Solar Panel Prototypes

I realized that using tiny pieces for large panels was not at all feasible. It would take considerable time to figure out patterns that would maximize the space used by the cells themselves. A lot of solar panel area would also have been covered by the rather large copper strips, and the cells still had no good means of being anchored, as gluing each one to the foam would have consumed even more time. So the little pieces were abandoned.

A month or two later, I came upon some solar cells on eBay being sold by the pound - "cosmetic econds," the listing said. "May have broken corners, cracks, chips, slight warps, off color, etc." The description and the pictures looked promising. I also found The Otherpower Forums. Although they don't have quite as many members as the tech forums I usually visit, their loyal visitors had a wealth of information and ideas available. It seemed that others had found these eBay cells and were already building their own panels.

So with the new information, I decided to risk the purchase of a pound of the cells. Some cells cracked during shipping, so they all needed individual inspection. Packing solar cells properly for shipping either requires special shipping containers or lots and lots of time and care to prepare each cell for the harsh environment it would have to endure. I spent time over the next month researching ways of building panels, as well as possible costs. Testing of the cells during that time showed that they erformed very close to their rated specs, despite being rejects. Justification for rejection ranged from minor problems, such as tiny edge chips or silkscreening slightly off-center, to severe, like cells missing large portions of the conductive backing, or a few that had the leads soldered from the front around to the back, shorting out the cell.

Broken Cell Stack
This is the stack of broken cells that came from the first pound I sorted through. Some here are outright broken in half, but most just had hairline cracks. I found cracks by gripping every corner of the cell all at once, and lightly twisting the entire thing back and forth. Any cracks would make themselves known by making a high pitched creaking, caused by the rubbing of the adjacent edges. Close inspection revealed what kind of crack it was, and its severity.
Usable Cell Stack
Here's a stack of some of the usable cells I wound up with. It was about a 60% survival rate. I probably can still use some of the cracked cells, as a few of the cracks don't break any of the silkscreened lines, which doesn't interfere with output. However, I wanted to get as many perfect cells as I could get; I'd deal with the less-than-perfect ones later.


A month or two had passed now since the buying of the original pound of cells. I figured that these things could be used in full-sized panels without nearly the trouble of the little chips I'd been working with before. Problem was, the seller's supply was limited. So I decided to take a risk and load up on the cells while the getting was good, even though I wasn't sure if I could produce a good design for a panel. I went on a road trip, from eastern Pennsylvania to the seller's location in a town 30 miles south of Boston, Massachussets. This meant I could see the cells myself before buying, and it also meant that they would not be subjected to the rough handling of UPS/FedEx/USPS/DHL/Whatever Shipper Inc.
Net result of this trip? 60 pounds of cells that needed to be sorted through. Talk about a time consuming process...but the yields are still good. Each good cell is capable of about 1.5 watts. And the best box I've sorted thus far had a survival rate of over 90%. So at this point, I had more than enough cells to work with; it was time to draw up blueprints for a prototype panel. Head to Page 3 for the info on the good prototype (as opposed to the lousy one on the first page).

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