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Homemade Panels
By pyrocasto, Section Solar Posted on Tue Jan 4th, 2005 at 07:41:17 AM MST
A few questions from the noob panel builder...

I emailed engineroom on ebay about a few things and he brought me to this site. It's good to find other people that enjoy the same things.
Also, since I just got here I havent had the time to sit down and go searching for all my questions unfortunantly. I wanted to know if there was anything wrong with building your panels out of wood. I havent even had the time to find what everyone else uses.
I've got 3/4" plywood base, with 1" rails/walls. With the cells connected to a piece of 1/4" ply so I can remove them easily without having to take the heavy panel itself. Instead of siliconing the glass on, I've use a rubber gasket and angle aluminum to hold it down.
Anything wrong with that?
And... Does anyone know about how much(if any) light I can reflect onto the panel before I melt(break) it?
I have some pictures of the whole setup and was putting together a "how to" website when I found this. I'll be sure to post them and see what yall(from NC, sorry) think.

Homemade Panels | 15 comments (15 topical, 0 editorial)

Re: Homemade Panels (3.00 / 0) (#1)
by hiker (hiker.wild[at]yahoo[dot]com) on Tue Jan 4th, 2005 at 01:28:27 AM MST
(User Info)

eddie creech?
kently?
know em ?
WILD IN ALASKA

Re: Homemade Panels (3.00 / 0) (#2)
by picmacmillan (rmacmill@sympatico.ca) on Tue Jan 4th, 2005 at 07:24:25 AM MST
(User Info) http:// www.frecklefarmloghomes.com

hello pyro.......first of all i would have some reservation about using wood for a couple reasons, it's bending moment properties and it will swell when wet......we use glass on both sides...go to this very informative site Http://www.internetfred.com and click on solar....internetfred has a pretty good page on it.....i think from an engineering standpoint if you had enough temperature to melt glass, you would certainly melt the cells themselves or the lead wires......although i have been shown that there is a wane or bow in glass sheets that have been exposed to the elements long enough. below is a picture of a panel ready for wiring...i have used sticky foam spacers but it has been suggested to use wood spacers.....again i have reservation personally about using wood as it will swell with moisture....some are going to fill the completed panel with oil to prevent condensation, but i am not sure at this point if this is feasable....i guess thats why we are testing....anyhow.....have a good one......pickster

http://www.frecklefarmloghomes.com

Re: Homemade Panels (3.00 / 0) (#3)
by DBGenerator (dbrick3@yahoo.com) on Tue Jan 4th, 2005 at 08:02:43 AM MST
(User Info)

I originally got to this web site because I was interested in wind generators. I think solar panels are cool, but figured I would never bother with them because of the cost verses the power you get from them. A 45 Watt panel is about $250. There was a mention of $35 per pound. What does that come out to in watts per dollars? How many panels do you get in a pound?
Dave

[ Parent ]

Re: Homemade Panels (3.00 / 0) (#4)
by picmacmillan (rmacmill@sympatico.ca) on Tue Jan 4th, 2005 at 08:08:52 AM MST
(User Info) http:// www.frecklefarmloghomes.com

i have figured it out to be .75 cents per watt....and we had some expensive shipping to canada(this is included)....take care....pickster
http://www.frecklefarmloghomes.com
[ Parent ]

Re: Homemade Panels (3.00 / 0) (#11)
by pyrocasto (pyrocasto at hotmail dot com) on Tue Jan 4th, 2005 at 07:56:09 PM MST
(User Info)

Just got a first version of my how to build solar panels(my version at least).
http://pyronet.50megs.com/RePower/Homemade%20Solar%20Panels.htm

If you will take a look and tell me if there is anything I got wrong. Or if any of the idea are bad ones.

I really want to know how you repair your panels if a cell breaks. Someone help me out there, since I've been using twice as much tabbing/ribbon, and time...

[ Parent ]

Re: Homemade Panels (3.00 / 0) (#5)
by RatOmeter on Tue Jan 4th, 2005 at 08:16:53 AM MST
(User Info) http://www.rato.us

Does anyone know about how much(if any) light I can reflect onto the panel before I melt(break) it?

Don't worry about melting it. If you're planning on concentrating light on the panel to increase the output, your main concern should be shedding the additional heat to prevent the output from dropping. The efficiency of the cells decreases significantly with increasing temperature. Example: Exposed to full (but somewhat indirect) sun in the winter, you might expect to get more output than in full, direct sun in the summer.

I tried concentrating light onto 4 small, seriesed cells from radio shack. On a sunny summer day, in direct sunlight, I got about 2.6 volts max, open voltage. Using 2 flat mirrors to concentrate the sun's rays, I got a momentary increase, then an abrupt decrease to about 2.2 to 2.3 V. After removing the mirrors, the output gradually returned to its prior level.

Next, I laid the cells directly (thought not entirely flush) onto a block of ice (those bags of gel stuff you put in coolers) and repeated the experiment. Got slightly better performance, but in general, the result was the same. I believe I was only getting good spot cooling; if the backs of the cells could be flush against (with heatsink compound) a water cooled heatsink, you could probably gain some advantage... but at what price?

Re: Homemade Panels (3.00 / 0) (#6)
by pyrocasto (pyrocasto at hotmail dot com) on Tue Jan 4th, 2005 at 09:30:40 AM MST
(User Info)

Thanks for the comments. I know that's wood swells when it gets wet, and it also rots. That's why I coated everything in fiberglass resin to hopefully keep moisture out.

Since cells do better when cool, would it be any use to put a small fan or two(like in your computer) in the back of them, which could be ran by maybe a small cheapo panel?

[ Parent ]

Re: Homemade Panels (3.00 / 0) (#7)
by bob golding (photoman290 at yahoo dot com) on Tue Jan 4th, 2005 at 01:22:06 PM MST
(User Info)

hi, think you will start to hit the law of diminishing returns with fans. better to use some sort of passive cooling if you can. i dont think the losses are too much to worry about unless you are really tight for space or designing them for something like a electric vehicle. just use as many panels as you can afford.

bob golding

[ Parent ]

Re: Homemade Panels (3.00 / 0) (#12)
by iFred (ifred2006@yahoo.com) on Tue Jan 4th, 2005 at 09:57:11 PM MST
(User Info)

What do you mean you coated everything in fiberglass resin??????
How thick?? how?

>> all energy used to produce this comment or post came from solar and wind energy! It works!
[ Parent ]

Re: Homemade Panels (3.00 / 0) (#14)
by pyrocasto (pyrocasto at hotmail dot com) on Wed Jan 5th, 2005 at 01:10:22 AM MST
(User Info)

Yeah fred, I bought some Fiberglass Resin at Lowes. It comes in metal containers in the paint section, and is pretty thick. Not bad to work with, with a paint brush though.

I just posted my section I've worked a little on at my website, here's the link again.

http://pyronet.50megs.com/RePower/Homemade%20Solar%20Panels.htm

The resin drys hard like fiberglass/plastic(withought the matting/fiberglass cloth. Should seal out all moisture and air, but I'll have to finish it up and do some tests.

[ Parent ]

Re: Homemade Panels (3.00 / 0) (#10)
by Ungrounded Lightning Rod on Tue Jan 4th, 2005 at 07:52:05 PM MST
(User Info)

You should check current, too.

Current is mostly proportional to the amount of light (number of photons creating electron/hole pairs). Voltage is mostly proportional to temperature (width of bandgap minus thermal energy in electrons in the lower level).

So while raising insolation with mirrors will have little effect on the voltage (other than lowering it by heating the cells), it will boost the current, which will stay boosted.

Solar panels typically have three or so extra cells so they'll still have enough voltage to charge batteries on hot sunny days. That's why they have voltage ratings significantly above the batteries they charge (and thus both need charge controllers or automatic dump loads to prevent overcharging and deliver less than the rated power in actual battery-charging service.)

One problem with concentrators in some of the early experiments is that the extra sun heated and discolored the material bonding the cells to the glass, causing it to darken and absorb much more of the light, reducing the life of the panels and making the concentrators counter-productive. I think they abandoned them, though, because the cooling issues reduced the effectiveness of the concentrators to the point that it was cheaper per watt just to use bigger panels and simpler array designs.

(Most of the designs I've seen on the board so far, other than the oil-filled one, look like they'd have even worse cooling issues than commercial panels.)

[ Parent ]

Re: Homemade Panels (3.00 / 0) (#15)
by troy on Wed Jan 5th, 2005 at 10:18:54 AM MST
(User Info)

If you ever overheat the silicone cells by concentrating the light on them, even once, you run the risk of damaging them forever.
Are you sure, absolutely sure, that your cooling system will NEVER allow them to over heat???

That is not a trivial task.

Good luck and have fun!

troy

[ Parent ]

Re: Homemade Panels (3.00 / 0) (#8)
by tecker on Tue Jan 4th, 2005 at 03:30:47 PM MST
(User Info)

Heat sinks on the bottom

Re: Homemade Panels (3.00 / 0) (#9)
by Joel on Tue Jan 4th, 2005 at 06:09:52 PM MST
(User Info)

I'm debating on trying a water-heat-transfer tie-in on an experimental panel. Should wisk some of the heat off the cells and lower my hot-water electric bill (next hot water tank will be an on-demand).

Joel

Re: Homemade Panels (3.00 / 0) (#13)
by ghurd on Wed Jan 5th, 2005 at 12:17:19 AM MST
(User Info)

I would advise against reflecting extra light to the panels. It will degrade the cells. They have an R value, so the front of the cell will get hotter than the back.
They are made to last, be efficient, and work for a long time, under the situation they will be exposed to, like one sun. Just one.
If the silicone could be doped to work better and cheaper, they would do it.
My 2 cents.
G-

Homemade Panels | 15 comments (15 topical, 0 editorial)

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