Vitosol Collector Installation and a Question

Constantin

Shoma and I came back from our vacation in India to see the Vitosol 300's in place. They are quite beautiful... I can see why someone would elect to use them for shade outside their home...

The only question I have to date is the discoloration of two tubes. Both of them have a milky white coating on the inside near the top of the tube. Is this perhaps the sign of a breach of the vaccuum? The discoloration is only at the top, the rest of the tube looks just like it's pretty neighbors.

Mark Eatherton1

Doesn't look right Con...

I'm sure Viessmann will replace them for you. Those tubes are actually someone elses, but as usual, Viessmann will back their product to the max.

Welcome to the world of ultimate energy conservation. I know it sounds strange, but when I had my DHW system, it just "felt better" taking a shower in water that was heated by the sun. Can't explain it tho...

Congrats. Looks good. Hope you don't get much hail in your part of the country.

I had a customer approach me about using this type of collector. I reminded him that his home was located in the hail belt. He acknowledged and said "They probably don't stand up to errant golf balls very well either do they..."

Seems his house backed up to a future public golf course.

He went with "latent solar"... GSHP. No problem with golf balls there:-)

ME

Paul Pollets

Broken

The tubes have lost their vacuum and need replacement. It doesn't affect panel operation to replace any tubes at any time. I had several defective tubes (from shipping) on the last install. Each tube took less than 5 minutes to replace.

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Constantin

Hi Mark,

I don't think we'll have any issues getting Viessmann to comp the Thermomax tubes either if they're broken.

I really look forward to getting the house up and running and taking my first solar-heated hot shower! Plus, I don't think I'll worry a great deal about golf balls, whether the type made of rubber or ice... It hails very infrequently around here and the stuff never is that large.

Thanks also for the heads up on the LPCO. Was my model designation close to your extant stock?

Constantin

Yeah, not to worry!

Thanks for the reply Paul! I have a training session in May for the Solar systems, so if we haven't gotten the stuff replaced by then, I'll simply carry the bad tubes down to Warwick and bring new ones with me. It's one way to ensure that the tubes don't get damaged in transit...

I'll carry them in the ski sack, BTW. I wouldn't want to have an implosion make my day even more exciting than it already will be!

Bob Gagnon plumbing and heating

2 questions

can I expect to lose a tube every once in a while, or is that just from shipping. I have 1 bad tube out of 120. Could yo tell me more about the solar class in Warwick. Bob Gagnon

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Constantin

Hi Bob!

To answer your two questions:

I doubt that the failure rate on the Thermomax tubes is very high once they have been properly installed. I would think that shipping is a very big problem when it comes to maintaining a vacuum seal with delicate glass containers. So I would expect a lot of teething issues followed by years of trouble-free use if the tubes are used properly...

Though thermomax and viessmann seem to think that these tubes can stagnate fairly safely, my engineering hat tells me otherwise... Particularly given that Viessmann promotes the use of glycolized closed-loop systems which allegedly have had a history of producing "interesting" byproducts as the glycol gets fried. So, careful supervision seems to be warranted, as best as I can tell.

Not that this is a problem. Some TLC is a small price to pay for free DHW. Besides, how difficult is it to test the pH of the glycol loop?

However, the best approach, IMO, is to prevent the tubes from stagnating in the first place, whether by offering a big thermal dump or by covering/removing them, as you suggested earlier.

To answer your second question, here is the PDF that covers the training schedule in Warwick, RI this year. The next solar class is on May 6. See you there?

Bob Gagnon plumbing and heating

congratulations Con,

The tubes look great, think of the energy you'll save in the years to come. The planet can breathe a little easier now. I think I'll see you in R.I. Two questions, what are you going to do in the advent of a power failure, and what size tank are you hooked up to? Bob

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Brad_3

Hot tubes!

Be careful with tubes that have lost vacuumm, they can be very hot when the sun is shining. I'm curious at what temperature they are supposed to stop transferring heat to the header, anyone know? I guess the internal heat pipe fluid is all gas when it gets hot enough, then no flow or heat transfer.

Constantin

Very Good Questions!

The Vitosols are hooked up to our DWH tank, a Vitocell 300B, IIRC. As for power failures, they're pretty rare around here...

Some people have hooked up solar PV panels to circulate hot water... a pretty good KISS approach... whenever there is sun to heat the tubes, there is sun to run the pump... IF the PV panel is big enough to support a pump on a cloudy day.

Anyway, I look forward to meeting you in May!

Brad_9

PV pumping

I think there has been some doubt about pv pumping evacuated tube collectors. They can get pretty hot even in little sunlight, where the pv and pump combination might not start up and the glycol in the header would degrade from high temperature. Though I still seem to remember reading that they are supposed to stop transferring heat at a certain temperature, I don't know what that temperature is.

The only combination I would consider trying is an elCid pump with an oversize pv panel. But you have to be careful that you don't get a pv panel with too high a voltage. The elCid's are only rated for 20 volts and most pv panels will go over that if it's cold out and there is too little load. Also the number of manufacturers making small pv panels is considerably less than it used to be. There is a shortage of cells and materials to make cells and the manufacturers are concentrating on the larger panel sizes where they have more of a market.

So for now maybe a Tekmar 155, Goldline, or similar controller (or the V. Solartrol at about 5 times the price), and a low power pump like a Taco 003 or Grundfos UP15-10, or Brute on speed 1, would be a better choice for your system.

I can vouch for how well the pv pump combo works with a flat plate collector, there are systems I installed over a decade ago that are still running fine. No sign of glycol degradation after 10 years in service.

Ted_9

Solar Class

Constantin, Bob, I'll see you guys there on May 6th.

PATRIOT HEATING & COOLING, INC.

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Constantin

That's great, Ted!

I look forward to the class, should be fun seeing Jim again. Let's see how much of a hard time I can give him this time. ;-)

As for a PV-powered pump one post up, I think the trick would be to have a battery-backup for the cloudy days. Oversize the panel so that it works 90% of the time, charge the battery, etc. and heat some water inside the hot water tank whenever excess current has to be dumped somewhere. There are plenty of smart solar chargers out which can do this, so why not use them?

Another option is to just install an quality inverter and a deep cycle AGM battery. Then use that setup to get through the dark days when the power is out. Very simple, virtually no maintenance, etc.

Bob Gagnon plumbing and heating

good to have you onboard Ted!

what type inverter. Do you have a make or model number Con? My electrician can't find one. will the inverter automatically kick on when there is a power failure? I lose power here quite often. Thanks for your help, Bob Gagnon

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Constantin

Well, yes and no.

I was under the impression that the pump you were referring to was a DC-powered pump (hence it's ability to interface directly with a PV system, right?). Thus, all you actually need is not an inverter, but a charger (sorry, it's late and I have been working on the computer all day).

Said charger will provide power to the battery and the circulation pump whenever the grid is up. When the grid fails, the charger shuts down and the battery provides the necessary power for the pump to be happy. Here are some things you need to consider though:

1. What is the amp draw of the pump?
2. How long are the usual power outages? Hours, days?
3. Do you desire a maintenance-free system?

The larger the pump or the longer the runtime you're trying to achieve, the bigger the battery needs to be. If you don't mind doing some yearly maintenance, I would wager that a bunch of Trojan golf cart batteries (6VDC ea.) would be a very economical way to run the pump during infrequent outages. If outages are quite common or long, then it might make better sense to go with a real deep-cycle battery (the Trojans have thin lead-sections).

The king of the heap for the lazy among us is the Lifeline AGM lead acid battery from Concorde (and they make other models for stationary power as well). Zero maintenance, awesome current capacity, spill-proof container, no venting unless the thing is getting grossly overcharged. It's what I use on Mums boat, 'cause I was sick of having to stock a safey mask, an acid-proof apron, chemical goggles, and arm-long acid-resistant gloves just to safely handle/maintain the old flooded monsters.

I would consider getting in touch with a number of web-sites and reading up on their offerings. For example, I found the stuff at WindSun to be quite helpful. BTW, Windsun sells a 10Amp, temp-compensated charger from Xantrex for about $150. Then there are marine-oriented sites like Jack Rabbitt Marine that also sell solar panels, chargers, controllers, etc. just in case you want to go the other route. However, I would always buy batteries locally, if possible.

If this topic still interest you, perhaps my collection of pages on Battery selection, chraging, etc. might be of interest. I even offer a excel spreadsheet on my site so you can figure out what sized battery you need and which battery is best to do the job. However, as your energy source is the grid, I can already tell you that a cheap deep cycle battery is probably your best bet (economically speaking).

Brad_9

Backup sysetms

Although it's tempting to use a battery backup system with a DC pump, it really takes away from the simplicity of a pv direct ssytem. Then you'd have to have a differential control that runs on 12VDC and I don't think ther are any. I believe the Tekmar and Goldline will run on 24 VDC, but then you're into really obscure pumps, inverters, more batteries, etc. If you're going to add that complexity you might as well use the much less expensive AC pump and controls, and an inverter, there are good ones around.

Inverters range from tiny crap to big or bigger high quality stuff. You can spend $10k on an Outback (www.outbackpower.com) 14kW inverter system ($2k for a single 2kW Outback inverter without any of the safety (breakers and/or fuses) or support parts). The other end of the spectrum is the auto parts and dept. store inverters that will probably fail as soon as you put a pump on it, or soon thereafter. For a backup solar hot water system consisting of a pump and diff control you would want a 300 watt or larger inverter. Though 150 watts looks big enough on paper, upsizing to 300 watts is a good idea to make sure that it can handle the startup surge from the pump. Good ones include Exeltech and Samlex which are both sine-wave output for best efficiency running a motor. These small inverters do not include a battery charger from gid power like the big ones do, so you have to have a charger also. Samlex, Iota, and Xantrex all make good chargers. Look up solar dealers on the web for sources, there are lots of them, it's a much more open market than plumbing/heating supplies. Also check out advertisers in Home Power mag, also on-line at www.homepower.com

Sizing the battery - If running a pump for 10 hours per day (assuming the power goes out while the sun is shining), and the pump draws 60 watts and the control 10 watts running 24 hours per day, that totals 840 watthours per day (60w x 10hr) + (10w x 24hr) = 840whr. Small inverters can be considered to be about 80% efficient, so divide 840whr by 0.8 to get 1050whr of energy needed per day. To get units that batteries are measured in, ie: Amphours, divide the whr by voltage, 1050whr/12v = 87.5ahr. Reserve amps and cold cranking amps are not useable measures for this use, you may have to ask about amphour capacity, and if you can't get it, you can assume it's not the correct battery for the use. With most batteries you don't want to discharge more than 80% of their capacity, so divide by 0.8 again to get 109 ahr needed. This is about what you would get from a group 31 battery. For a backup system with occasional use a true deep cycle battery, like a golf car battery, is probably not as desireable as a sealed AGM or gel battery, you won't be cycling it daily one hopes. The Concorde that Constantine mentioned is an excellect battery, also ones manufactured by East Penn (sold under MK, Deka, and many other names) are top notch. The East Penn gels are actually made so that 100% discharge won't kill them like other batteries so you can use 100% in your calculation.

Hope this helps.

Bob Morrison_3

Looks Great and a question (Bob M)

Constantin,

The collectors do look great.

How much benefit (annual cost savings) are you expecting from them? Why didn't you install PV (or did you do so elsewhere?) This installation was costly: is it the best choice of investment for your energy savings dollars? For example, would have additional foundation insulation have been a better investment? Or, was this not a consideration and you simply wanted these (admittedly lovely) beasts?

Thanks

Bob

Ed Nordstrom

Vitosol Tubes

Constantin, your picture tells me that you need two replacement tubes. Have they been ordered? We will be happy to send them, but we do not want to double up by going outside the normal distribution channel.

Constantin

Thanks for the reply, Ed!

Apparently, the tubes ahave already been ordered. After I posted these pics, I finally I met my HVAC sub when he came in to discuss AC options, and he told me that the tubes arrived in that condition, etc. So, all is well.

I simply didn't want to bother my installer w/these tubes unless I was sure there was a problem... he has a lot of work on his hands and I don't want to be a HO crying wolf all the time (though the LWCO saga probably has the guy shaking his head already).

More than anything else, I'm very much looking forward to finally getting this system going and to take the solar class come May. Also, I can't thank you enough for the time and commitment of your employees and installers to make your customers happy.