DIY lecky

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evelyn
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DIY lecky

Post: # 143865Post evelyn
Mon Feb 23, 2009 8:12 pm

I have been looking in to solar power lately, is it something i can DIY?
And where can i get free downloadable information that will not blow me up?

There is loads of stuff available but it is ££££ and i dont have any of them spair.

Any of you built a solar panal? dose it work? how hard was it?

Eve

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Re: DIY lecky

Post: # 143871Post Clara
Mon Feb 23, 2009 8:38 pm

Hmmm well you see google ads for diy solar pv around, but TBH you have to wonder how DIY it can get, afterall you are not going to be able to make the cells themselves as that's pretty hi-tech, so you'd have to buy them.

Another thing I would wonder is how efficient DIY could be. You live Manchester, not exactly renowned for it's sunlight hours!

On the positive side DIY solar hot water is infinitely more doable (though I reckon you'd still only be able to work it as a pre-heat for your boiler), there's lots of info available on that (probably something n the main ish site). And how about building yourself a solar cooker?
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Re: DIY lecky

Post: # 143890Post frozenthunderbolt
Tue Feb 24, 2009 12:52 am

2nded. Lots of DIY/scavenged materials designs for passive and active solar hot water systems out there - use google. If you grow your own then a solar food dryer may be worth investment. my feeling is that you need either significant sunlight or REALY significant collector to compensate for average sunlight to make a solar cooker very effective.

This said there are several on here who are far more qualified than me to comment on all this. :cheers:
Jeremy Daniel Meadows. (Jed).

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Re: DIY lecky

Post: # 143899Post Clara
Tue Feb 24, 2009 7:55 am

frozenthunderbolt wrote: my feeling is that you need either significant sunlight or REALY significant collector to compensate for average sunlight to make a solar cooker very effective.
I have to admit that I bought mine rather than made it,though it paid for itself in terms of reduced gas use during the first summer. Probably a different matter in the UK though, as I find you really need uninterrupted sun to get it to 200*C.
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Re: DIY lecky

Post: # 144202Post dave45
Thu Feb 26, 2009 8:34 pm

evelyn wrote:I have been looking in to solar power lately, is it something i can DIY?
Any of you built a solar panal? dose it work? how hard was it?
Eve
Yes I have built my own 36-cell (crystalline) solar panel. And it worked/works

I bought broken solar cells mail-order from the USA. First mistake - for the effort involved it would have been better to buy perfect ones! but broken cells were cheaper... They have to be electrically measured, and matched - in a string of 36 cells your maximum current is determined by the weakest single cell. Each cell is around 0.5 volts open-circuit times 36 - gives you (just under) 18v with no load. You have to solder copper tape on to each cell... not easy, even with special solder. And you will break some cells. I think my broken cells had weaknesses!. Then you have to fix each cell to a flat base, and connect it in series to the next one. I used a thin plywood base and silicone bath sealant. This may or may not be another mistake. What was certainly a mistake was testing it all outside (thats where the sun was!) before sticking them down. A gust of wind picked them up like a string of tiny silicon butterfiles and smashed another 20% of them :-( The cells themselves are very brittle like thin card made of glass. They crack like glass. In full sun this array should/would/did deliver about 2.2 amps (on 12-14v battery-charging duty thats a 25 watt panel. Or a 36 watt panel if you are comparing with commercial ones)

My idea was to slide the cells-on-plywood between the panes of an old double-glazed window I had spare. I gouged the aluminium separator off one end and scraped out all the black gunk. It was a @@@ of a job getting the assembly to fit between the panes, but I did it. I was reasonably solid too. I planned on sealing it back up after I'd tested it.

So one bright day in September (!) I left it propped up against the shed charging a 12v battery. I came back after an hour or so to see how it was getting on. Utter disaster. The heat (!) had melted all the black gunk around the other 3 sides of the DG unit, and the whole thing had fallen apart, damaging yet more cells.

And there it has stayed ever since. I have yet to come up with a decent way to mount the home-made array that is weather proof. I only had that one DG unit the right size and I've broken it. For the time and effort and heartache involved I vowed not to do it again and buy some commercial panels. I did (off a guy on ebay) - the craftsmanship is excellent, the whole unit is light and strong and there is no chance of accidentally busting the cells.

Even with commercial panels, you have the problem of mounting them. I wanted a light and strong frame to mount on my garage roof. Where DO you get aluminium sections from? None of the B+Q type places will do them. I had to buy from manufacturers via a friend of a friend's contact in a truck body shop. Riveted it all together, screwed in the panels, wired them up and fitted it to my garage roof. Not very well - it now leaks in heavy rain). And it has been there for 5 years. The panels have been faultless. But just about everything else has gone wrong.

I used to think 12v wiring was easy and safe.... WRONG.. these panels could belt out 15 to 18 amps in midsummer and the wiring overheated (imperfect connectors) and nearly burnt down my garage. I charge an array of 4 large (110Ah) leisure batteries via a charge-controller .. but I've killed two of those by overcharging (you need to top up their water religiously in summer when they charge at high currents).

My smart Trace/Xantrex inverter has recently died. Anyone know how to fix them?

I also have a Marlec wind turbine and I did experiment with amorphous solar cells (again coz they were cheap). I wouldn't recommend either.

Commercial panels every time. Even in Lancashire sun is far better than wind. In Spain or Greece my setup would doubtless deliver 2 or 3 times as much energy as Lancashire. But the panels do work... they are just far too expensive.

I do have some more cells, and another DG unit now.... mmm what should I do ?

evelyn
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Re: DIY lecky

Post: # 144239Post evelyn
Fri Feb 27, 2009 7:25 am

Thanks for that Dave, Very helpfull but rather disapointing.

I think i will give this project much more thought, i will either end up having them installed and built by a pro or be put off by the cost and thinking about it for ever more.

Eve

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Re: DIY lecky

Post: # 144429Post Wombat
Fri Feb 27, 2009 10:42 pm

Interesting Story Dave!

While I used commercial panels, I did the rest myself and it has been an evolving project over the last 25 or so years. The story is in my article section on the main part of the site if you want to have a look (and it saves me retyping it all here! :mrgreen: )

Nev
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Re: DIY lecky

Post: # 144447Post The Riff-Raff Element
Sat Feb 28, 2009 7:24 am

Very interesting tale Dave!

Evelyn, one the plus side, although you might not enjoy the most intense sunshine in Manchester the forward march of technology is on your side! And during the summer months you do enjoy more daylight hours than those of us in lower lattitudes.

Notwithstanding, I think I would be more inclined to look at water heating to save money. The new evacuated tube technology is astoundingly efficient and gives quite passable results, I am told, even on cold, overcast, days.

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Re: DIY lecky

Post: # 144454Post Clara
Sat Feb 28, 2009 10:09 am

Vacuum tubes are so much more efficient in terms of bang for your buck - put it this way I paid 6 times as much for a PV system than I did for my water system, though obviously you cannot compare them like for like I would say that we get the same "quality of life" from both systems.

After installing solar hot water and getting a solar cooker we went from using a bottle of gas every 3 or 4 weeks to one every 3 or 4 months, at the very least that's a 75% reduction!
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Re: DIY lecky

Post: # 144565Post dave45
Sun Mar 01, 2009 12:41 am

interesting that all the encouragement comes from outside the UK innit?

:-)

evelyn
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Re: DIY lecky

Post: # 144577Post evelyn
Sun Mar 01, 2009 9:02 am

Maybe Brits just understand there limitations :lol: and the limitations thrust upon us by the climet :lol:

I have decided to put solar energy on the back boiler for now and concidder underground water heating insted so if any of you have any experence with this system good or bad let me know.

Thanks for all your valuble input, it is good to aspire to free energy but better to find something that works :flower:

Eve

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Re: DIY lecky

Post: # 144579Post mamos
Sun Mar 01, 2009 9:11 am

Fantastic post Dave

It is good to hear from somebody who has actually tried to build a panel.

It is something I have been thinking about myself

I found this website quite interesting although he does make it sound a bit easier than it probably is as Dave can testify.

http://www.mdpub.com/SolarPanel/index.html

Good luck

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Re: DIY lecky

Post: # 144599Post dave45
Sun Mar 01, 2009 2:43 pm

mmm your link doesn't work at the moment

is anyone interested in the pics of my solar cells experiment? I'm sure I have them somewhere :-)

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Re: DIY lecky

Post: # 144616Post evelyn
Sun Mar 01, 2009 5:30 pm

dave45 wrote:
is anyone interested in the pics of my solar cells experiment? I'm sure I have them somewhere :-)
Absolutly!

Eve

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Re: DIY lecky

Post: # 144968Post dave45
Tue Mar 03, 2009 10:38 pm

Image

Step 1 - check which arrangement of cells is best... we will need 36 cells at 0.5volts each to give 18volts. Yes 18 not 12. Whatever charges batteries has to be at a higher voltage than the battery, AND to overcome the voltage drop of any diodes/rectifiers that may be used. So we need 36. That could be 6x6, 9x4, 12x3 etc Look around - you will see these arrangements in commercial panels. Most popular is 9x4 and thats what I went for.


Image
So thats 36 cells to be wired in series. The cell supplier recommended and supplied electrically conductive tape, adhesive on one side. The front side of one cell needs to be connected to the back of the next, which requires a twist in the tape which is difficult to make neatly. I also couldn't believe that sticky tape would be good enough to carry the huge current on its own, so I needed to solder the non-sticky side to the cell via a blob of solder. On some cells the solder just wouldn't stick. Even after cleaning with isopropyl alcohol and very fine wet-and-dry paper. Some soldered pretty quick... Others took a lot of swearing and up to 30 or 40 minutes ! On average say 15 minutes per connection. Times 36. thats 9 hours. Plus repairs when you break things. Note the green implement for rubbing down the sticky tape !


Image
Real kitchen table stuff this !... great until you have to clear it off for mealtimes... Those cells are fragile. You can see how this will take shape. I think I got 50 cells to account for breakages... you can probably see how some have greater area than others... the smallest/weakest cell determines the max output of the whole series array... These were the best matched cells. That was before they got damaged. Once connected I subjected each cell to a standard test - I measured the short-circuit current produced by a 60watt table lamp 6 inches above it... this gave a full-power output of 2-point-something amps which I wrote down on the plywood next to each cell. One cell was utterly dead despite looking perfect. Good job I tested them, coz that killed the whole array. and used up another spare.

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