information on laminating solar panels for the DIY crowd. I worked for a photovoltaic cell and panel manufacturer for a number of years. The encapsulants used for lamination were always a hot topic as the industry was dominated by EVA encapsulants which had a known "browning" problem (which may have been fixed in the past 15 years). We had a test module that had been in a desert for 10+ years, tempered glass in the front and back, and it looked brand new. I was told the encapsulant was silicon gel and that it was the best but not well-suited to manufacturing. I mention it here because I believe it may be possible to build a module with silicon gel as the ecapsulant, in your garage that would last as long as others manufactured in multi-million dollar facilities.

After leaving the PV manufacturer I worked for SEIA, then UPVG (Utility PhotoVoltaic Group).

[...] When I was the Director of the PV division at SEIA I was constantly getting calls from people on the fringe that took way too much time; something you probably have experienced. For your info only, I was employed by Mobil Solar which was sold and became Schott Solar in Billerica, MA; from there I went to DC to work at the Solar Energy Industries Assn (SEIA). Three of my friends from Mobil Solar founded Evergreen Solar.

Another method we considered for those wanting to use EVA as the encapsulant: two industrial heating pads and a bladder compressor. The uncooked panels are put between the heating pads which is in a bladder/compressor (actually two bladders, above and below the heating pads. This would heat/melt the EVA as the bladders inflate and apply pressure; the end result is a fully cooked laminated module. The industrial laminators used in module manufacturing cost $300-400k compared to about $3k for the bladder system. This could be a system for developing countries -- although I still think the silicon gel is pretty low tech for what might be a longer-lasting module.

 

[John in CR]

WRT epoxy yellowing, UV definitely causes it to yellow. Even West's formula 207 with UV inhibitor still is recommended to have a quality UV blocking varnish on top. As my UV blocker I've all but decided on 1/32" Lexan. Then I'm free to use epoxy with fiberglass cloth for strength.

I want to avoid the difficult effort of a clear fiberglass layup, so first I'll try a panel with the composite layers being:
Lexan
a thin coat of epoxy
cells
fiberglass cloth impregnated with epoxy
bottom coat of epoxy to ensure a good seal

Note that I'm not building mine for a permanent installation. They will be for mobile use, so other than making one that actually works, my to priorities are rigidity and minimum weight. If I was building one for the house the priority would be long life, so I'd just sandwich the cells between 2 panes of glass using a good silicone with no acetic acid in the cure to completely eliminate any air space.


WRT to concentrating the sun using fresnel lenses, cells are so cheap now that it definitely isn't worth the effort, especially since you would have to actively cool your cells, since heat affects both efficiency and life.

 

[Evoforce]

You have to be very careful which silicon you use, some of it is very acidic and some will turn clowdy over time. It sounds like you guys are doing the necessary research to get the job done. I like your plan of getting your frame aluminum from salvage. Make sure, those of you that have to contend will hail, that you have appropriate glass. Do you get hail in CR? Have fun and keep up the good work. A+ on the working on watercooling the panels. That is where the technology is headed. I have personally not tried to do that myself, but it makes excellent sense. Heat your water and cool your panels at the same time using the same square footage of space. Photo cells like to be cooled and the water used can provide a benefit too!

 

[yopappamon]

Has anyone used the EVA sheets and laminated the cells to a glass panel? I know ideally you would want to vacuum out the air, but would a little really make a difference? I was thinking I could make 6 - 2x3 cell sub panels. Using the 6x6" cells, the sub panels would only be 19x13". Small enough to be baked in a kitchen oven to laminate them.

I guess the problem with this idea is you would need more framing to assemble all the little panels.

 

[John in CR]

Do you get hail in CR?

I saw some pea size hail once here in the central, smog free, valley (5-6 years ago they outlawed the heavily smoking buses and made people stop burning their grass instead of cutting it, so Harold is behind the times on that one. I haven't seen that haze in years.). We just don't get the really tall thunderstorms here, but I don't know about out a Harold's place which is on the other side of the mountain range that splits the country in half.

The thought of hail or even cold rain hitting a hot panel does give me some concern about glass. The other option would be to go with one of the plastics, and accept that there will probably be some yellowing within a 7-10yr time frame. By then we should have dirt cheap PV panels available, so as long as it's done cheaply, it's not an entirely invalid approach, especially since the output will just degrade somewhat, not just stop working all at once.

 

[Harold in CR]

Have not seen nor heard hail in the 5+ years I have lived here.

I plan on regular window glass, and under that plastic of some sort, with the cells Siliconed to it. That way, if the glass breaks, just take it out, slide in a new piece and reassemble the panel. Back side of the panel, I'm thinking thin Aluminum sheet, like Printing Press sheets, IF I can find them. Use 2 sheets, and glue together with something like liquid nails, making channels for the water to run. Stick that to the back side of the cells with a thin sheet of that same plastic stuck to the cells. There is a sheet plastic, green tinted, that I may use on the back side. It's probably 6-7 mil, so, it will keep the metal from contacting the solder joints ??

EVA needs to be pressed a little, if it's put in an oven, because, I have seen it installed, on a video, and a normal heat gun used, allows the stuff to sag between the cells, but, it tends to wrinkle a bit, if it's not manipulated by hand a little. I was pretty hot on using it, in the beginning, but, tubes of Silicone are easier and cheaper, once thinned with Glycerine. It looks like hand cream consistency, or a tad more liquidey. Should pour and smear pretty well. Then place a sheet of that plastic 6-7 mil on it, and work it down a little, maybe with a layer of thin plywood, which I normally have. That would make even contact and a nice smooth surface for the Aluminum sheets ??

More as I get involved with the project. Got too many irons in the fire, as it is.

Not a lot of Aluminum window frames here, unless you think Jalousie ?? Windows. I may have to buy new frames, made to size ?? Still, 3 frames can't be THAT expensive. I want a tracker, also. That will be where the money goes. Sun is near directly over head. I got LOTS of lumber to build that with, especially BALSA. :lol: :lol:

 

[John in CR]

Harold,
What's the glass for if you have plastic under it? Also I believe that way the glass will reflect more light. I believe at each air glass interface some light gets reflected, so having the silicone directly on the glass is better. Also, I believe any air space above the cell will eventually have condensation, no matter how well you try to seal it all up. Last, your glass will break easier that way. I'd think that a sandwich of glass+silicon+glass or whatever on the bottom with the cells embedded in the silicone will be a quite strong composite layering.

 

[Harold in CR]

With the wind we get up here, sometimes, I would be afraid of the frames twisting and breaking the glass, if that was all I used. I think Plastis sheet, maybe 1/16th or so thick, stuck directly to the glass, might be rigid enough to take the twist.

I plan on having very rigid frames, but, we all know Murphy is watching.

 

[yopappamon]

The silicone wouldn't reduce the cell output if it got in front of the cell?