Solar panels

skerry

MOD NOTE: I've moved this to a new thread so as not to add confusion to an existing thread.

John.G wrote: »

There is something seriously wrong with your system or the way its configured, the > 40c figure is the collector enabling temperature, once the panel temperature reaches 40C (in your case, I've mine set at 25C) AND as long as there is a differential temperature of say 6c to 10c ( this is settable as well , mine is 7C) between the panel and the store temperature (this probe is located just above the solar coil in the hot water cylinder) the the solar circ pump should start and will continue to run until the differential temperature falls to its switch off point of around 3C to 6c (mine is 3C) ......so the water in the cylinder should continue to rise until the maximum cylinder temperature is reached (settable between say 60C and 95C, I've mine set at 85C) OR until the maximum solar panel temperature is reached (again settable, mine is set at 105C) the circ pump will then stop and the solar panel temperature will then rise very rapidly and in the case of evac tubes can go well in excess of 250C and will eventually cause serious damage to your system, solar fluid degradation, perished sealing washers etc).
I would advise you to get someone to look at your system ASAP as you should have lashings of hot water now, my cylinder temperature is at 77C right now after taking two showers. I have 2 flat plates/150 litre hot water cylinder.

If you wish you might post the controller make/model and also what system you have ie evac tube/flat plate and cylinder capacity and we might be able to suggest a few settings to help you while you are awaiting "expert" help.

There is a pressure gauge located at the solar expansion vessel, what pressure is this showing just now?? it should normally read around 1.5 bar to 3 bar.

Hopefully this should give you some idea of your system

Sorry to jump in OP, I was about to post a query about panels and seen your thread so said I'd ask here first and can start new thread if needed.

My problem is the opposite (or possibly just how that panels are meant to function). Moved into house with panels 6 months ago. Problem I'm having with this weather is that I now have lashings of hot water. The reason this is now an issue is that the hot press is reaching crazy temperatures and the baby's room is right next to it so I have way more hot water than I need and am having trouble keeping her room cool.

@JohnG - you seem to be well versed in the settings on these. I've tried to google settings and can't find anything and also can't see any make or model on the control panel. The water seem to heat to around 85C and the reading for the panel itself is going up to around 137C. Pic below of panel.

I'm wondering is there any easy way to stop the panels producing hot water once I have enough so I don't have what is essentially a giant radiator next to the little ones room.

John.G

skerry wrote: »

MOD NOTE: I've moved this to a new thread so as not to add confusion to an existing thread.



Sorry to jump in OP, I was about to post a query about panels and seen your thread so said I'd ask here first and can start new thread if needed.

My problem is the opposite (or possibly just how that panels are meant to function). Moved into house with panels 6 months ago. Problem I'm having with this weather is that I now have lashings of hot water. The reason this is now an issue is that the hot press is reaching crazy temperatures and the baby's room is right next to it so I have way more hot water than I need and am having trouble keeping her room cool.

@JohnG - you seem to be well versed in the settings on these. I've tried to google settings and can't find anything and also can't see any make or model on the control panel. The water seem to heat to around 85C and the reading for the panel itself is going up to around 137C. Pic below of panel.

I'm wondering is there any easy way to stop the panels producing hot water once I have enough so I don't have what is essentially a giant radiator next to the little ones room.

The simplist way is to access the Controller (if you can identify it, the installer may tell you) and change the max cylinder temperature from its present setting of 85C and reduce it to say 55C/60C, the circ pump will then stop and the solar panels will rise in temperature as I stated in one post, now this isn't good for your system but as its in stagnation now anyway (collector temperature per photo is 135C) it will not make much difference.
If systems were installed properly then they should have a "dump" facility, this system has a radiator through which the solar fluid is diverted by the controller and keeps the system still running and not causing any excessive panel temperatures and you can then set the maximum cylinder to lower temperatures.

I have a very basic but very effective dump system that uses the central heating system, its purely manual but I did a test a few days ago and it was able to reduce the cylinder temperature to 50C.
Simply put, I am able to run my C.heating circ pump without running the (oil fired) burner. I open the motorized valve on the coil in my hot water cylinder, start the circ pump and circulate the water to two down stair radiators so the heat is transferred from the coil to the radiators, the room temperature doesn,t rise noticeably as its quite cosy as it is right now. Of course the heat quantity removed is limited by the coil size but its quite adequate for my 2 flat plates.
It may be more difficult to arrange this with a gas fired boiler and full zoning but its certainly possible, there may be someone reading this who can help. The biggest problem with gas firing is that the circ pump is now normally integrated in the boiler itself and one just can't start playing around with this.

John.G

Here is a old thread that my help.. https://www.boards.ie/vbulletin/showthread.php?p=80219571

freddyuk

Systems without any bypass facility will now be self destructing all over the country because this weather was never meant to happen.

Altering the controller on a vastly oversized system will not help as this will turn off the pump and the solar collectors will keep heating in "stagnation" way beyond their design parameters. Your only solution is to cover the panels temporarily leaving enough for your storage capacity. Having the system overheating will turn the glycol to a tarry mess and destroy the pump and other fittings which will be hard to clean up.
I have been advocating by passes and decent solar fluid for years but now chickens are home to roost. The newer self regulating solar collectors which can reduce their output automatically (Kingspan etc.) should be solving all this problem but I have my doubts about these too.

John.G

freddyuk wrote: »

Systems without any bypass facility will now be self destructing all over the country because this weather was never meant to happen.

Altering the controller on a vastly oversized system will not help as this will turn off the pump and the solar collectors will keep heating in "stagnation" way beyond their design parameters. Your only solution is to cover the panels temporarily leaving enough for your storage capacity. Having the system overheating will turn the glycol to a tarry mess and destroy the pump and other fittings which will be hard to clean up.
I have been advocating by passes and decent solar fluid for years but now chickens are home to roost. The newer self regulating solar collectors which can reduce their output automatically (Kingspan etc.) should be solving all this problem but I have my doubts about these too.

I would agree, IMO no solar grants should be given unless a dedicated heat dump, properly sized, was/is fitted as especially E.tube systems can stagnate and overheat in relatively moderately sunny weather if there is little/no hot water demand.

skerry

John.G wrote: »

The simplist way is to access the Controller (if you can identify it, the installer may tell you) and change the max cylinder temperature from its present setting of 85C and reduce it to say 55C/60C, the circ pump will then stop and the solar panels will rise in temperature as I stated in one post, now this isn't good for your system but as its in stagnation now anyway (collector temperature per photo is 135C) it will not make much difference.
If systems were installed properly then they should have a "dump" facility, this system has a radiator through which the solar fluid is diverted by the controller and keeps the system still running and not causing any excessive panel temperatures and you can then set the maximum cylinder to lower temperatures.

I have a very basic but very effective dump system that uses the central heating system, its purely manual but I did a test a few days ago and it was able to reduce the cylinder temperature to 50C.
Simply put, I am able to run my C.heating circ pump without running the (oil fired) burner. I open the motorized valve on the coil in my hot water cylinder, start the circ pump and circulate the water to two down stair radiators so the heat is transferred from the coil to the radiators, the room temperature doesn,t rise noticeably as its quite cosy as it is right now. Of course the heat quantity removed is limited by the coil size but its quite adequate for my 2 flat plates.
It may be more difficult to arrange this with a gas fired boiler and full zoning but its certainly possible, there may be someone reading this who can help. The biggest problem with gas firing is that the circ pump is now normally integrated in the boiler itself and one just can't start playing around with this.

Thanks for reply John G

Presume the controller is the panel I attached as pic? I was hoping to research this a while back to see if I could get user manuals etc. but next to impossible to get info, make harder as I can't see and make or model on the controller.

How do you mean by 'in stagnation' at 135C, sorry completely new to this and only feeling my way around. Would 135 be considered an excessive panel temperature?

Any ideas on what the 'dump' facility should look like or where it would be kept? Haven't had a chance to poke around the attic for anything connected to panels regards a dump.

Have an oil fired boiler so probably need to get someone to look at system to see if a dump similar to yours is possible at the moment.

John.G

skerry wrote: »

Thanks for reply John G

Presume the controller is the panel I attached as pic? I was hoping to research this a while back to see if I could get user manuals etc. but next to impossible to get info, make harder as I can't see and make or model on the controller.

How do you mean by 'in stagnation' at 135C, sorry completely new to this and only feeling my way around. Would 135 be considered an excessive panel temperature?

Any ideas on what the 'dump' facility should look like or where it would be kept? Haven't had a chance to poke around the attic for anything connected to panels regards a dump.

Have an oil fired boiler so probably need to get someone to look at system to see if a dump similar to yours is possible at the moment.

You don,t say whether its a evacuated tubes or a flat plate(s) system installed. Evacuated tubes will give a higher output because the are under vacuum conditions with less loses but if no heat is being removed from them then they can reach very high temperatures and the final temperature reached which I think is called the stagnation point can be over 250C, flat plates on the other hand will not reach such high levels, mine "only" reached 140C when i tested it a few years ago on a very hot day.
I would consider any tube/panel temperature that consistently exceeds 110C as being excessive, the temperature should never be higher than say 20C higher than the hot water temperature, so if you have a water temp of 60C then the panel temperature should not be > 80C and more likely will only be 65C to 75C. The problem arises when the max cylinder temperature is reached and the circ pump cuts out, the tube/panel temperature can and will then reach excessive temperatures and that's why a heat dump should be fitted.

Re Heat Dump (If you have one) : You should have a dedicated (dump) radiator somewhere (maybe in the attic) when the maximum cylinder temperature is reached the controller should actuate a 3 way valve and divert and circulate the solar fluid through this dedicated radiator to dissipate the panel heat until the cylinder temperature reduces and the system returns to normal.

skerry

John.G wrote: »

You don,t say whether its a evacuated tubes or a flat plate(s) system installed. Evacuated tubes will give a higher output because the are under vacuum conditions with less loses but if no heat is being removed from them then they can reach very high temperatures and the final temperature reached which I think is called the stagnation point can be over 250C, flat plates on the other hand will not reach such high levels, mine "only" reached 140C when i tested it a few years ago on a very hot day.
I would consider any tube/panel temperature that consistently exceeds 110C as being excessive, the temperature should never be higher than say 20C higher than the hot water temperature, so if you have a water temp of 60C then the panel temperature should not be > 80C and more likely will only be 65C to 75C. The problem arises when the max cylinder temperature is reached and the circ pump cuts out, the tube/panel temperature can and will then reach excessive temperatures and that's why a heat dump should be fitted.

Re Heat Dump (If you have one) : You should have a dedicated (dump) radiator somewhere (maybe in the attic) when the maximum cylinder temperature is reached the controller should actuate a 3 way valve and divert and circulate the solar fluid through this dedicated radiator to dissipate the panel heat until the cylinder temperature reduces and the system returns to normal.

Flat plates as far as I can tell. Looks like one panel with 3 sections on the roof. Similar to yours, I've only observed them going to around 138C on the hottest days we've had recently so I'm guessing that's close to max. Water would be 80 ish degrees then.

No real idea on how to operate the controller panel. There is an up and down arrow and when I cycle that it gives COL, S-2, and S-3. At the moment at 12 noon and about 24c outside they are reading as below but I'm not sure what's what or if they are reading what they should be for a day like today other that COL must be panel temp as thats the one that goes to around 138C on very hot days.

COL- 64.2C
S-2 60.4C
S-3 68.1C

There is a Heatcon unit with Grundfoss pump on the wall but again I have no idea whats what. Pic attached. Look like plumbing comes from panels to return on tank and then flow on tank is going back to the pump.

Have to get up to attic to check for any sort of dump but with amount of hot water I'm getting I'd be surprised if there was one.

Thanks for info so far, appreciate it

John.G

skerry wrote: »

Flat plates as far as I can tell. Looks like one panel with 3 sections on the roof. Similar to yours, I've only observed them going to around 138C on the hottest days we've had recently so I'm guessing that's close to max. Water would be 80 ish degrees then.

No real idea on how to operate the controller panel. There is an up and down arrow and when I cycle that it gives COL, S-2, and S-3. At the moment at 12 noon and about 24c outside they are reading as below but I'm not sure what's what or if they are reading what they should be for a day like today other that COL must be panel temp as thats the one that goes to around 138C on very hot days.

COL- 64.2C
S-2 60.4C
S-3 68.1C

There is a Heatcon unit with Grundfoss pump on the wall but again I have no idea whats what. Pic attached. Look like plumbing comes from panels to return on tank and then flow on tank is going back to the pump.

Have to get up to attic to check for any sort of dump but with amount of hot water I'm getting I'd be surprised if there was one.

Thanks for info so far, appreciate it

Yes, that's a flat plate array you've got, those three temperatures you gave are the collector temp (S1) of 64.2c, S2 of 60.4C is the store temperature which is taken just above the solar heating coil and eventually will heat up the remainder of the tank to 68c (S3) (if no usage) and will continue to heat the tank until the maximum cylinder temperature of what looks like in your case to be 80C and then the circ pump will stop and the collector temperature will continue to rise until it reaches its stagnation temperature of 138C.
S3 of 68C is the cylinder top temperature, mine was 70C at 12 noon so everything is operating as it should and a central heating dump should deal with your situation as you have flat plates like mine.
This is possibly the controller type (if not the exact model) that you have...
http://www.evergreenenergy.ie/man/Op_deltasol_bs.pdf

skerry

John.G wrote: »

Yes, that's a flat plate array you've got, those three temperatures you gave are the collector temp (S1) of 64.2c, S2 of 60.4C is the store temperature which is taken just above the solar heating coil and eventually will heat up the remainder of the tank to 68c (S3) (if no usage) and will continue to heat the tank until the maximum cylinder temperature of what looks like in your case to be 80C and then the circ pump will stop and the collector temperature will continue to rise until it reaches its stagnation temperature of 138C.
S3 of 68C is the cylinder top temperature, mine was 70C at 12 noon so everything is operating as it should and a central heating dump should deal with your situation as you have flat plates like mine.
This is possibly the controller type (if not the exact model) that you have...
http://www.evergreenenergy.ie/man/Op_deltasol_bs.pdf

Thanks a million for the info JohnG, I've been struggling to find anything online on these. I emailed that evergreen crowd to see if they could provide any info on controller a while back but got no reply.

Will have a look at manual you sent on and try educate myself a bit more and look into heat dump for the future.

Good to know that they are operating as expected at least apart from the excessive panel temp but that's to be expected with no dump and the weather we've been having

Thanks again