Solar panel efficency

Are you restricted in the available real estate on which to put your collector(s)? Are you concerned about the cost to place them in orbit? If not then you may want to consider the $/watt efficiency instead. Or not. Art

Big projects seem to lean toward concentrating a bunch of light on a Stirling engine.

Oh, something like multijunction single-crystal GaAs or InS probably, but unless you've got a NASA level budget you probably can't afford them.

The usual efficiency criteria for ground-based applications is $/peak watt.

Best regards, Spehro Pefhany

Monocrystalline , well established reliability.

Your survey was insufficient, are you into management?

I found this with out trying hard...

I expected to find more at

Cheers

And I _still_ think that the criteria should be the net energy return over the whole lifetime of the product -- mean _after_ you take into consideration the entire extract/manufacture/install/dispose cycle of the panel into account, _including_ the trees you'll need to chop down to make room for them and some projections of the proportion of panels that will be retired early due to defects, obsolescence, vandalism, remodeling, and just plain accident.

Because I think that in principal the whole idea of renewable energy is a Really Good Thing, but it seems to be in the hands of a bunch of poly-anna ditzle-brains who turn off all thought processes when confronted by anything "green", and who are opposed by a bunch of mean-spirited ditzle-brains who let their thought processes get turned off by bibles long ago.

Agreed. These folks, IMHO, really *blew* a perfect "market opportunity". :< Seems like a 10KW stirling engine turning a genset would be *perfect* for a large portion of the population (sun belt) -- especially considering the cooling load they can carry!

collector(s)?

No real estate restrictions but do not need much panel area to light a small room. Orbit? Are you nuts? Do you have an an answer to the posed question?

Not a "big" project in that sense, more like a large number of small projects each needing less than 100W.

So i need to re-ask and base on $/peak watt (not $/watt?). So, of the 5 found, which is the most efficient?

Well, absolutely NO energy source is renewable; the sun is in a downward nuclear fission / fusion path leading to iron. What i looked for was an energy source that did not require energy rich carbon sources (trees, oil); the other alternative would be foot powered generators.

Did i say i used google? Did i give the terms? Thanks for the longwinded PDF.

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I've always been fond of the SEGS family of concentrating solar arrays, 30 to 80 MW each, in the California Mojave Desert. They focus sunlight onto a hydrocarbon heat transfer fluid, heating it to between

Is this for a third-world project? 100W, huh? No cost constraints? Remember, the most efficient technology won't come cheap. What's wrong with charcoal? Trees are plenty cheap.

Have you looked into organic solar cells?

Michael

Also don't forget solar cooling without compressors, minimal electricity required for that. Turn back the technology a bit, not everything has to be electric.

Grant.

BP datasheets for a popular brand is online at : http://87.117.252.3//images/downloads/2602.pdf

You do the figures but it is about 12.5% efficient and $8/W. If you choose the most cost effective you get something more like 8% efficient. Unless space is at a premium price performance wins.

You have missed out Spire who claimed in a press release last year to have a III-V solar cell for a Concentrator PV system with 42% efficiency and awarded a DOE NREL contract to develop it. The figure seems suspiciously high to me but I expect the press release has been garbled somewhat in the journalists brain.

I suspect it is "efficiency" in some PR mans fictitious measure rather than in true engineering terms.

Most other options for flat plate PV are in the 10-15% efficiency and unless you are looking at cost no object you actually want $/W as your measure of performance for ground based usage. You pay an incredible premium to get the last couple of percentage points improvement.

Cheapest improvement with basic flat plate PV provided you have the space and engineering skill is by adding a couple of mirrors as concentrators and improved heatsinking of the PV array.

If Spire are telling the truth then yes. But I expect anything more than

Regards, Martin Brown

On a sunny day (Sun, 30 May 2010 21:03:16 -0700) it happened Robert Baer wrote in :

Well, oil is free these days, just take a bucket and help the clean-up. And if you are a veggy then feet powered generators bikes0 are fed by your eating vegetables. So there really is no problem.

collector(s)?

He might have had an answer, but I predict he won't remember it now...

I'd just open the curtains myself.

It's a reasonable question. Solar panels are frequently sent into orbit.

Sylvia.

Yes, but I find that solar panels don't work too well then anyway.

Sylvia.