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Solar Hot Water system (1 Viewer)

Jay H

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In my ever looming home purchase, I'm considering taking my first step into green-ness by putting in a Solar DHW (domestic hot water) system. I'd love to go full electric via solar panels but it's too expensive for me at this moment and as my house is gas, isn't as cost effective, but somewhere down the line, would love to install a solar collector, inverters and some kind of switch for regular home use and only use the grid as backup.

Anyway, back on subject, has anybody here have any XP in Solar DHW, which I think is a good first step for me? I have a fairly new gas basic 40g water heater in the house I am about to purchase and one of my near-long term goals would be to install a solar heater system. Has anybody done this as a DIY project? I am currently reading up on the two different systems commonly in practice. One uses heat exchanger with glycol connected to a solar panel sized to meet your requirements, and another seems to basically use copper piping to pump water up to the panel and gravity back down to the expansion and storage tank.

If anybody has done this work themselves or bought a kit or even hired an installer, how is it working out? Any problems in winter so far, how much was it, etc?

Thanks,
Jay
 

Hugh Jackes

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I had a system like this one a house that I owned on a Vermont mountaintop. I hired a company to install it; at the time it cost me (if I recall correctly) around $5k, but there was a tax credit in place, since expired, that returned 60% (again, if I recall correctly -- this was 20 years ago). Temperature sensors in the solar panels and the tank fed a thermostat, which turned the glycol pump on whenever the temperature in the panels was 5 degrees or more warmer than the water in the bottom of the tank and off when the temperatures were equalized. The glycol heated the water through a heat exchanger in the bottom of the tank.

I also had the a convection loop from the hot water tank to my wood-burning furnace, so that I continued to make free hot water on cloudy days (of which there are many in Vermont).

Jay, I made so much free hot water, between the sun and the fire, that the water frequently got too hot in the tank and lifted the relief. (The solar system was set to stop making water when the water temp got too hot. The fire loop, on the other hand, was completely passive and kept on working whenever I had a fire, which was 24/7 for 7 months of the year.) I plumbed a loop out of my water tank (120 gallon) to a series of hot water baseboard radiators, to more efficiently heat my house. I still had to place a 20-gallon galvanized steel basin under the relief valve to catch the occasional spur of steaming water.

Sometime in April, I would let the fire go out, until sometime in October or November. In those five months of rough sledding, when the system was solar only, the system never used the electric back-up heater coil.

One drawback that I noticed: Occasionally, when the water in the tank was plenty hot, the glycol pump never turned on and the anti-freeze in the panel loop would get so hot that it would lift the relief on that loop, dumping out the glycol on the roof. I had to have the contractor come back and recharge the loop for me. He never charged me for this service. This could have been a problem caused by my wood loop, though, and wouldn't necessarily be a problem in a totally solar system.

One comment: I said that we had a 120-gallon water tank. At first, this seemed excessive to me, especially since my wife and I were DINKs at the time (Dual Income, No Kids), so there were just the two of us in the house. But, I came to realize that the size of the tank was so that you would have the capacity to tide you over in those (frequent) Vermont periods where the sun didn't shine for days at a time.

If you have any further questions, please do not hesitate to ask.
 

Jay H

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Thanks Hugh, that is awesome info. I don't have a wood stove but am considering one for the long term. Again, my new house is a small 1100sf log-sided ranch. It has a fireplace which I will probably use a lot this winter but a wood stove is something that would be cool. It doesn't need a lot of heat to heat a small place such as that.

I'm currently looking into installers and stuff, but I'm handy enough and very willing to learn to DIY, as much as possible.

NJ has issued a couple clean energy programs with rebates for alternative energy, the rebates are going down next year but it's still worth it, at least for me. I'm told that a solar power conversion would cost anywhere from $8-$12 average per Watt a normal household would use per year.

I'm sure to have more questions, but just gathering info right now...

Jay
 

Philip Hamm

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Do it and tell us all about it. I want to do this in my house but have only read up ont he systems. I recently met with someone who had this kind of setup for 20 years and despite a good experience went to gas when it needed major service. (because the tax incentive wasn't there any more for the solar)
 

Grant B

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I looked into it when I was remodeling/ rebuilding my house a few years back.

States and regions vary widely I believe and when I took a look, PG & E was not very nice.
If I wanted to be on the grid for backup, PG & E charged something like 90% of your normal bill just in case you needed them. At that rate it would have been over 20 years to recoup the costs and then deal with things like battery disposal etc.
I hope you have better luck but make sure you look into it carefully....lots of fine print
 

Jay H

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Yeah, I definitely plan on researching it myself this winter. I think to have a professional install it and what I think they would charge, it would be cost prohibitive compared to the amt of money I would save in my house (which main energy source is gas, as I've mentioned), however, if I can do it myself, it would be something I think might be doable if I can find the panels at the right price. I'm a bit familiar with DC inverters and surely can learn more about ones that are made for home use. What I'm not familiar is with automatic switching devices (such as a UPS backup) that I would use to switch to the grid when say my battery runs low or for major appliances, etc. etc. But I figure there has to be some books out there on installing solar panels and inverters and batteries..

Jay
 

Hugh Jackes

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My sytem was for hot water production only, not affiliated with the electrical grid. The glycol pump was powered off of the household AC, rather than from a dedicated solar panel, as some of the Cadillac systems at the time did.
 

Jay H

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Hugh, sorry, I was diverging with even longer term plans about installing a solar panel system for house electric. Just thinking out loud if it would be something I could do myself.

First step would be the Hot Water heater though....

Jay
 

Marc_Sulinski

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If you want to spend as little money heating your house as possible, I would avoid using a standard fireplace. While the area five feet around your fireplace will be warm, the rest of the house will be cold, as an open chimney is a great way to release the heat from your house.
 

Jay H

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Marc, Agreed, a masonary fireplace with the heat engineered to go through the house before escaping would be the way to go, however, other than keeping the pipes from freezing with the house heat. My small house has one large living room which is basically where I'll be when not eating or sleeping so the fireplace will provide enough for me and my home theater on the cold days I'm not skiing, snowshoeing or winter camping. At least enough for me not to run the gas furnace too much (other than what I mention already). Perhaps I can install a wood stove or so sometime in the future...


BTW, does anybody make/install/engineer a solar heater for a baseboard water heat? Along the same lines as the solar hot water heater, I'm thinking something solar could be worked out for the hot water heater as long as you have a reliable source to keep snow off the PV panels.. right? Does anybody do this? I've only heard about solar hot water heaters. I know the 2 largest gas users in my small ranch will be the Hot Water heater and the baseboard heat (in winter). Cooking for me is insignificant compared to heat and hot water...

Jay
 

Chris PC

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I work for a Solar installer. We've installed several solar hot water systems. Solar Hot Water has a great ROI. Solar PV requires that you are either off-grid, or your state has a good renewable energy feed-law or economically beneficial net metering arrangement.

PM me and I can answer some of your questions. In fact, I'd love for you to ask me questions. Its good to hear what different people need and to try and figure things out for individual situations.
 

Jay H

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I think NJ has a pretty good solar rebate program..You can save up to about 60% of installation costs and since this is not california ;), there's less people to fight for the rebate pool. California, from what I hear typically runs out of money each year (it get's refreshed each year). I believe in NJ, you get about $5.50 back per watt for installation on a solar PV system where installation (professionally) averages about $8 per watt. So for a 2kW system that is about $16k to $20k you can get a bunch of it back. Panels are supposedly guaranteed for 25 years and with net metering, you can sell power back to "the grid".

Chris, cool, I'll PM you with more specific information. I am trying to be as green as possible, when it saves me money, it's just bonus. :)

Jay
 

Fokus_42

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Is there info for the temperature of solar panels and domestic boiler? For the different season...? Something with days, tables, graphics?
This data will help to people to calculate the efficiency in accordance of energy price.
 

Jay H

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If you call a solar installer, they have a device that can estimate your typical solar coverage for a given day and season which is determined by amt of tree cover you have as the sun sweeps the sky and you given latitude (to a degree). the sun is lower in the sky for us northern dwellers in the winter, etc. etc.

Lots of different effects can change your solar efficiency, although for the solar collectors to heat DHW, the needs are a lot less than a PV electric system which needs more coverage. Solar to heat a domestic heating unit like a hot water boiler is less popular because most Domestic boilers run at a much higher water temp (~160degF) than for potable use, unless it's for a suppliment to an existing system or perhaps some radiant heating systems, which I'm unfamiliar with the requirements.

Jay
 

KevinGress

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For those interested in DIY:

Welcome to OTHERPOWER.COM has a lot of references and information about the subject.

I've thought about heating my water either by solar or wood-fire, as my wife's spa tub goes through hot water quickly. And the methods seem a lot cheaper and easier to implement than electricity.
 

Mort Corey

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I think I'm missing something in the equation.....understand the getting green(er) part but fail to see how burning wood is a desireable aspect. FWIW, here in the PRK, buring wood in a stove or fireplace is soon to become a thing of the past. We will be exporting this to your area in the future.....beware.

Mort
 

Fokus_42

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I mean recorded results from different solar panel systems, from different places, during the year. Tables, graphics....
What profit will have sun tracker system compared to static models?
 

Jay H

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Wood is a renewable resource, and the carbon itself is neutralized from the life of the tree before it was harvested for use as firewood. New Post-EPA woodstoves, boilers, also burn much cleaner and more thoroughly than the smoke dragons of the 70s, which means you'll get more BTUs out of a piece of wood and will burn less and burn cleaner. Fireplaces are not the same as air-tight stoves or inserts.

Jay
 

Mort Corey

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Ok Jay, I'll buy that. The powers that be in this state aren't into technology though. The proposed laws coming about will negate all stoves, etc....even burning the pellet type. The only time wood will be allowed to be burned is in the yearly forest fires. Yeh, it's whacky, "but we've got to do something".

Here, Edison does have net metering, so I've been looking into PV cells for a while....still $20K with subsidies to do my house. There's something in a film substrate that looks promising as a substitute for the rigid PV panels, but I'm not sure it's ready for prime time. It'd sure be easier to install and maintain in my enviroment.

Mort
 

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