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image.jpgimage.jpgimage.jpgimage.jpg We have small off grid set up. Husband was given a large quantity of solar clear glass with 200 cells that have clear glass cover. No idea how old the panels are, manufacture ect. Wondering if anyone recognizes? We are in San Diego California. Looking to expand our current set up. We tested w/multi meter got 49 DCV and 4.1 mA that was with late day sun about 4pm PST. How are these type panels best installed ? Set up? How many watts are they ?
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That's a pretty unique find. Those seem to be concentrating PV panels. The lenses on the front help focus light onto the smaller cells so that you can absorb light across the whole surface using less silicon.
Unfortunately I don't see any identifying info on them. I don't think anyone makes them anymore with the price of silicon dropping so much. -
Looks like the front surface may have Fresnel lenses. Google "Fresnel PV panel".Comment
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They are concentrating panels. They absolutely need a good two-axis tracker - and those are fairly expensive.
Note that you will not get accurate voltages/currents unless they are pointed directly at the Sun. Also, such panels typically use multijunction cells, so they will likely have different electrical/temperature characteristics than your standard silicon cells.
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Depending on the lens concentration, they may not need to be in a tracking situation, at least not as we think of trackers today.
If the distance from the lenses to the receivers (the solar cells) is less than max. possible - which looks likely - the concentration ratio will be less than achievable (but still >1.0), but that concentration ratio will be less than the lenses' max. possible concentration ratio, which actual ratio, among other things, is f(distance from lens to receiver). With that distance small (small that is, relative to the lens aperture) some concentration will be achieved, but less than max. possible. That lower concentration ratio will also keep the need for, or degree of, aux. cooling down. The practical result (downside) will be a smaller acceptance half angle for the whole device than is achievable with a standard panel (In general, the smaller the acceptance half angle, the higher the concentration ratio possible, and conversely). For lower acceptance half angles the result will be less energy collected at higher incidence angles, but with less energy usually available at those angles, it'll not matter a whole lot - at least that's what most of the thinking comes down to. That loss at higher incidence angles the can be partially offset to some extent by using a CPC (compound parabolic concentrator, or "crab's eye") type concentrator - sort of a nitch application from the past and where these panels may have come from in the first place. The CPC concept winds up looking a lot like linear parabolic concentrators that have a fluid carrying pipe at the focal point, but the CPC has a wider (larger) half acceptance angle and a larger focal line which allows for the elimination of most or all need for tracking, but with the penalty of reduced concentration ratios.
Using a Fresnel scheme together with some non focusing concentration schemes like CPC's was justifiable back when solar cells were very expensive and thus allowed more $$ spent on other components from an economic standpoint if those things allowed fewer expensive components (solar cells) to be used. I suppose some SPC's may still be in use today, but with the price of cells ~ an order of mag. less than when CPC were all the rage, I suspect their time has passed. Hence (maybe), used Fresnel panels on the cheap.
As for using these as a possible adjunct to an existing array, I'd wonder if it's worth the effort for anything more than curiosity or a hobby.Comment
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Agreed. However, based on his tests (approximately 1sq meter panel outputting .2 watts in full sun) I suspect they have to be oriented pretty accurately to get a reasonable power output. (Or they are completely trashed, of course.)
As a side note, two manufacturers at SPI this year were showing CPC's focusing light onto both sides of a bifacial cell. They were claiming efficiencies of 15% even with the losses from the reflectors and the higher temps.That loss at higher incidence angles the can be partially offset to some extent by using a CPC (compound parabolic concentrator, or "crab's eye") type concentrator - sort of a nitch application from the past and where these panels may have come from in the first place. The CPC concept winds up looking a lot like linear parabolic concentrators that have a fluid carrying pipe at the focal point, but the CPC has a wider (larger) half acceptance angle and a larger focal line which allows for the elimination of most or all need for tracking, but with the penalty of reduced concentration ratios.
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Wow! Thanks to all who have contributed. I am very impressed at the knowledge level here. So, I looked up "Fresnel lens" that is exactly what the glass covers are. I don't know if it matters to actually ID the panels (figure out the manufacture ect.). I think thou I need to figure out what the PV panel watts are. Like I know my husband told me the current American made standard solar panel (we bought a couple years ago to hook up to our off grid set up) are "260 watt panels" we have two of them mounted on top of our 5th wheel trailer, as we build our little house. I think we need to test these CPV panels in strong full sun at high noon. I will attempt that today, I also would like to know how I can figure out what "watt' these panels are, so if we use them in a set up we can match the controller correctly. I can really drive you guys nuts when I tell you that he bought 10 UPS batteries @ 75.00 each. He did not know what "UPS" batteries were, neither did the guy selling them at the recycle place apparently. So these are 2012 large UPS batteries, that came out of a warehouse (400 were available, he bought 10) they are (North Star NSB 12-590FT) I have done some reading about these UPS batteries in the threads on this site, we have set up 8 in a "series and parallel" and hooked them to our two panels, from my research on this site it seems that the issue will be only longevity due to they are not designed to cycle up and down but used only as a back up uninterrupted power source with large capacity for large surge of power. So our daily charge up, then down will maybe only go for up to 200 cycles, anyway I should take the battery discussion to another topic under batteries. Thanks for everyone's help and comments. Great forum!Comment
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One last thing about the background of these CPV panels that we got for free. The guy has about 200 of them. He traded some mechanic work for them or something, when my husband asked why he got "all 200" the mechanic stated "I was going to try and harvest the gold that is in the chip" so, now my question is... has anyone heard of such a thing? Harvesting the teeny tiny amount of Gold that is apparently inside each one of the 200 cells on each individual panel?? I've heard of Gold scraping from electronics thanks to finding some YouTube videos, but nothing that shows harvesting gold from old solar panels.Comment
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Issues there:
1) 6 year old batteries may not have much life in them. It depends on how they were treated. If they were below 12 volts when you got them it's likely they are almost completely dead.
2) You are correct on the characteristics of UPS batteries. (They are likely gel.) They cannot be maintained like flooded cells are, and don't last long under cycling conditions.
3) It is worth noting that Trojan T-105's can be had for $100 new at a place like Costco and typically last much longer than used UPS batteries. And they are flooded, so they are easier to maintain and get a reasonable life out of.
With that being said, those UPS batteries may be a good way to get some experience on batteries, so that when you get a second set they will last that much longer.Comment
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Generally, PV panels do not include gold in the cells or contacts. Gold is used where parts are exposed to air, and since panels are sealed, no need for gold.
Perhaps some of the better MC4 connectors are gold plated, but only enough to reduce corrosion, the chemicals to harvest the gold, will cost more that the gold recovered. That's why so many "reclaimers" work with a blowtorch, hammer and over a creek.Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-ListerComment
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An output current of 0.0041A is so small (for something that size) as to be useless. Something
a couple orders of magnitude more would be reasonable. Try the full sun current measurement.
My impression of MC4 connectors, is the cheapest contact technology is made big enough for
the PV currents, and they are only saved from an early corrosion death by a completely sealed
cover. Gold doesn't really fit into this picture, I have only seen it on both mating surfaces. I am
pretty sure the typical MC4 contact should not be mated to a gold contact, hence none may be
gold plated. Bruce RoeComment
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Understood.
If the output of any one panel is a fraction of a W, I'd bet that panels are mostly shot. Even facing away from direct sun would net ~~ 5-10% of STC output if things were operating in some fashion. Might be something wrong with the testing too.
As for CPC improvements and bifacial panels, Bifacial flat plate solar thermal collectors have been around for a very long time, at least as far back as the early 20th century (see, C.V. Boys' modification of Shuman's design in Egypt, 1912. They often used planar or parabolic mirrors on either side of an E-W aligned collector arrangement with the flat plate collector's surface normal being mostly or ~ perpendicular to the beam radiation, that is, the collector was generally edge on to the sun. The CPC adaptation generally helps even out the solar flux across a PV panel as the sun's elevation changes during the day - planar mirrors would over/under shoot the full illumination of a panel most of the time, and parabolic throughs over focus creating what amounts to the same problem of unequal irradiance over an entire surface that amounts to the same problems as shading for PV.
I bet that panel arrangement would look rather funky on a roof. I'd also expect wind loading would be a bigger consideration than for more common arrangements. I'd also guess that wind loading and the attendant design considerations are something the peddlers of such equipment had not considered. Maybe more "you could just do this and 'poof' a miracle happens" non-engineering.Comment
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Perhaps.
However, while evaluating some PV cells from Alta Semiconductors, they warned me that their early prototypes had high leakage currents. And while in full sun they produced close to spec, at lower levels of illumination the leakage dominated, such that they went to almost zero production at 25% insolation. (In other words, losses were not linear compared to insolation.) If that's the case here, and the cells are designed for (say) 5 suns, then they may see almost nothing unless the cells are somewhat near the focal point.
Although from the pictures shown so far, "complete failure" is a not unlikely possibility.
Yeah, I asked one of them about that. They said that they were aiming for applications where light weight was needed, since the reflectors were very lightweight. I have my doubts as to the practicality of that design, although I am glad people are trying out things like that. Try things like that 20 times and fail 19 times - but that 20th time you might get something new and useful.I bet that panel arrangement would look rather funky on a roof. I'd also expect wind loading would be a bigger consideration than for more common arrangements. I'd also guess that wind loading and the attendant design considerations are something the peddlers of such equipment had not considered. Maybe more "you could just do this and 'poof' a miracle happens" non-engineering.
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On the lower output, I'm mostly ignorant of how lower irradiance could cause leakage so I'll keep my mouth shut about it rather than confirm my ignorance. FWIW, if D.C. leakage has something to do with it, in my book, that would make for an unmarketable design, and it seems someone actually may have bought and paid for these panels once upon a time.
On the weight business, to me, that sounds like ignorant B.S. from peddlers who know little to squat about what's required for design for wind loadings. For starters, dead weight is usually of little concern in PV applications relative to the requirements for wind loadings. And for panels that are equipped with what amounts to sails on either side of them, wind is even more of a concern - not to mention the weight added by the reflectors' supports that will be required to add rigidity to the reflector assembly, and consideration for anchorages and attachments.
As for failing 19/20 times - everyone gets lucky 1X/awhile, but unless I could document why the 20th time was successful and then repeat the success more than once or twice after that, or better yet consistently, I'd call a one off successful trial a fluke.
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