Are you all pleased with your solar panels for hot water heating

1100010110

Nice weather for it

championc

If your system is not up to max temperature at this stage after these continuous days of sunshine, then your system has a serious issue. My whole tank was at 80 deg C yesterday afternoon. So it's MAX'ed out now.


C

1100010110

No temperature probe at the top of the tank but temp. at base of tank >70degrees, <75 degrees for the past while, boiler hasn't fired in about a month and if anything DHW usage has increased.
Internal room temperatures have been hanging out at 22 to 25 degrees for the past while also, it's all good.

Qualitymark

Fellow came to the door offering solar panels to heat radiators, for €9k-€13k; when I queried this (and his claim of a five-year payback) he said they used a "new chemical". No brochure, no identification of the "new chemical"....!

John T Carroll

championc wrote: »

If your system is not up to max temperature at this stage after these continuous days of sunshine, then your system has a serious issue. My whole tank was at 80 deg C yesterday afternoon. So it's MAX'ed out now.


C

Just saw the post(s) on my EMail, Championc, the circ pump seems to have stopped with the following temperatures....Roof:83C. Bott.Buff:74C. Mid.Buff:75C. Top.Buff:75C. Have you lowered your max cylinder temperature to allow this to happen? or is there another reason?....I didnt see your trends yesterday but if the whole tank went to 80C yesterday then it should attempt to do likewise today?......John

championc

Hi John

I actually had it set to max at 85 so I've reduced it to 75 since plenty of water was being released via whatever safety valves are in the setup and so plenty dripping out from the vent pipe.

The whole store went to 85 yesterday so 75 seemed more sensible. However, I think you saw the data John just when the pump was knocking off because the roof temperature naturally shot up and has been in the mid 150's deg C for the past hour !! The sun has now passed over and it's reducing. But hey, it's a Kingspan system and the Kingspan is designed to auto-vent.

I expected it to go up to about 130 but 150 was a surprise. Aparently, the system and Glycol is safe up to 170 - phew.

josip

I think €4000 - around €1000 grant = net €3100
2011
m2 area - Whatever 18 tubes gives
Due South - 35 degrees pitch
Tubes
250l
No summer heat dump strategy

This year, I've been very happy. Yesterday I blipped the gas boiler to heat the water for the first time since 26th of March. 6 whole months of 100% free water.

The system has been troublesome before now however. Distance between panels and pump caused the pump to burn out, apparently due to conductive heat transfer one summer while we were on holidays. A longer pipe seems to have fixed that, but the pump twice since stopped workiing due to bubbles. We've been told this is more likely to happen because the pump is installed in the attic, not much below the panels.

quentingargan

josip wrote: »

Distance between panels and pump caused the pump to burn out, apparently due to conductive heat transfer one summer while we were on holidays. A longer pipe seems to have fixed that, but the pump twice since stopped workiing due to bubbles. We've been told this is more likely to happen because the pump is installed in the attic, not much below the panels.

The pump is more likely to have suffered stagnation where the fluid in the panel and nearby turned to steam and moved to the expansion vessel. A heat dump would prevent this (unless there is a power cut) but you can also mitigate this by ensuring that stagnation doesn't go through the pump by the use of a high temperature non-return valve.

leo738

This is a realtime feed of my system. The text at the bottom of the page is difficult to read but the details are there.

http://xively.com/feeds/61072

championc

And mine

https://xively.com/feeds/1928576781

John T Carroll

leo738 wrote: »

This is a realtime feed of my system. The text at the bottom of the page is difficult to read but the details are there.

http://xively.com/feeds/61072[/QUOTE]

Hi Leo,
I was looking through your interesting trends just now, I cant see in any period where SI (Solar Fluid temperature In) is higher than CB (Bottom of Cylinder temperature). Today, at 1200 hrs, SI was 42.0C (SO was 40.5) and CB was 46.6C. At 1300 hrs, SI was 44.7C (SO was 42.7) and CB was 53.1C.
Is there some factor being used in the SI and SO temperature indications? or maybe I'm just not interpreting the readings correctly. John

championc

Correct John

Looking at it right now, Leo's bottom of the cylinder is showing as 47 while Solar Fluid In is saying 43 and with both increasing, it doesn't make sense.

Qualitymark

How's the price of solar hot water systems moving these days, lads? Dearer or cheaper?

wonga77

Are there grants available anymore for solar panels? I guessing not?

BryanF

wonga77 wrote: »

Are there grants available anymore for solar panels? I guessing not?

€800

gooseygander

BryanF wrote: »

€800

I take that this grant is only available to renovations and that a new build does not qualify, is this the case ?

BryanF

gooseygander wrote: »

I take that this grant is only available to renovations and that a new build does not qualify, is this the case ?

No new build grants. The Costs just keep rising..

championc

BryanF wrote: »

No new build grants. The Costs just keep rising..

Maybe so but with the right system setup correctly, it will be paying fpr itself in about 10 years (based on current energy prices) or maybe less.

Follow my systems performance at

https://xively.com/users/championc/develop

JDoubleU

I'm interested in solar thermal panels and the savings they provide. It would be great to hear from people (not companies) who have realised actual savings from solar thermal. I'm interested to know:

Your savings are in Euro.
If you have tube or flat plate
What direction they face.
Hot water or hot water & heating
What part of the country you live in.
What convinced you to buy that particular panel e.g. were you fed bs on savings etc. I have come across one company who shall remain nameless and have to say I'm not impressed with their BS.

I know savings will vary for each home depending on use but it would be great to see differences and get a real picture of what's out there.

Thanks in advance.

BryanF

JDoubleU wrote: »

I'm interested in solar thermal panels and the savings they provide. It would be great to hear from people (not companies) who have realised actual savings from solar thermal. I'm interested to know:

Your savings are in Euro.
If you have tube or flat plate
What direction they face.
Hot water or hot water & heating
What part of the country you live in.
What convinced you to buy that particular panel e.g. were you fed bs on savings etc. I have come across one company who shall remain nameless and have to say I'm not impressed with their BS.

I know savings will vary for each home depending on use but it would be great to see differences and get a real picture of what's out there.

Thanks in advance.

have read back through this thread

JDoubleU

Bryan, I've already read the thread and while there's some useful info in it, there's not much on savings. The new thread was for specifics on savings.

championc

I think a well installed, properly sized, well located, Evac Solar Tube system should pay for itself in about 10 years

goat2

at least when i asked a guy about this solar water heating system,
fair dues to him,
he told my roof was not suitable due to direction, he saved me money and time as well as being disappointed,
when i consider that a load of logs will heat radiators and hot water, at least the money will last a fair few yrs with a good output

John T Carroll

JDoubleU wrote: »

I'm interested in solar thermal panels and the savings they provide. It would be great to hear from people (not companies) who have realised actual savings from solar thermal. I'm interested to know:

Your savings are in Euro.
If you have tube or flat plate
What direction they face.
Hot water or hot water & heating
What part of the country you live in.
What convinced you to buy that particular panel e.g. were you fed bs on savings etc. I have come across one company who shall remain nameless and have to say I'm not impressed with their BS.

I know savings will vary for each home depending on use but it would be great to see differences and get a real picture of what's out there.

Thanks in advance.

If you read my very first post and then go to page 3 of my posts to "2013 Solar output" then go to Cell E421 of the attached Spreadsheet then that will give you a very good feel, in my opinion, for the real savings of a Flat Plate Panel set up. If you want to compare it with the "usual" Three Flat Plate + 300 litre cylinder just multiply by a factor of 1.5. An Evacuated Tube Array, should give an additional 25% to 30% increase in savings, in both cases.

db

cost $6K approx
year of installation 2013
m2 area 40 tubes
orientation SW 35 degree slope
flat plate or tubes tubes
cylinder size 300L
summer heat dump strategy ( if any ) None

Moved in last August and delighted with the solar performance. Water would be hot enough for showers up till end of October, about 40deg at the top, a bit cooler in Nov and down to about 20deg in Dec with the occasional good day when there was a bit of sun. Since the start of Feb the water in the evening would increase week by week and it is above 40deg most days at this point. Last week we had a couple of days >50deg top and bottom of the cylinder.

Even when there was little heat from the sun in the middle of winter, it took very little to heat the water with the oil boiler. We never had to run the boiler for more than an hour to bring the water up to temperature.

Qualitymark

db wrote: »

cost $6K approx

Dollars?

Jakey Rolling

Had ours installed as in 2012 as it was a new build and more or less required to meet the Part L regs for renewables.

Cost €5000 inc cylinder
30 tubes with parabolic reflector
South facing roof at 35% pitch
300l cyclinder
No heat dump


What I can comment on is this.
We save about the equivalent of 300 litres of oil over the year.
This is about €250 at current prices.
So payback would be 20 years nominally
That's ignoring any maintenance, fluid replacement, eventual pump replacement.

So I wouldn't see solar thermal in any way as a cost saving measure, but it does feel good to have the tank at 65C on a day like today.

Our setup appears to be slightly oversized.
Good in that we had water up to 40C in Dec and Jan on solar alone.
Bad in that it spends most of the time stagnating, reaching 195C in summer. Don't believe this is good for the anti-freeze additive witch states max temp of 180C.

The slight problem with this is that the system stops pumping at 120C, so if I went and had a bath now, using up the hot water, the solar won't start reheating the tank until the top end drops back below 120C in the evening. Not normally a problem, but could catch you out at times.

josip

Jakey Rolling wrote: »

Had ours installed as in 2012 as it was a new build and more or less required to meet the Part L regs for renewables.

Cost €5000 inc cylinder
30 tubes with parabolic reflector
South facing roof at 35% pitch
300l cyclinder
No heat dump


What I can comment on is this.
We save about the equivalent of 300 litres of oil over the year.
This is about €250 at current prices.
So payback would be 20 years nominally
That's ignoring any maintenance, fluid replacement, eventual pump replacement.

So I wouldn't see solar thermal in any way as a cost saving measure, but it does feel good to have the tank at 65C on a day like today.

Our setup appears to be slightly oversized.
Good in that we had water up to 40C in Dec and Jan on solar alone.
Bad in that it spends most of the time stagnating, reaching 195C in summer. Don't believe this is good for the anti-freeze additive witch states max temp of 180C.

The slight problem with this is that the system stops pumping at 120C, so if I went and had a bath now, using up the hot water, the solar won't start reheating the tank until the top end drops back below 120C in the evening. Not normally a problem, but could catch you out at times.

• Since it was a new build, you would have needed a cylinder anyway, regardless of panels, so I think you're being hard on your system by including the full cost of the cylinder.
• Were there any grants for solar still around in 2012?
• Have you considered installing a blind for your panels? I remember seeing them advertised but can't find them now.

freddyuk

A simple by pass via a radiator is a cheap way of diverting the sting from the system. One diverter valve some pipe and a standard radiator cost about the half the cost of having the fluid replaced. Most decent controllers have this function included. It helps prevent all the system components being stressed leading to early failure. "A properly designed system does not need a bypass" is often quoted but how can you design a thermal system that provides sufficient hot water in winter and does not stagnate in summer. It only takes one very hot day to have a steam event and cause damage to glycol, expansion vessel etc. if there is no where for the heat to go. There is the argument that in an attic the ambient temperature is aready too high to be able to dump the heat but we are talking 120c + in the system. I would rather have the dump and have a good chance of saving my system if I am away on a belter of a day.
Kingspan have an inbuilt "safety" system but they do not really want to have to pay out if it fails hence the warranty terms and it's effectiveness is in some doubt. Maybe others will have an opinion on that.
There are high quality Glycol solutions that do not need replacing after stagnation but I doubt any standard system will have this used.
Using blinds is not an option if the panels are on the roof and automatic blinds are going to be likely to fail after a couple of winters.
Just my opinion but interested in expert views on this.

Jakey Rolling

freddyuk wrote: »

A simple by pass via a radiator is a cheap way of diverting the sting from the system. One diverter valve some pipe and a standard radiator cost about the half the cost of having the fluid replaced. Most decent controllers have this function included. It helps prevent all the system components being stressed leading to early failure.

Thanks for that - I will have to quiz my plumber on this, as you say, the system components are being stressed by this continual stagnation.

What I can't work out is what size radiator would be needed to effectively dump the excess. Given that the aperture of the tubes is approx 3m2 then at most you would expect continuous 3kW heat to be transferred, if solar radiation is approx 1kw/m2. However the controller often shows power up to 20kW, presumably based on temp difference, flow rate and specific heat capacity. I'm not so keen on plumbing a rad in a cold attic. Wouldn't it need glycol in the circuit too?