Maximum delivery for a solar panel????

Ed_26

I would think with 4 panels, 1" would be proper. For drainback I would use panels w/1" headers & 5/8" od risers. Note that I am not yet certified for solar installs/design. That said.. I have done a lot of study & research over the past year, preparing for my own system. 3/4" pipe could work, properly graded, but 1" would be better IMHO.

Mark Hunt

I hafta ask


I am working on a sloar home just now and I was talking with the "solar dude" that is supposed to supply the family with HW with his panels.

Well......he tells me that under "optimal" conditions, he can deliver 30k btu's/day. NOT per hour,,,,PER DAY. A 6 hour day. 5k btus/hr.

Is this all you can expect?? Or is this guy using frosted glass panels?

Gotta' tell ya'.............. the HO is going to be VERY unhappy if the solar panels don't do what he thought they would.

Not official yet but, upstate NY is not a "solar efficient" area.



Mark H

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Ed_26

solar panels

Depends on insolation, tilt etc. I would say thats close... without more info - who's to know? For my location, optimum is 317 btu/sq.ft. per day. the rest is math...

Mark Hunt

Thanks Ed


The home was built for max solar exposure as there are PV panels as well.

Solar dude told me that the panels were angled for max winter performance and there are four of them measuring 4' x 8'. That works out to 128 square feet of panel. By your numbers that would be 40,576 btu's/day.

Guess I was just expecting more.

Mark H

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ScottMP

So was I Mark

After seeing so many panels at ISH and having customer starting to show interest, I was looking at output also.

Combining what I have been told and ME's experience from another thread, this will be a tough sell. Payback in my opinion IS NOT going to be a sales tool. The desire for solar will need to be Very Green if we are to install these systems.

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Mark Hunt

That's


the conclusion that I have come to. Are these panels REALLY the answer to our energy needs? I just don't see it now. I never really paid close attention to solar heating before this job and I just assumed that the panels grabbed more energy than they apparently do. My bad.

Another side to this is the storage tank being used on this job. It is nothing more than an electric water heater with a couple extra taps. The insulation is no different than a standard electric WH. What are the stand-by losses?

To be fair, the solar dude is using a drain back system so that he can keep his glycol mixture to a minimum for max energy transmission. If this home had five people in it, I do not see how the solar would ever keep up. You would need a heck of a lot more panels and a HUGE amount of storage. Even then, a back-up system will need to be in place.

Looks like my Prestige Solo will be called upon more often than I thought for DHW production.

Mark H





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hr

SDHW makes a lot of sense

as far as a payback. You should be able to handle 60- 70% of your DHW load with a two panel and 80 gallon preheat tank. Perhaps in the 8 grand or under price range.

Around here I tell folks to figure on a 30% heat load from the solar. But you can easily drop 20 grand into an 8 panel system with 5- 800 gallons of storage, controls, etc.

Passive solar makes the best use of solar energy, for heating

www.pmengineer.com July 2006 has a good "Sunny Side of Hydronics" article that Siggy wrote.

Also Aug and Sept 2004 in www.pmmag.com "Seasons in the Sun" and "Sunnyside Up" show some more solar, based around systems in upstate NY, I'll bet.

hot rod

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ScottMP

HR

Do you agree with the output numbers per panel ??

Scott

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jp_2

depends

it depends on location, not so much the panel.

below is expected outputs for st. louis area

Jamie Hall

It is possible

to design a house -- from the ground up -- for 100% passive solar heating in New England; my father-in-law, who passed away recently, did that for a living.

However. That said, it is not easy. It is passive. It does NOT use solar panels on the roof. And it does cost about 10% more than conventional construction.

jp_2

that I'd like to see

I find that a little hard to believe?

on a $200,000 house, that only $20,000, so without a heating system, passive solar would pay for itself before the people move in???

i do agree passive is the way to go, up here we need a artifical boost of heat though.

Ed_26

solar

I also see it's a drainback system - why glycol? From my research, glycol in a drainback system poses two problems.. pure water is the best HTF, & glycol will not completely drain out, leaves droplets in the headers & risers... under stagnation conditions,(drained) the hot panel will evaporate the glycol, causing it to deteriorate & turn acidic, damaging the piping. (corrosive) Comments?

Mark Hunt

Makes sense to me Ed


but I think the reason the solar dude adds glyc is because he is afraid that the system will not completely drain back.

Mark H

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Ed_26

drainback

Huh! All he has to do is fill the system, mark the htf level, run it, mark the htf level, shut it off & see that it 'drains back' to first level??? If panels & piping are properly installed & sized, it's a no-brainer.

Mark Hunt

Ed


"If panels & piping are properly installed & sized, it's a no-brainer."

Now see..........there's the catch.

He tries......but.......uhhhhh.........you know.

BTW, he has piped to all 4 panels with 3/4" pipe. I would have thought bigger, say..... 1"?

Mark H

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