Actually, Nick, this is one of your better ideas. Do you have a graph showing the output vs. light intensity of a solar panel? How much fall-off is there with increased intensity (at similar temps)?
Oddly enough, for my cabin once the snow melts, I'm going to try some kind of cooling solution for my panels. I can't use the lake water because in the summer it's too warm. So (since this is a weekend place) I plan on mounting a 10 or 20 gallon cooler on the pole, drop a bag of ice in it, fill it with lake water and flip a switch. Using a misting system that they use in grocery stores that comes on once in a while for a few minutes might, I repeat might cool the panels enough to increase the power. My question for my self right now is do I mist the bottom and keep the top clean or plan on using windex every week on them?
See, during the week nobody's there, so I don't care if the panels are going full speed. Just keep the batteries topped off for the nightlights and such. During the weekend I want to run the T.V., computer and crap so increasing the potential of the panels even a few % might be worth the effort. I already know having them on the shore of the lake will increase the power from them.
For all that trouble you might get a 2-3% increase at max, and risk causing a lot of extra corrosion and mineral buildup on the panels. And if you have to clean them off with a scrub brush every week you will cause scratches in the glass, which will further deteriorate your power.
------------------------------------------------------------------------- Free Solar Discussion Forum:
ROFLMAO
You, claiming one of the most respected solar dealers in the US knows nothing about PV! What a laugh. No one here even believes you own a pv panel ....
If you had a solar panel, and if it gained 25% by cooling with water, that would mean it's running above temp spec, and you installed it incorrectly. They need to have airflow under them.
-- Steve Spence Dir., Green Trust, http://www.green-trust.org Contributing Editor, http://www.off-grid.net http://www.rebelwolf.com/essn.html
On the ICP thin film, it had 12" x 12" of glass on the front and back which got rid of the heat nicely. I had 2 square feet of sun area with the reflectors and the glass got to about 160F on a 90F day. If I had made the reflectors out of aluminum and used them as a heat sink, it would have brought the tempature down. Seems like if you have the same area for heat sinking as the sun area , you should not have a heat problem. I could have put a 1 square foot aluminum plate on the back glass with cooling tubes through it to run water, that way I would have gotten electricity and warm water. If you search "PVT+solar" you will find many similar PV and solar thermal designs.
Harry Chickpea asks for:
IIRC, that's linear, or slightly better. The 25 C panel IV curves at
show max power (the peak of the concave-down curves) at 170 W and 1 kW/m^2 and about 95 W at 600 W/m^2, and 95xlkW/600 = 158 < 170 W, so it looks like doubling intensity more than doubles power, up to a point. Rich Komp suggests
2-3 suns are OK, if panels are cooled to 50-60 C. Above that, there could be problems, eg I^2R loss or metal migration. Sharp's 208 W panel produces about 118 W at 600 W/m^2, and 118x1kW/600 = 197 W.Wasting heat from a PV system to increase the output might make economic sense, but thermal systems are still far cheaper per peak watt. Adding PVs to a draindown thermal system like this increases the payback time, unless they are heavily subsidized.
Nick
We were thinking of different systems, I was thinking you were putting the panels right in the water and concetrate aggressively. Deionised would aviod conduction and deposits on the panels.
With your system you'd still need to avoid scale and muck buildup, so I'd still want to deionise for a maintenance free system. The necessary deioniser feed rate would be tiny.
avoid cold spots.
FWIW greenhouse poly doesnt have anything like the necessary life.
how hard can standard panels go with water cooling?
If you want to separate panels from water, surely it would be better to put your film-contained water under the panel, where it doesnt kill light throughput when it gets dirty, and where the heat absorbing side is in much closer contact with the water. Then you probably dont need to descale or deionise.
NT
often errs but seldom doubts:
That invites corrosion.
Not required for a tiny amount of makeup water, IMO.
Bullshit :-)
Surely not.
Nick
should be ok for 20 years.
hardly. You might be happy to make systems with parts that need replacing every 4 years, but this is not at all a good option in the marketplace, where such failures will earn the product a bad reputation, and add considerably to ongoing costs, due to householders bringing 'a man' in for any little thing. If you want these designs to succeed on anything more than an experimental scale they need to use materials that last 20 years or more. If youre just experimenting, poly would last a few years, if it escaped any damage.
Why would you rather have the cooling on top? Water loss thru the poly? That could be addressed with a coating on the panels, and cooling underneath may allow more concentration.
NT
You think his comments need clarification? OK, I'll help you out:
YOU'RE AN IDIOT
Wayne
One thing to consider, if you did not use water, just thermally conductive reflectors as heat sinks, is wind. This is not small factor. If you tried to take a panel that measures 2' x 4.5' and put refectors on it, the reflectors could stand up a foot or more, if you wanted any significant gain. We get some
40 mpg winds here and I would not want to try withstanding those.
that you, SolarFart, are so full of BS, it has turned your EYES BROWN.......
Me
wmbjk , got a giggle withh:
G'day Wayne ('n the rest of the Crew), After a very pleasant sojourn in the Great Southern Ocean, I return for 2006 - with pleasure :-) Most warming to see the GymmyBob//bengi//SolarF'UP goon is reaping his just rewards
To answer a query I read, Re: "Why does GymmyBoB do fups to ?? Its something I am able to say I have to confess to
*iT* learnt that "strategy" from myself. Of course he missed entirely the reason for the action in setting fups that way, and it has nothing to do with this NG, believe. Whilst he does not understand, it is good. Educating this particular arsehole is dangerous to *any* NG AnD. To update you on another thread:#Newsgroups: alt.solar.photovoltaic #Subject: Re: SunBall Solar Appliance kWhs at less than grid costs #Date: 3 Nov 2005 16:21:41 -0800 #Organization:
I did not make it to Adelaide to meet Greg, after the scheduled run around Tassie, somehow we ended up in the Whitsundays instead - it was cooler there than Latitude 34° 50'S and no risk of smokehaze (forest fires) However I did catch a snippet on the local news that waffled on about our Fed. Govt. again dumping on the Solar Industry here, with a proposed removal of subsidies. Greg had something to say about that action jeopardizing his new business..or some such. Whilst he is dead right, and yes it is (and always has been) a significant part of industry growth here, Greg I fear is discovering more of what I (and others) said in the thread (above) about the path from invention to sales to profit. The page is still up so I 'assume' all remains well with Greg's venture.I guess like many others before him he will simply have to "live with it", in relation to subsidised sales.
All the best for 2006..an keep with the good work in getting only good info out :-)
cheers
Ln
Actually it would be 2' high for each of 2 reflectors wings. One on each side for a concentration of 2X. It would be at an angle of 63.4 degrees.
You should. The national building codes suggests, maybe require, the structure resist a wind load of 10 lbs per square foot. This is about 90 mph.
Duane
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