solar-thermal panels

[crazyal]

So far I haven't puled the trigger. Maybe it's the temps up here, -40 in the winter to 100 plus in summer and the temp of the water, but a number of people I talked to who have the 'regular' panels (copper tubes) have all told me they worked well for about 10 years and then started to leak. While they were able to repair the leaks each time meant draining out the antifreeze and just got to a point where it was too much trouble so they no longer used them. Now most of the panels I've seen look very white like it's not glass but plexi or something covering the face of the panel. That could mean they are not expensive panels.

Most of the local dealers around here I just don't trust. They run ads on the radio saying how in a few years you can pay off solar electric panels. After looking into it and finding out I needed to invest $36k into a system and may get $6k back from the gov for a system that has a life expectancy of about 30 years it's barely a break even option in a state that just doesn't get the sunshine like some of our southern states.

One local dealer said he didn't sell the Evac tubes because they tend to get covered with snow, not really an issue for me, and then quickly moved to electric panels so I lost interest. Until I found someone who can give me an honest opinion I'll probably just wait as my costs of heating water really aren't too bad.

 

[tandttravis]

I have a closed loop glycol system, and live in the wasatch mountains of northern Utah. My system consists of 2 viessmann flat plate collecters, a HT Products 80 gal indirect tank, with boiler backup, a Callefi differential controler,A thermostatic mixing valve, and a Grundfos pump(120v). I built my house 2.5 years ago, and planned ahead for the system, with the install of an indirect water tank(indirect meaning the water is heated via a heat exchanger, so there is no flu in the top of the tank, to lose heat through) and roughed in piping to my roof. I agree with earlier posts about evacuated tube collecters, in my opinion, they are not worth the extra expense. My system delivers 75-80% of my family of 4's hot water needs, averaging of course, the system delivers 100% in the summer months, and less in the winter. My panels are orientated 17 degrees off of true south(to the west) and pitched at 45 degrees. I've read in earlier posts about heat dump methods,but what sold me on my system, is that with only 2 panels, and pitched at 45 degrees for optimal winter gain, it greatly helps to keep the system from over heating in the summer, so I haven't needed a heat dump as of yet. My indirect tank is usually at 170 - 180 degrees in the summer, so I'm definately close to maxing out at times, but has not been a problem as of yet. Like I mentioned earlier, I have a mixing valve installed on the outlet of my indirect tank, which adds cold water to the hot, to insure the water never exceed 130 degrees to my household fixtures.

I have done a tremendous amount of research on the subject, and would be happy to answer any questions, just PM me, as I'm not always checking the forums

I posted about my system last year, do a search for solar hot water in the projects forum.

 

[Raspy]

It sounds like you guys have great systems that you understand well. I like that! Solar heating is such a wonderful addition to a home when it really produces some good results. Unfortunately it is only seen as a business oportunity for some and a chance to make a quick buck. Or sold by someone with good intentions that experiments at the homeowner's expense. This is the problem I've been up against since the 70s.

Now the PV companies are becomming very succesful. I don't do PV on homes, but have been informally asking everyone I can how they like it, what the payback is and what problems they've had. Very interesting indeed.

I get every answer from "I don't know, but I feel like I'm doing my part", to "definitely not worth it because of the problems" to "it's great". Some staunchly defend systems that do nothing, while others monitor every penny. And some put the systems in, just so they can justify using a lot more electricity. Builders install systems just as a sales pitch and put the equipment in the most ridiculous positions on roofs never intended for them.

It seems in many cases you can't save enough to pay the interest on the loan. Or equipment fails that is no longer under warrantee and kills the overall savings. Then the installers send out notices that the collectors must be cleaned and some maintenance done. Unfortunately, this cost approximately equals the annual savings.

I think we are in the beginning of a great shift in consciousness about energy in general. We won't give up anything, but we must find ways to do it differently. In the beginning it was all driven by tax breaks, but eventually it will be driven by energy costs. Hopefully, it will also be driven by the need to be independent of those we buy oil from.

 

[crazyal]

When I built my house a few years ago I made sure I could tie a system into it. The roof pitch is 12:12 and it positioned it so I have a roof facing as close to south as possible.

I have a direct vent oil fired Bodurus boiler sitting atop a 57 gallon tank they make. Having a mixing valve on the output is code. I have it set up so I could add a second tank that feeds the 'cold' water to my primary tank. I also made it to use a pump to circulate water between the two tank when the solar tank gets above the set point of my primary tank.

Any system I install I would like it to be as maintenance free as possible. I don't mind working on things but it always seams like everything needs to be worked on at the same point in time.

 

[Raspy]

crazy,

I like the 12:12 roof pitch for the panels.

I install a lot of indirect DHW systems in the new homes I work on. These boilers also do the radiant heat.

The boilers around here now are all high efficiency and run on natural gas.

I'm building a new home for my wife and I on five acres in northern Nevada at about 4900 feet elevation. It will be in slab radiant and I want to use oil for the heat source, so I'm beginning to look for a high efficiency condensing boiler that runs on oil.

We're now living in the little guest house on the place that is only about 430 sq.ft. It has an electric hydronic radiant system in the kitchen/bath and a wood stove. With R38 insulation and double pane windows it's actualy hard to keep the temp cool enough even with the smallest fire. We keep wondering why we need to finsh the big house instead of just making it a shop for projects. Meanwhile the steel is going up.

 

[magicheater]

It sounds like you guys have great systems that you understand well. I like that! Solar heating is such a wonderful addition to a home when it really produces some good results. Unfortunately it is only seen as a business oportunity for some and a chance to make a quick buck. Or sold by someone with good intentions that experiments at the homeowner's expense. This is the problem I've been up against since the 70s.

I got advice from those same people with good intentions and put in sand beds. I have overcome the poor performance and made them useful again. It took a few years of experimenting but ok with it now and probably would use again now that I understand the requirements and dynamics better.

I think we are in the beginning of a great shift in consciousness about energy in general. We won't give up anything, but we must find ways to do it differently. In the beginning it was all driven by tax breaks, but eventually it will be driven by energy costs. Hopefully, it will also be driven by the need to be independent of those we buy oil from.

I agree Wetspirit, has been happening for a few years but the masses are getting bombarded with going green, remember that only one letter separates green from greed! I read your other post about your new house, I have had the same thoughts about tiny house and big garage for years!! Good luck with the project and share some pics if you will so we can learn even more!

 

[crazyal]

My bodurus is a direct vent but isn't the condensing version. I got the computer control for it that controls things like an automatic mixing valve for the radiant heat. t uses the out door temp to decide how hot the water needs to be as well as monitoring the DW temp to keep it up to temp. I figure by having the water circulation between the primary tank and the solar tank the computer will be smart enough to know not to run the boiler. I went with oil because I'm at the top of a long driveway and I can always buy oil if I run out. I don't have NG as an option and propane needs a truck for delivery.

My house is a post and beam built with foam panels, if you have a chance look into stress skin panels. I have radiant heat throughout but I also have 42 acres of hardwoods so I mainly use the wood stove. Even in the -40 temps we reach in Northern VT I only use 2 to 3 cords of wood. So basically my boiler has turned into an occasional back up to heat the house and how I heat my domestic hot water. I use about 150 gallons of oil a year so there's not too much in savings with solar panels for me. But like you said we need to be moving away from oil and I like the idea of not having to pay for hot water.

 

[magicheater]

My bodurus is a direct vent but isn't the condensing version. I got the computer control for it that controls things like an automatic mixing valve for the radiant heat. t uses the out door temp to decide how hot the water needs to be as well as monitoring the DW temp to keep it up to temp. I figure by having the water circulation between the primary tank and the solar tank the computer will be smart enough to know not to run the boiler. I went with oil because I'm at the top of a long driveway and I can always buy oil if I run out. I don't have NG as an option and propane needs a truck for delivery.

My house is a post and beam built with foam panels, if you have a chance look into stress skin panels. I have radiant heat throughout but I also have 42 acres of hardwoods so I mainly use the wood stove. Even in the -40 temps we reach in Northern VT I only use 2 to 3 cords of wood. So basically my boiler has turned into an occasional back up to heat the house and how I heat my domestic hot water. I use about 150 gallons of oil a year so there's not too much in savings with solar panels for me. But like you said we need to be moving away from oil and I like the idea of not having to pay for hot water.

I sure would be looking into a wood fired boiler of some sort with storage with all that available firewood. Although sometimes it is easier to buy your energy than exert energy to get it. $450 a year is not bad though for all your hot water AND back up heat! Do you have enough floor area to carry the house heating needs?

 

[GT2]

Back to freeze protection and long system life. The best way to design the system is with a method to drain the collectors by gravity when there is no sun or any kind of failure in the system. Do not depend on power to protect the system! In other words, no recirc freeze protection, no electric valves that take power to drain the system, etc. This will make the system much more reliable and more efficient. My favotite is drain back. This is where there is a small holding tank, approximately 4 gallons. that holds the collector water at night. When the collectors warm up, the circulator pushes the water up to the collectors and the air that was in the collectors is stored in the small tank. Then, when the power fails or when the sun sets, the pump stops and the water drains back to the holding tank and the air moves back to the collector. Beautifully simple, no toxic or expensive antifreeze, no mineral buildup, no pressure in the collectors, etc.

I've been thinking of building a system like this for a while. I'll describe it and you guys can give me some feedback?

Build the system like the guy did here SolarShed in Montana.
An open loop system with a large storage tank.
Run the hot water thru a solar loop inside a propane fired hot water tank and then to radiant floor loops in 1.5" gyp creet on the floors.
For back up I was thinking for using a wood boiler hooked to a copper tube grid (acting as a radiator ) placed into the water storage tank.

This would be for a 4000sq ft home and garage in N. Idaho.

Do you think this would work?

 

[magicheater]

I like the boiler part but will defer to Wetspirit as this is more of his expertise.