Be careful, the cells need to be isolated by diodes otherwise there is a possibility of fire. If one cell becones obscured by a shadow current will flow into that cell like a shorted battery(a 600mV battery) and heat up.

Posted at 4:08 am on Sep 15th, 2008 by ent

I’ve been digging around the net as much as possible for info on DIY panels and nowhere have I seen anyone mention even the possibility of solar panel catching fire!

I am in the process of building a single 130 watt solar panel from 72 3″x6″ cells (which turned out to be 3.2″x6″ so have had to re-adjust my plans slightly), it will be just over 1 meter square, using acrylic instead of glass and will be held rigid with L-shaped aluminium angle bolted to it & sealed with a silicon substance as it will be permanently outside (and here in the UK the weather is often very wet).

One thing to note about the cells used in the panel pictured (the same as the ones I’ve got) are that they are fragile as hell & as brittle as glass, I measured one to be 0.33mm thick. One of the batch I bought arrived broken (it did travel halfway across the globe) so it gave me the chance to see just how brittle it is, it’s now in several pieces and I’ve learnt to treat them with the utmost respect, thankfully the eBay seller sent me 80 instead of the 72 I ordered, which leaves me with 7 ‘error margin’ cells.

Still waiting for the tab ribbon to solder the cells together though :(

BTW if you’re wondering how the professionals put their panels together with these types of cell: http://www.youtube.com/watch?v=qYeynLy6pj8
I have a small 30watt Kyocera brand solar panel which is 25 years old, it still works fine giving out 24watts peak so the commercial ones are definitely built to last.

Posted at 7:32 am on Sep 15th, 2008 by Haku

this is a good point, here is a PDF that discusses this.
http://scholar.lib.vt.edu/theses/available/etd-11698-16389/unrestricted/Chapt_4.pdf

Jason Rollette

Posted at 7:56 am on Sep 15th, 2008 by Jason Rollette

I don’t keep up on solar technology, but I thought BG Micro had an interesting deal: http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=12269

Copper Indium Diselenide, 4.5V at 90ma from a 2×2 inch cell, for 2.50 if you buy 50 of them. So that’s about 48 watts for $125, $2.60 per watt. I’ve seen some interesting auctions on eBay for the same type of cell, might even be cheaper.

Also: please fix the comment box. Just try using it, you’ll see what we mean.

Posted at 11:02 am on Sep 15th, 2008 by macegr

Individual cells don’t need blocking (usually schottky) diodes but panels do when put in parallel to stop them trying to feed power into each other, and you can use a schottky diode on small panels to avoid having to use a charge controller. Larger panels require a charge controller to stop the battery from being over-charged.

macegr, those 2*2 inch cells are 0.405 watts (4.5v * 0.09A), 50 of them would make a 20.25watt panel for $124.50, $6.18 per watt. Not a complete bargain and not a terrible price either, but they look great for someone wanting to make a panel without having to deal with ultra-fragile cells.

Posted at 8:01 pm on Sep 15th, 2008 by Haku

Um I think the both of you are wrong on your calculations.
If you need lets say about 18 volts for charging a battery,
so if you ran 4 of these cells in series (4×4.5v gives you
18v @ 360ma) now if you ran 12 of those in parallel that gives
you (12 x 360ma) 4.32 AMPs or a panel that produces (18v x 4.32AMP)
77.76 watts with 2 cells to spare. because your not going to run 50 cells in
series, while your calculations are right haku, you dont want
a 220v solar panel.

Posted at 8:08 am on Sep 16th, 2008 by Olly

Thanks Olly I was researching that because what haku said
did not make sence to me. By the way that come out to about
137.45 with shipping thats 1.76 a watt. A 80 watt panel runs
about 400-500$ and for a 500$ 80 Watt panel thats about 6.25$
a watt. So its about a 3rd of the price. I need a beer!

Posted at 8:29 am on Sep 16th, 2008 by nemfo

olly,

Identical cells (or batteries) in series you add up the voltage. The ampage stays the same.
Identical cells (or batteries) in parallel you add up the ampage. The voltage stays the same.

4 of those cells in series gives you 18v @ 90ma. 18 * 0.09 = 1.62 watts.
4 of those cells in parallel gives you 4.5v @ 360ma. 4.5 * 0.36 = 1.62 watts.

The total wattage always stays the same no matter how the cells are joined.

If you wanted to make a panel with those cells you’d do better with getting 52 & putting them in a 13×4 grid array, wire up 13 sets of 4 cells in series, and put those 13 sets in parallel (all the pluses together & all the negatives together).

In that 52-cell configuration you’d end up with 18v @ 1.17A, 13 x 0.09A (90ma), 21.06 watts.

Posted at 12:43 pm on Sep 16th, 2008 by Haku

where did you get the cells from
and how much

Posted at 6:57 pm on Sep 16th, 2008 by 4-acre

The cells I have were bought from http://search.ebay.com/_W0QQfgtpZ1QQfrppZ25QQsassZlifestylephoto but they’ve not got any listed at the time of posting this, they were $4/cell + postage (and annoyingly + import duty, that’s rip-off Britain for ya). They must still have literally bucket loads because if you look at their completed listings you’ll see they didn’t sell all the cells listed.

Posted at 7:40 am on Sep 17th, 2008 by Haku

just goes to prove that solar power needn’t cost a fortune

Posted at 1:48 pm on Oct 17th, 2008 by Total Solar Energy

does anyone know of how to make a 130 watt panel
what size cells amps and volts what is the formula
for figureing this out first experience in solar in series or parallel tell me more live in USA GA.

Posted at 4:56 pm on Feb 2nd, 2009 by Mike Hooper

yea i found some good cells on ebay and put together a simple panel. hasn’t caught on fire yet..knock on wood

Posted at 12:55 am on May 4th, 2009 by diy solar power

I am building panels, you only need blocking diodes in series with your panel to stop the current flow in the dark!
Individual cells will not heat up enough to burst into flame, unless the supporting medium is tinder dry tissue, and even then I doubt that even here in Aussie where the sun is somewhat hotter/longer than the uk :-)
Mike

Posted at 3:03 am on Jun 11th, 2009 by Mike