Author Topic: Solyndra PV tube, what to do with it?  (Read 7977 times)

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madlabs

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Solyndra PV tube, what to do with it?
« on: May 10, 2014, 09:53:47 PM »
Hi All,

At an electronics junk store I picked up a Solyndra PV tube. Yep, that Solyndra. It's VOC is 100V and ISC is 48mA. I'm wondering what to do with this bugger. It's neat looking, about 3/4 of an inch in diameter and about 3' long. My first thought was to use it to power a light in my outhouse. I've always meant to get some super caps and make a small LED light that would run for say 10 minutes a night. How to regulate 100V down to super cap voltage would be the question. Or if I did use a battery, same issue of Vreg.

Jonathan

OperaHouse

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Re: Solyndra PV tube, what to do with it?
« Reply #1 on: May 11, 2014, 03:02:00 PM »
You can easily power a small electronic wall wart with it. The typical 5V cell charger can easily be converted to operate with 6V battery or 4.3V Li cell.

Mary B

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Re: Solyndra PV tube, what to do with it?
« Reply #2 on: May 11, 2014, 04:36:00 PM »
Had to look those up, never looked at the technology, just the fact that it was a failed company due to Chinese competition. Interesting idea...

madlabs

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Re: Solyndra PV tube, what to do with it?
« Reply #3 on: May 11, 2014, 05:41:18 PM »
So Opera, what are you talking about? Hacking into the wall wart just after the rectifier part and subbing in the 100VDC? Got any more specifics? I'm a "knows just enough to be dangerous" type. :-)

Jonathan


OperaHouse

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Re: Solyndra PV tube, what to do with it?
« Reply #4 on: May 12, 2014, 08:56:11 AM »
No hacking required.  Just connect the panel directly to the wall wart. These will still function down to about 40V and your
panels power point is likely over 70V.  Most electronic wall warts have full wave bridge rectification and polarity won't matter.
If it doesn't work, try reversing the leads.  Very rare are those that have a voltage doubler and these won't work at all.
Typical cell phone charger is 5V 1A (5W) so this is a good match for this 3-4W solar cell. A diode voltage drop and small
resistor would be enough to charge LI or Ni batt.

madlabs

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Re: Solyndra PV tube, what to do with it?
« Reply #5 on: May 12, 2014, 10:15:20 AM »
Spar,

Cool! Pity I have to go to work for my 48 hour shift, but I'll try it as soon as I get home. Cell phone chargers are 50 cents at the local thrift store.

Still wondering what to do with it. The outhouse would be OK, but I'm also thinking of maybe some whacky garden art.

Jonathan

madlabs

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Re: Solyndra PV tube, what to do with it?
« Reply #6 on: May 12, 2014, 07:37:39 PM »
And I meant to ask, have any charging circuits for li and ni batteries?

Thanks!

Jonathan

DamonHD

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Re: Solyndra PV tube, what to do with it?
« Reply #7 on: May 13, 2014, 01:20:03 PM »
Hmm, yes, I'd be on for a simple safe smart-ish NiMH charger to go with solar (and/or an Arduino implementation, since I now have a house full of ATmegas in Arduino-like boards and a fair number of NiMH AAs at 2Wh each).

(Yes Bruce, I chickened out of your suggested solution so far!)

Rgds

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madlabs

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Re: Solyndra PV tube, what to do with it?
« Reply #8 on: May 15, 2014, 11:32:37 AM »
Hey Opera, it works! I grabbed the first USB type wall wart I had handy, hooked the Solyndra tube up whichever way was handy and thar she blows! Awesome. POwered up a small project I had handy no problem.

So now I'll look for a simple charge circuit. Wish I'd bought a few of these things.

Jonathan

DamonHD

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Re: Solyndra PV tube, what to do with it?
« Reply #9 on: May 15, 2014, 03:32:40 PM »
Answering my own question above:

http://www.gaw.ru/pdf/Atmel/app/avr/AVR450.pdf

Rgds

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madlabs

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Re: Solyndra PV tube, what to do with it?
« Reply #10 on: May 15, 2014, 06:00:02 PM »
This looks like a possible winner:

http://www.candlepowerforums.com/vb/showthread.php?57999-Super-Simple-DIY-Li-Ion-Rechargeable-Charger

Opera, any thoughts? Is the 5V enough overhead to charge to 4.3V for a 3.7V li battery?

JOnathan

OperaHouse

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Re: Solyndra PV tube, what to do with it?
« Reply #11 on: May 16, 2014, 09:09:08 AM »
How about a picture.  As I remember these were like fluorescent tubes that were ideal for flat roofs.  Are they full coating or 180 degree?  Anyway a single tube is more an artistic element than something useful.  Just what did it cost?  Under ideal conditions it can produce about 3W.  Without power point control it can likely only produce 1W

My attitude is that all these Li batteries are free to me.  For fastest charge and longest life a chip controller is the best.  I haven't found the chip mentioned in any of my take aparts and doubt buying one is a worthwhile investment.   I use the Chinese method of constant voltage and current limiting.  Those outdoor solar lights last for years with next to nothing for a charging circuit.    From memory those 3.7V cells have a charge voltage of about 4.3V.   For a 5V supply I would start with a diode and 39 ohm resistor in series to give about 4.3V.   Not a fast charge but if you keep current 1/30 of AH there shouldn't be damage.

Most all of these chargers use an opto isolator to turn the switcher on and off.  On the low voltage side the cheapest ones just use a zener and resistor in series with the opto LED.    Subtract about 1.7V from the desired voltage and that is the voltage of the zener.  You don't have a lot of choices at low voltage so standard diodes can be used to adjust it a little.    Better devices will use a LM431 in place of the zener.  That would allow you to adjust the voltage with a pot from about 3.5V upward.   Doing this hack would be better as it would give a precise voltage and not wast power in diode voltage drop.  You said you were dangerous so maybe the diode and resistor in series would be best.  That LTC4054 battery charging chip will cost you about $5 and good luck trying to solder to it.
« Last Edit: May 16, 2014, 09:17:31 AM by OperaHouse »

madlabs

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Re: Solyndra PV tube, what to do with it?
« Reply #12 on: May 16, 2014, 10:51:05 AM »
Opera,

Perhaps I should have said that I know enough to be REALLY dangerous. I am sure I could solder that chip, at least with a break out board. For example, I built my own hot tub controller, water system controller,etc.

BUT. I'd rather go with a diode and a resistor. Just don't want to blow up the Li batteries, you hear of that. Sounds like you are talking a shottkey diode, with a voltage drop of .7V

I'll take a pic of the tube and post it. Not at home at the moment.

Jonathan

OperaHouse

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Re: Solyndra PV tube, what to do with it?
« Reply #13 on: May 17, 2014, 06:03:22 PM »
I benched it up and you want to go with a standard Si diode for that ,7V drop so the battery isn't over voltaged.  The resistor could probably drop to 20 ohms.

madlabs

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Re: Solyndra PV tube, what to do with it?
« Reply #14 on: May 18, 2014, 02:01:28 PM »
Sounds good. I have a li 3.7V battery pack from a camera, ill try giving that a charge.

Thanks!

Jonathan

Ungrounded Lightning Rod

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Re: Solyndra PV tube, what to do with it?
« Reply #15 on: August 18, 2014, 11:50:55 PM »
No hacking required.  Just connect the panel directly to the [non-transformer type] wall wart. These will still function down to about 40V and your
panels power point is likely over 70V

GREAT idea, Opera.  I've been trying to figure out what would be a good way to deal with their oddball output voltage if I ever found 'em on the surplus market, and that just DOES it.  I've wanted to get a "panel" (several-tube assembly) or two for my travel trailer.

madlabs

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Re: Solyndra PV tube, what to do with it?
« Reply #16 on: August 19, 2014, 11:45:58 PM »
Tried a cell phone charger and it worked fine on the solyndra tube.  Voltage sagged to 60 or so IIRC. Iwent ahead and got 11 more. Im planning on putting them in a star or wheel pattern. Im thinking two copper tubing circles, one large and one small with the tubes in between. I'm going to use the.array to power a pump in a pond/water feature in my garden.

Jonathan

boB

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Re: Solyndra PV tube, what to do with it?
« Reply #17 on: August 20, 2014, 03:47:39 AM »

I would just hang on to the tube and use it as a conversation piece to show how dumb our politicians can be some times.

Who knows ?  It might be worth something some day !

boB


Ungrounded Lightning Rod

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Re: Solyndra PV tube, what to do with it?
« Reply #18 on: September 01, 2014, 12:00:28 AM »
Had to look those up, never looked at the technology, just the fact that it was a failed company due to Chinese competition. Interesting idea...

My townhouse is just a few miles from the Solyndra site.  I got to watch it being built, attend a dog-and-pony show and plant tour a month or so before they got raided (and pick the techies brains B-) ), and watch it get shut down, stripped down, and the super-clean "toxic site" bought by Seagate and rebuilt into a new disk drive plant.

The technology was great:  a glass tube, with amorphous solar cells fabricated on the outside surface.  A bunch of them in series (several per inch), so the current and resistive losses are low.  Inside another glass tube with the space between them filled with a non-toxic protective coolant liquid, to displace water and oxygen, avoid hot spots, match the index of refraction so they don't lose light, and to some extent strengthen the tube.  Fabrication nearly totally automated - to the point that things were moved from storage to the line, from machine to machine, and from last machine to finished product storage by slow-moving autonomous robots (quietly playing cute tunes like "grandfather's clock", to warn pedestrians, and stopping before bumping into them).

Assemblies were built by plugging a bunch of tubes into sockets on two insulated support/bus bar devices to make something that looked like a ladder, with the space between the tubes about the same width as the tubes themselves.  Each "Side rail" had a pigtail with a connector at each end - to string them together in a "ladder" the width of an industrial roof.

The tubes convert light striking them from any direction, so you don't have to track the sun.  Just set them up on racks horizontally.  Paint the roof under them white:  The "ladder steps" are spaced out far enough that up to half the light passes between them, bounces diffusely off the roof, and lights the underside of the tubes, too.

The tubes have very little wind resistance.  So instead of a strong, heavy, structure anchoring a giant "sail" of solar panels to the building frame, you just sit the panel racks down on the roof and they stay there.

But the business side was a disaster:  The thing was run by the guy who was a contribution "bundler"" for the Obama campaign.  They spent money like water, to the tune of half a billion dollars.  (How the HELL do you make that back in a competitive industry?)  Bought (or leased?) acres of ground in silicon valley (talk about pricey!) and built a giant factory from scratch.  Ran the construction 24/7 with giant lights and enormous overtime.  Put in fancy landscaping and a LOT of lights.  Fancy architecture, too, rather than a simple, rectangular building.

To get people to adopt a new technology, when an existing one does the job, you need a substantial price-performance improvement to overcome the greater perceived risk of failure or hidden cost overruns.  Rule of thum is that, to actually displace and obsolete the one that you're displacing, the advantage needs to be about ten-to-one.  But with this enormous capital investment to recover Solyndra was pricing their product a bit higher than existing solar panels (even before the price war started).  This meant they were doomed to fill warehouses, rather than sell and be deployed, right from the start.

Here in the valley, even before they went belly-up, we figured that the whole operation was a scam.  Somebody bought a great (or at least plausible) technology, then used it to siphon money out of the public purse into their own, with no real intention of actually selling the product.

The last round of financing was structured so that the government was on the hook for the bill if (when) they went belly-up, while the investors were paid off.  The executives, meanwhile, got to keep the enormous salaries they'd been paid through the whole operation.

Once they'd gone bankrupt, they COULD have been reorganized and might have been quite profitable.  The plant was about as automated as it gets, requiring almost no labor.  Without the half-billion dollar albatross around their necks the panels might have been able to hit a sweet price point.  But the executives absconded with the records and wiped the computers (which people here believe was to hide where the money went).  Unfortunately they were thorough.  They wiped and/or disconnected and removed the machines that ran the line, too.  Without that information the plant was lobotomized.  Just so much surplus machinery.
« Last Edit: September 01, 2014, 12:09:26 AM by Ungrounded Lightning Rod »

boB

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Re: Solyndra PV tube, what to do with it?
« Reply #19 on: September 01, 2014, 01:15:37 AM »
I think that their solar panels sold for about $5 per watt while regular silicon panels were around $2 per watt.

At that price point, they were doomed to fail without some super marketing plan.