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Also by Oz....
Chainsaw Blades!
Forum member Oztules shows us
how he made his windmill blades
with a chainsaw.
Oz's EV
A wind powered car built by Oztules
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| Make your own Solar Panels! |
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 Back to Page 4.
Lets not loose sight of what we are trying to achieve..... we want power and we want it cheap. If we have to buy too much exotic stuff, we may as well by commercial panels as the cost spirals away very quickly.
The output difference will have more to do with the quality of your cells (when you sort them out) than the quality of the glass substrate. My tests showed that a 10-15% loss would result in using normal window glass... Now if one is free (say window for instance) and available, then it beats the bonox out of buying glass that may give you less improvement than buying and sorting the cells properly.
If you bang the cells in without sorting you may degrade performance of a panel by more than 30%....... and waste the better iron free glass.
So, even without the iron free glass, we can make panels within 10-15% of a commercial variant, and there will probably be a no-cost component for the window glass. With the money not spent on exotic glass we can probably build another panel, and have 170% more power for the same money.... even using very ordinary glass......
Glass thickness is also a factor with transmission loss, and the thicker the glass the worse things get..... but again this needs to be balanced out with advantages of strength and availability. The latter is the killer over here. It is just our Government in their wisdom are virtually paying folks to ditch their solar hot water for the new complex heat pump things . So there are lots of 25 year old panels (and younger too) just there for the taking....with the aluminum back as well.
It is of course up to you as to your final cost per watt... but this can be can be very low if you don't try to use all perfect stuff....
Waffle and some more pictures of panels:
As I had the meter out, I decided to check the latest panel again for short circuit current ....
Just to make sure the meter was pretty close to right I used 2 amp meters in series as a rough cross check.
There was a difference, but not enough to excite me unnecessarily...... here they are: |
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They are a bit better than the other day, which was a bit hazy ( big winds seem to get a hazy look to an other wise clear day in the ocean environment)
In this setup. You can see by the shadows, that this was not the noon sun by any means. I did see a few moments of over 9Amps, but this was caused by small clouds near the sun I think. |
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CELLS:
The strangest things happen with new cells. I built a quick and rough cell tester from a 150w flood light etc etc. I sorted the cells, and was disappointed that there were so many less than good ones.... ie 2.0-2.8A cells.... a good amp less than the "normal" 3.8 + ones. Now putting 2A ones in series with 4A ones gives you a 2A panel... bummer... so thats why we test them. We want to see mostly full power panels, and all the duds in a feeble panel.... not mixed.
The odd thing is, when taken outside into the real sun, strange things happen. Most all of the 2A+ cells came up to 3.4-3.9A The really good ones didn't change at all, the reasonable ones improved a bit.......... but the baddies mostly came up to spec or close. There are still some that didn't, and will be made into window glass electric fence panels.....
So now I always test the cells in true sunlight.... twice..... lab conditions does not seem to tell the real story..... I don't understand this at all.
BIGGER CELLS:
For the panels built with the 6x6 cells, and they are fantastic to work with, and perform very very well.
I have seen well over 9A short circuit.
I asked Oz if he could suggest a supplier for the bare cells, below is his reply. Sources may change in time.
http://shop.ebay.com.au/fred480v/m.html?_trksid=p4340.l2562 is the ebay shop for fred480v. He has the best cell deals when he advertises the 6x6 tabbed front and back (short) for 35 cents per watt. This is hard to beat price wise, and ease of use wise. With these 500w/day is easy. With untabbed 6x3 cells, 500w/week is more like it. I haven't tried tabbing 6x6 but assume it is a nightmare for any quantity.
He does not sell the 6x6 tabbed ones all the time, you have to keep checking. When he does, it will be for a limited number, then nothing again. I have bought 3kw of these cells, and are a dream to use, and all full power. As a rule, if they got to tabbing stage, they have been accepted as A grade output by the factory.... but a breakage or tab fault will ruin the entire 19 cell string..... fred gets these... I love em. They come from Shott Ssolar AG in Germany.
Plenty of other places sell good stuff, but not fully tabbed at 35c/watt.. For making big panels, 6x6 are the go, as there is less cells to string for the same power (1/2). In my panels this means only 66 instead of 138 6x3's.
Untabbed cells are a pig in a poke situation. They were never good enough to get tabbed for a host of reasons. Dye color, power out, etc etc. Thats why I would steer clear of untabbed cells, as it is more work, and I have found far less reliable feed stock. I tabbed 1000 3x6 untabbed for 800 useful ones........ the ones I got from mlsolar. mlsolar is a fine fellow, and sells tabbed unsorted ones. If I needed more I would consider these, but still dearer than the 6x6 tabbed ones from fred. (when you can get them).
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