Solar Space Heating - Which Evacuated Tube Is Best?

riccol1966

I have done a lot of research of the past year on how to upgrade my heating system as part of my renewable heating project. I have decided to go with solar evacuated tubes for DHW (domestic hot water) AND to make a space heating contribution. The reason I am doing this is that it makes no sense to me to spend say, EUR8K getting just solar DHW installed, when going a bit further will give me a contribution towards space heating also. Lets face it- most who have done this already have new panels plus a new dual coil cylinder (unless you opt for solartwin or feed direct into your existing tank, which will probably be too small).

There are many threads that say steer clear of this but I am going ahead because it is the only system which gives you 'free' energy once you have paid the capital cost. And I plan to augment this with system initially with my current oil bolier, and swap over to one or more woodchip boilers over time. Payback is not a concern for me; going green is.

So please could I have feedback from anyone who has installed Evacuated Tubes for solar DWH or better yet as a supplement to space heating.

I have seen all kinds of tubes, from the unbranded ones sold by Navitron through to Thermomax, Viessmann Vitosols and the most expensive, which appear to be Paradigma tubes. A recent quote was appx EUR9000 just to buy 40 of these tubes, albeit a large aperture (>8.5 mt2).

Anyone have any systems like this installed, or are they planning to?

Thanks,

Richard.

http://www.richardcollins.net

jobrok1

We have a system link this installed.

Our views on home heating are pretty much the same as yours RICCOL1966. If your going to do it at all you may as well get the most out of it.

We don't have Evacuated Tubes though. We went with Flat Panels.
12sq.m in total. 6sq.m is south-east facing and the other 6sq.m is south-west facing. Only because of the position of the house. Not done purposely.
If we had a directly south facing roof 8-10sq.m would be more than enough.
The water tank is an 800litre combination tank. 600litres for central heating and storage and 200litres for domestic hot water.
Total cost for Panels, Tank, Pumps, installation, etc... was approximately €8,000.

Our back-ups are a 3kW immersion heater in the tank, which we've used probably a dozen times over the last year for about half an hour to an hour at most each time. And a large 19kW solid fuel stove with back boiler. No oil or gas boiler.
The house is only a year old. Concrete! Radiators! Well insulated! No underfloor. This has worked well for us over the last year. A few times over the winter it did get pretty cold, but that's mainly because we are at work until 5-6 in the evening and there is no-one home to light the fire any earlier.

The solar panels kept the water temperature between 30-40 degrees for most of the winter. Once the fire was lit it took only about 1 hour to raise the temperature to between 50-60 degrees. Not the most ideal heating system to use with conventional radiators. It took a while for the house to heat up to a comfortable temperature at times, but not too often...!!!
We'll probably get another back-up in the near future. Maybe a wood pellet or wood chip boiler. Or an air-to-air heat pump, something that's tweeked my interest lately over other space heating systems around.

All in all! Our system works pretty good. Slightly better than we expected during the colder winter months, which is a plus! And WAY better than expected in the summer.

riccol1966

thanks for the reply jobrok1- sounds like overall you are happy with yours, and glad to hear from someone who has gone for this. I see what you mean about supplementing it with solid fuel, thats a good start; in fact my next step once I have the panels installed is to get a woodchip stove with back boiler, which can then augment the heat into the buffer tank.

I have 2 main issues with mine, the first is that one quote is appx EUR9,000 but that only allows for 6.5 sq metes of Viessmann evac tubes, and I am thinking-- is this a large enough aperture to heat the 750lt buffer tank (same as yours, more of less) and give me the contribution towards space heating?

The second issue is that the quote from another supplier is significantly higher, due to the huge cost of the Paradigma tubes, with 40 tubes coming in at appx EUR9000, thats EUR200 per tube !! I wonder if anyone else has these installed, and are they worth the huge premium ?

Richard.

jobrok1

I don't have any experience with the Evacuated tube type panels. But from what I understand they are more efficient in overcast conditions, so Maybe the 6.5sq.m is enough.

Maybe if you design the system to allow you to increase the number of tubes/panels at a later time if it's not quite working as you expected.


One word of warning though. Don't expect to get results from the solar every day. On really cold, wet, rainy, overcast winter days you probably won't get anything at all.

dixiefly

jobrok1 wrote:

I don't have any experience with the Evacuated tube type panels. But from what I understand they are more efficient in overcast conditions, so Maybe the 6.5sq.m is enough.

Maybe if you design the system to allow you to increase the number of tubes/panels at a later time if it's not quite working as you expected.


One word of warning though. Don't expect to get results from the solar every day. On really cold, wet, rainy, overcast winter days you probably won't get anything at all.

Hi jobrok, that is interesting. What make of Flatpanels did you go for & also what type of cylinder?

Thanks

jobrok1

I got the panels from a company called AQUATECH.

https://www.aquatech.ie/store/product_info.php?cPath=31&products_id=186&osCsid=00911769a9e8090e50fef84951633687

We were planning on installing the renewable systems over time, but the more I looked into it I realised it would be a lot easier to install the panels during construction.
So our roof was being constructed and I needed to source panels rather quickly. AQUATECH are half an hour away, had the panels in stock, were reasonably priced and could deliver almost immediately. They are bracket mounted panels. I would have prefered to go with some like SOLARIS and installed recessed type panels, but their delivery times didn't suit.

The tank, if I remenber correctly is a "KSV601/200" 800lt Combination Tank which I got from a company called SOLAR ENERGY IRELAND. I had plenty of time to source this so I checked around intil I found what I was looking for at a good price.

http://www.solarenergyireland.com/

goinggreen

Guys the best tubes on the market to use would be Viessmann. I have researched this and found them the best performing. 3sq M of tubes & a 300Lt T/C cylinder would be suitable for a 3-5 bed person house. I would contact Viessmann Ireland and ask further advise on space heating. Remember all solar manufactures are different , and stay away from Chineese cheap solar. Let us know how you get on.

CJhaughey

goinggreen wrote: »

Guys the best tubes on the market to use would be Viessmann. I have researched this and found them the best performing. 3sq M of tubes & a 300Lt T/C cylinder would be suitable for a 3-5 bed person house. I would contact Viessmann Ireland and ask further advise on space heating. Remember all solar manufactures are different , and stay away from Chineese cheap solar. Let us know how you get on.

You sure about that? IIRC the tubes made by Thermomax in the North were one of if not The most efficient on the market.
Tested by the Swiss Solar institute.

jmtc8

Hi Richard,
We have a 40 tube system installed with a 300ltr tank and find the tubes are very efficient even on cold cloudy days they are working.
There not great in the rain but all systems are this way.
They have only been installed about 2 months but you can see the difference in the water temperature in the controller every day.
We got our system from a company called Connaught Solar, the cost price was very good and the guy that fitted it came back a week later to check everything was ok.

www.connaughtsolar.com

We spent 6 months researching solar water heating before we decided to take the plunge.
There are a lot of companies out there supplying good systems from Europe but we found that a lot of these companies were buying their solar panels from China and re-branding. In fact most glass tubes and panels are made in China and sold throughout the world and one company is building a massive factory in Texas.
Only buy SEI registered products as you may qualify for a grant to help
pay for the system.
Let us know how you get on with your heating as we would be also interested in this if it works.

Good Luck

Fiona

djpbarry

The thread's 2.5 years old folks - I'm guessing Richard's got the info he needs by now.