Dawn of a new age???

Mark Eatherton

Anyone install these new Dawn dual output solar collectors? PV and ST in one rack. Looks velly intellestink... <a href="http://www.dawnsolar.com/">www.dawnsolar.com</a> ME

Kevin_in_Denver_2

Nice looking, bad performance

I've been very interested in these for a long time until Damon Villpu gave me a heads up about the collector efficiency.  According to the SRCC report, output drops to ZERO once the temperature difference between ambient and collector inlet exceeds about 20F.  The Y-Intercept of the collector efficiency curve is .126, about 500% worse than the average glazed collector.



That came as a big surprise to me, because the original NREL report (attached) on Roof-Integrated solar absorbers (RISA) indicated that the Y-intercept would be about .55, a respectable number.  I also did some measurements of my own that indicated if you SMACNA- taped PEX to the back of green metal roofing, you could make DHW for 10 months/yr.



So it appears that Dawn Solar dropped the ball when they adapted the NREL design for producibility.  That leaves only one viable hydronic PV/T hybrid available, SunDrum.  The field is still wide open for a  Building Integrated photovoltaic/thermal (BIPV/T) hybrid collector.  Lots of architects and owners want the best looking solar possible, which would be a collector that looks just like standing seam metal roofing.

Kevin_in_Denver_2

BIPV/T Hybrids

This hit my email inbox today--



Just a bit more incentive for the continued development of a good BIPV/T collector:



"Finally, like all venture capitalists, 21Ventures seeks to invest in under-invested sectors. While numerous thin film manufacturing companies are out raising capital, considerably fewer companies in several other promising sectors are emerging. 21Ventures believes sectors such as building integrated photovoltaics (BIPV), concentrated photovoltaics and thermal (CPVT), piezoelectrics, and agricultural technologies are all under-invested segments of the clean-tech industry."

http://21ventures.net/files/21V_newletter_Q42009_10.pdf

Karl_Northwind

dawn solar

There are good applications of Dawn solar in some cases.

we worked on a Dawn solar installation using sunslates, and it's OK.  I can't say much more than that. still too new to know more.

the primary use of the Dawn Solar in a lot of these dual system PV/ ST systems is to remove heat from the PV module, increasing it's efficiency. it's a semi conductor and is more efficient at low temps.



this is also A dawn solar/GSHP integration.  I still need to finish the integration work on it to make everything work smoothly, pre heating the incoming ground loop temps.  we're also going to use the dawn solar to do snowmelt on the PV system.



FYI, for flatplate collectors, if you integrate it with A GSHP system, and put your usable heat production temps in the 40-60F range, your heat output of the collectors doubles.  yep.  doubles.  that's in comparison to a usable range of 80-120 F we usually use for Flatplate collector space heating systems.



peace,

Karl

Kevin_in_Denver_2

w/w Heat pump integration

Karl,



When your solar storage is depleted, does you heat pump system just default to electric resistance?



This was always the achilles heel of that type of system when I used to troubleshoot them in the '80's.   Most people were better off with air to air.

hot_rod

isn't it basically an un-glazed

collector? As such cold weather performance on the thermal side must be minimal. Look at the performance of a pool collector as the ambient drops. It's similar to using a slab of concrete as a collector. It looks expensive to install?



I do like the creativity of the product and it must be a help for the PV collectors. The clean look will have a lot of appeal.



How it pencils out for output on both PV and thermal based against the installed cost will determine how well they sell. Smart consumers want installed cost, and predicted energy cost offsets.



hr

Karl_Northwind

GSHP solar

The way this system will be integrtated, we will be dumping a bit of heat from the solar tank into the incoming water from the ground loops.  VS pumped to just bump up the water temp about 10 degrees from the original incoming temp.  it's just going to raise the COP a bit. in the summer we're going to use the same piping to dump excess heat to the ground when available, disabling it when the AC has to run.  With the dawn solar there is no chance of overheating, we're just liquid cooling the PV in the summer time, and bumping up the Geo COP a bit in the winter time. 



the installed cost of the dawn solar is pretty low per sf, and if you can use really low temps most of the year, it has the ability to produce some usable heat.  In my opinion (and I haven't run the calcs) in a conventional application (non geo) the usable heat would be really minimal for easily half the year in our WI climate.



cheers,

karl

DanHolohan

At AHR

Navian was showing a solar panel that did both ST and PV.

Kevin_in_Denver_2

Sun Drum?

Sun Drum and Dawn solar are the only viable ones I've found.



Did the Navien one look like the attached photo?



http://sundrumsolar.com/index.php/products



The piping inlet/outlets are the 4 holes in the back of a conventional Sanyo type PV panel.   It's called Sun Drum because it's like a 6-sided thin aluminum box that allows the antifreeze fluid to pull heat off the back of the PB panel.

DanHolohan

No.

Go here and scroll to the Navien section of the video. I'll show it to you:



http://simplystreaming.com/simplystreaming/player/player2.php?nL=1&aKey=130

Kevin_in_Denver_2

Roof snowmelt

Dawn solar is perfect for roof and PV snowmelt.  Lower slope roofs in snow country absolutely need this to get the snow off the PV panels.



Check this thread: 

http://www.heatinghelp.com/forum-thread/118410/Radiant-Roof-melt#p1067223

http://www.heatinghelp.com/forum-thread/118410/Radiant-Roof-melt



But again, be careful about the expected solar collection from these.

Kevin_in_Denver_2

Hybrid PV/T solar panels from Navien?

Dan,



Fantastic job on the video. Navien is truly a "game changing" product. Unfortunately, I can't find any information about their hybrid collector, and if they have plans to start selling it in North America.



Your video is the only thing out there that I could find.

DanHolohan

That's my only exposure to it.

Haven't heard a word from them since. 

Tom in Maine

No new age here

The only thing the Dawn system has going for it is the fact you cannot see the collector.

The construction is basically a radiant floor on the roof before the metal roofing goes on.

This is a thermal disaster and the SRCC numbers back that up.



If one does not care about cost or payback, then this is their system.Wonder what happens if there is an abrasion leak on the PEX.

Yikes!



Tom in Maine

Mark Eatherton

What if it were coupled with a super high efficiency transfer method...

Like a water source heat pump capable of generating water temps between 120 and 140 degrees F?



In doing that, a person would also have the distinct advantage of lowering the air condition costs as well, so its a win/win proposition with year round energy savings.



The technology is here today...



Thinking outside the box :-)



ME

Tom in Maine

Maybe

A water source heat pump would certainly help. One has to ask is this all worth the investment. Maybe yes, if it is cooling a PV system. You are keeping the efficiency of the PV's up and perhaps affording them more longevity. Considering the cost, color me skeptical. Many folks seem willing to spend the money without analyzing the cost/benefits very well.