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Solar Panel Pricing - Large vs. Small


By che, Section Solar
Posted on Sat Feb 18, 2006 at 04:10:25 AM MST
Why do small solar panels seem to have higher W/$ than larger ones?

After reading all of the related posts I could find, I'm still fairly confused by the current solar power per dollar situation.  I'm shopping for low wattage panels, and was initially horrified to see that 10W panels often are advertised for $100.  Seeing that people pay $10 per watt really freaked me out:  I only need a couple watts, but I certainly didn't want to pay $20 for such a tiny power supply.
Then I started looking at bulk pricing for small broken cells.  The price dropped to $1.60 per watt by some advertisements.  But surely there was a catch, probably these weren't too useful...

Then I started looking at small panels at siliconsolar.com.  Their small panels finally made me breathe a sigh of relief:  1.2W panels at $2.88/W, and 2.3W panels at $3.70/W.

By now I was noticing a trend:  The more wattage you want, the more solar panels seem to cost!  This seemed rediculous to me by comparison with any other market.  I don't see why there would be dis-economies of scale in solar panel production.  In fact, I'm sure I'm just missing something.  But I can't figure out what.

I was again stumped by this comment from an apparent expert at otherpower.com: "The best current deal on new 50 watt solar panels is about $4.25 a watt--$212 for a 50 watt panel, in quantity."  How is it possible that I am finding much better value in relatively tiny, small-quantity pricing?

Can someone explain all this to me?  Is there something wrong with these smaller panels?  Or is it a question of false advertising?  I know that one can generally expect only 80% of the rated output, but unless the percentage is much lower on some of these panels I'm seeing, then the pricing doesn't make sense

Solar Panel Pricing - Large vs. Small | 6 comments (6 topical)

Re: Solar Panel Pricing - Large vs. Small (3.00 / 0) (#1)
by ADMIN on Sat Feb 18, 2006 at 12:04:41 PM MST

It's because of the other important factor in selecting solar panels -- Watts per square foot. The cheap panels you are referring to from that garden light supplier are made from amorphous silicon, which is much cheaper but also much less powerful than crystalline and semi-crystaline technology. So you'd have to cover a much larger surface area with those to make the same power as a normal $4.50/W panel used for powering entire homes--and assuming you had the extra south-facing space to do this, you'd have to deal with a whole bunch of little electrical connections, mounting racks, and paralleling J-boxes....a wiring and reliabilty nightmare.
ADMIN



Re: Solar Panel Pricing - Large vs. Small (3.00 / 0) (#2)
by DanG on Sat Feb 18, 2006 at 02:57:33 PM MST

$5, $8, $10-per-watt gets a 30 year warranty along with the panel which should not be confused w/ 15 or 90 day warranties; disposable vs. non-disposable, its your choice!



Re: Solar Panel Pricing - Large vs. Small (3.00 / 0) (#3)
by ghurd on Sat Feb 18, 2006 at 05:45:44 PM MST

Those are bare cells. Not Panels.
Half volt. No wires, connections, framing, weatherproofing, terminals...
Its going to take 36 cells for 12V.

The 1.2W for 12V at 2.2A needs $124 in cells. The 2.3W needs $306 for 12V.

Also. They have the "watts" figured at open circuit volts and short circuit amps.
A far cry from industry standards. Sounds like a dishonest representation or plain stupidity.
Example, a GE 50W 12V 2.9A UL and CE listed panel I can read from here, would be 72.6W using siliconsolar's rating system!  (22Voc x 3.3Isc = 72.6W)
Note that 2.9V x 12.6V = 36.54W.

Maybe I didn't look in the right spot.
G-

Ghurd.info



Re: Solar Panel Pricing - Large vs. Small (3.00 / 0) (#4)
by che on Mon Feb 20, 2006 at 12:51:11 AM MST

Wow.  It's sort of amazing how much misunderstanding of this technology there is even from people who post on boards like this.  Way to burst my bubble with the half volt stuff - I certainly didn't notice that.  So what's the cheapest 1 watt 12V panel in bulk?  2W?  Where do you shop for complete small output panels in bulk?

[ Parent ]


Re: Solar Panel Pricing - Large vs. Small (3.00 / 0) (#5)
by ghurd on Mon Feb 20, 2006 at 07:27:03 AM MST

"Bulk"? Not sure what you mean. 10 or 10K pieces?

Harbor Freight has red plastic 1.5W 12V amorphous silicon PV for $20 thats usually on sale for $10 or $12.  More of a toy. Has some use in places where if (when) it fails, its not a big deal. Charging AAs, or maintaining 7AH batteries for LED bulbs...

VW ships cars with a 3.2W PV. Mine all test out in real life to 3.8W. Nice quality PV, but its not exactally weatherproof as is.  Newer ones have a built in 12V charge controller, in the plug.  VW doesn't sell them, but they might give you one. They are all over EBay.

There is / was one company importing a 'real' 12V 2W PV.  Very nice. Last I knew, large quantity wholesale was about $40 each! Ouch.

G-
Ghurd.info
[ Parent ]



Re: Solar Panel Pricing - Large vs. Small (3.00 / 0) (#6)
by Clifford on Wed Feb 22, 2006 at 11:12:17 PM MST

I've wondered about taking highly broken solar cells...

Making small rectangular cells from the big ones...   Say, making a bunch of 1"x3" cells out of what was once 3x6 cells.

Anyway, cut them to a regular size and shape.

Then, augment them with window screen if necessary...  to put together small, high voltage panels....

-------

As far as the watts and $$$ thing.
It has been a puzzle for me too.

Say one wants to make a "collection" of panels, purchasing them one piece at at time, then shipping also becomes a factor....   $20 shipping on a 20W panel increases the cost by $1 / watt.

Anyway, I would assume the high prices for small panels has to do with the extra cost in building, handling, and distributing the smaller panels vs doing the larger bulk orders (which often also involves multiple panel orders).

And...  say you are doing a 36 cell panel.  The interconnects might be the same effort for a 5W - 36 cell panel as a 200W - 36 cell panel.

Now, I am seeing some fiberglass backed, epoxy coated small panels every once in a while....  still kind of expensive, but I assume they are easier to make and transport than the regular framed panels.



Solar Panel Pricing - Large vs. Small | 6 comments (6 topical)
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