Author Topic: solar tubes (Read 20348 times)

thirteen · « **on:** December 06, 2009, 08:47:29 AM »

Has anyone on this board seen or been around the newer round tubular solar panels? I just caught part of a short program on TV about them. They mentioned that they were used only in larger comercial buildings. I didn't catch there name.

Norm · « **Reply #1 on:** December 06, 2009, 09:21:34 AM »

That would be for heating?

I get confused sometimes between solar panels

for heating and electrical.....

Norm · « **Reply #2 on:** December 06, 2009, 09:28:55 AM »

http://www.ecogeek.org/content/view/2187/83/

how about this?

Simen · « **Reply #3 on:** December 06, 2009, 12:32:53 PM »

Being able to catch and produce electricity from ambient light would mean that these cells have to be the next generation multilayer cells, and wrapping those around a tube would be a waste of area when the sun shines directly on them...

If they're the current gen., they might catch some extra power, but not enough to justify all the extra surface area that are in the shadow most of the time... Although - maybe barely?

My thoughts...

DamonHD · « **Reply #4 on:** December 06, 2009, 01:01:03 PM »

Where they may be good, assuming that the solar area itself is cheap, is where a lot of the radiation is not anything like normal to the roof.

For example, I have west-facing and east-facing roof surfaces and in the winter all the direct sunlight is at a fairly large angle to the normal.

That tubular configuration, especially with a white-painted roof, might catch more of the available light while still keeping the overall structure parallel to the roof for wind-loading and planning reasons. That's why I keep leaning to solar thermal tube collectors.

Rgds

Damon

willib · « **Reply #5 on:** December 06, 2009, 04:23:50 PM »

Just watched their video, good for them.

http://www.solyndra.com/

Since they make their tubes from glass initially, it seems like a no brainer to let the customer use the tube itself to also heat water?

dnix71 · « **Reply #6 on:** December 06, 2009, 07:15:15 PM »

That looks like a winner here in hurricane alley, since they don't need special anchors or ballast for winds below 130mph.

No mention of the $/watt, though. They don't look inexpensive.

zap · « **Reply #7 on:** December 07, 2009, 07:02:57 AM »

It is mentioned here, at the bottom of the page in "comments", that a couple of "decent sized commercial systems" were "$7.1 to $7.4 per Watt" using the Solyndra product.

'Tubes' in a hurricane area would scare me.

The panels efficiency doesn't appear to be too hard to beat compared to other panels, I like willib's idea of incorporating heat gathering which, if implemented, could raise the panels total efficiency.

Here's an interesting spreadsheet of quite a few panel's efficiencies.

http://spreadsheets.google.com/ccc?key=rN3EmdvOo2Lw5bs_fSJ-XxA&hl=en

thirteen · « **Reply #8 on:** December 07, 2009, 08:10:41 AM »

It seems that at first look they will work where you have a large usable area. But for a home back in the sticks in the mountains it might not work yet. I do like the idea of heat and electricity from the same system. I wonder how tough the tubing is. Where my house is real high winds are not that common and usually come with a storm. During the storm some smaller branches are flying off of the trees. I've had a couple hit my solar panels (120 w) and did not cause any major damage. But with tubes it might have. Depends on the support it has. And I wonder about the temp change, because I can go from 20 below to 30 above in a couple of hours. These at this time might be a fair weather item only. I would like to know how they clean them. I'll just have to ask them.

DamonHD · « **Reply #9 on:** December 07, 2009, 09:26:47 AM »

There are combined PV and thermal panels, but they are still rare and expensive, but it gives some hope for combined tubes too.

eg http://www.pvtwins.nl/

Rgds

Damon

TomW · « **Reply #10 on:** December 07, 2009, 09:42:02 AM »

HD;

If their web design is any indication of their manufacturing ability they won't get far.

That may be the suckiest website I have seen in awhile.

Just how I look at stuff I guess.

The basic idea of both types of solar in one unit is a good one, however. IMHO.

Tom

DamonHD · « **Reply #11 on:** December 07, 2009, 11:33:59 AM »

There are others, that was just one I had to hand!

The theory of course being that by cooling the PV with water you actually improve PV output on hot days too...

Rgds

Damon

Ungrounded Lightning Rod · « **Reply #12 on:** December 07, 2009, 02:36:48 PM »

Problem is that if you let it get hot enough to heat the water well it's a bit warm for collecting electricity. Other than that it's a great idea.

thirteen · « **Reply #13 on:** December 07, 2009, 10:46:58 PM »

I contacted them and they informed me that they are biult for commercial buildings only. They are not usable on a steep roof. So for off grid homes it is not available at this time. Thought I would pass this information on.

Volvo farmer · « **Reply #14 on:** December 08, 2009, 03:16:57 AM »

The basic idea of both types of solar in one unit is a good one, however. IMHO.

I'm going to disagree here, but only from a self-reliance standpoint. In one way, this is like those things that have the TV and VCR built together. When one breaks, it makes the whole thing unusable. I wouldn't personally want my hot water and electricity coming out of the same system, just for the sake of not having both systems down at the same time if something goes haywire. It's a moot point anyway, since the thing is not available to us self-reliant types :-)

TomW · « **Reply #15 on:** December 08, 2009, 04:21:32 AM »

VF;

Golly gee. I can't win!

Try to be nice and agreeable and I still get it wrong.

That is it, no more mister nice guy.

Back to my old bad ways for me!

Ha.

Seriously, your point is very valid.

Tom

DamonHD · « **Reply #16 on:** December 08, 2009, 08:09:14 AM »

Depends what you're going to use the water for: if it's for underfloor heating at (say) 30C or pre-heating before your normal boiler then very good. For direct domestic hot water at (say) 60C, less good, so the PV-Twins stuff used to be differentiated into two sorts of collector for those applications.

Rgds

Damon

DamonHD · « **Reply #17 on:** December 08, 2009, 08:18:25 AM »

To turn that around, the PV element could be used to drive the pumps, thus making it a completely self-sufficient system and not subject to (say) power cuts.

If I still do solar thermal, and I'm humming and hawing for a number of reasons, the self-contained nature of such a system would be a good thing in my mind.

Mind you, I already have loads of PV on and off grid, so I should probably quit whining and just use that to power SDHW in a once-in-a-blue-moon grid power cut...

Rgds

Damon

Junkie · « **Reply #18 on:** December 08, 2009, 02:05:59 PM »

Interesting idea, I can't see it being very cheap though ?

willib · « **Reply #19 on:** December 08, 2009, 03:36:28 PM »

This is a blog to sas's 1MW PV Farm.

They have recorded , with graphs , a Midday sag in their PV output.

http://blogs.sas.com/jmp/index.php?/archives/209-Solar-Array-Surprises.html

The strange thing is they say the sag is more pronounced in winter, i'm wondering if the lower part of the sag in winter ,is in line with the lower part of the sag in summer, as far as output is concerned?

Or in summer are the cells already warmed up so to speak, so there is less of a pronounced sag?

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Author Topic: solar tubes (Read 20348 times)