LVP Thermodynamic solar Panels

just do it

Braka
I look forward to your report around next March

dathi

hi braka just a quick question while i understand that you have a manual switch that allows you to turn on the immersion when you want to raise the temp for legionnaires ,do you know whether the immersion has the ability to turn its self on when the system detects that there is not sufficient heat available from the roof panel to heat the water to the set temp, as most air source heatpumps have this ability built in.

freddyuk

The immersion is manual only AFAIK. The legionella requirement is 60c I believe but 65c will certainly do it. A constant 55c will keep the risk controlled but any long dead legs may be an issue whch is unlikely in the domestic situation.
The roof panel has little effect in cold weather so the heat pump just runs longer as the efficiency is lower. That's the drawback and why we think the power draw will increase as the COP falls away. There are only 24 hours in a day so that is the point where it will fail!! If it runs at a COP of 1.1 and it needs 29,700 BTU's to raise the temperature by 30c (ie 25c - 55c) then this equates to 8.7 kWh. If the power available is 360w
then it will take 8700/360 = 24 hours to heat the water. Spooky! Where did i go wrong.??

shane0007

Only a few Legionnaires can survive at temperatures between 50-55C. Above this none can survive, so cylinders are normally set to 60C. Above this temperature you should really fit an anti-scald valve as the young and elderly can be affected at temperatures above this.

Bringing the temperature to 60C at least once a week will also ensure no Legionnaires.

Condenser

The running cost of these panels is not the biggest problem you guys may come up against. You'll possibly be replacing compressors regularly. When a refrigeration system is designed it has to be designed to very defined parameters. When the refigerant is in its low pressure phase and cold it needs to pick up a certain amount of heat to raise it above its boiling point but not too much either. Ground source units would have this under control because the ground conditions are pretty static and therefore a valve regulating the flow of refrigerant can maintain the superheat required. An air to water unit also has an expansion valve but it can also regulate the fan speed in order to maintain the superheat required.
These panels operate over a huge range of temps with no regulation outsice the expansion valve possible. If the temp is high and too much superheat is picked up across the panel it reduces the efficiency and removes the cooling effect of the refrigerant which can cook the compressor. If its too cold and not enough superheat is picked up the refrigerant won't boil off fully in its phase change from liquid to vapour. This means droplets of liquid will enter the compressor and would be akin to throwing bits of gravel into it.
Both will result in compressor failure.

freddyuk

The "cost" of these units is the compressor which is a modified unit and if it fails the unit is non economic to repair. Can you back up your information with evidence I can read through?
Thanks

Condenser

freddyuk wrote: »

The "cost" of these units is the compressor which is a modified unit and if it fails the unit is non economic to repair. Can you back up your information with evidence I can read through?
Thanks

I doubt the compressor is modified to be honest. What modifications are they quoting because I know of none that can overcome the problems above.I didn't quote any evidence, I was just talking from the standpoint of an experienced refrigeration engineer. If you need to know about the effects of excess superheat or refrigerant not boiling off completely before it enters the compressor a quick google will suffice.

freddyuk

Well they give it a fancy name - "heat block" or something like that. I did have the testing paperwork from Intertek in Malaysia but I cannot find it now. I accept your knowledge and will do a bit of googling. If true it should be made known to the many who are considering moving into this lucrative market.
Sadly the customers will be the losers every time. Still lets wait for Brakas news after the New Year.

braka

freddyuk wrote: »

The immersion is manual only AFAIK. The legionella requirement is 60c I believe but 65c will certainly do it. A constant 55c will keep the risk controlled but any long dead legs may be an issue whch is unlikely in the domestic situation.
The roof panel has little effect in cold weather so the heat pump just runs longer as the efficiency is lower. That's the drawback and why we think the power draw will increase as the COP falls away. There are only 24 hours in a day so that is the point where it will fail!! If it runs at a COP of 1.1 and it needs 29,700 BTU's to raise the temperature by 30c (ie 25c - 55c) then this equates to 8.7 kWh. If the power available is 360w
then it will take 8700/360 = 24 hours to heat the water. Spooky! Where did i go wrong.??

I'm not so sure of your comment "The roof panel has little effect in cold weather..".
Originally when researching this system, one of the Q's I had was what happened to people who had this system during that very cold December 2010-Jan 2011 period when temperatures plummeted down to -17 Deg. C.?

The answers were emphatic in that in all cases lots of hot water was available even on the coldest days!
I was told that this panel works at night and in cold weather and that its not exactly a "heat pump" system in its truest sense....but I'm not an expert in what it is or isn't....I just want it to provide good value hot water for the house and so far its doing the job.

Re the discussion on the the compressors and the need to replace them often??
All I know is that I received a 10 year guarantee on all parts of the system which seems pretty ok. My fridge and freezer only came with a 1 year guarantee!

Like we both said already...lets wait and see.
I will try and get more data to you before year end, as we will have the shortest days by then and probably colder weather.
BTW, its great to see the views of so many well informed contributors on this forum and that's why I am happy to pass on my findings for comment.

freddyuk

There are people on here who understand fully how this system works better than I do. However the question you should ask is what was the COP (efficiency) at -17c?
The panel could be in your attic and it would still work but we are trying to establish how efficient it is.
Also can you advise if the guarantee is from the manufacturer or the supplier?
I would be interested in seeing a copy.
Thanks

Condenser

You can 100% guarantee that the COP would be no better than an immersion at -17 evaporating. And your evaporating temp is normally about 8C below the temp of the area you are extracting from. In this case I would expect it to be much more than that given that any moisture in the air will stick to the panel and form ice once the evap temp gets below zero so the rate of thermal transfer would drop. And given that there is no means of defrost besides off cycle I don't see how you get rid of that.

Your COP is mainly dependent on three things. Your evap temp, your condensing temp and the efficiency of your compressor. Normally these things have a standard rating point, so at an evap temp of -5 and a condensing temp of 35 you will have a COP of say 3.8. For every degree the evap temp drops, efficiency will drop about 2%. For every degree the condensing temp increases the efficiency drops about 2%. So given you scenario of -17 (evap temp not outside temp which will be much higher) and a condensing temp of 55 you would have a 24% drop in efficiency on the evaporating side and a 40% drop in your efficiency on the heating side giving you a combined drop of 64% leaving your COP at 1.216

paddy147

Just thought I would post this,after I found it lurking on my old SD card.

The control panel slots on over this and is held in place with 2 small allex key screws on each side.

freddyuk

So Paddy147 have you got a 10 year guarantee from the manufacturer for your unit? Or from supplier. Would you share the details?
Thanks

deandean

paddy147 wrote: »

Just thought I would post this,after I found it lurking on my old SD card.

The control panel slots on over this and is held in place with 2 small allex key screws on each side.

:eek: Last time I saw that it was clung onto Ripley's face laying an egg in her tummy....

Condenser

Nothing special about that compressor. Just a standard L'unite Hermetique or equivalent that you find in any small refrigeration cabinet

freddyuk

So does it surprise you it is being used in a situation where it is operating at or beyond it's designed capabilities? ie. It is not specifically designed for coping with large temperature variations and keeping a COP of 3+

Condenser

Yes and no. Those compressors are dirt cheap so replacing one for a supplier would cost buttons. The labour would cost much more. The design evap temp is more likely to be -10 than -5. I assume its running 134a? The most likely problem for that compressor is that it will cook itself on warmer days due to excessive superheat. With the design of the system it would be impossible to have a compressor that would be within design conditions at all times due to the range of temps it will operate under. Much in the same way that an air conditioning unit designed for malaysia wouldn't be sold in europe. Two completely different design criteria.

Feel your fridge compressor when its been running for 20 mins and then expand the design range to what your dealing with here and you'll get the idea.

freddyuk

So no way a manufacturer would offer a 10 year guarantee so this is likely to be a supplier backed guarantee to push sales which is possibly insured or more likely not. So that can lead to consumer problems in the event of a failure. I wish owners would offer us the details as I love small print.

Condenser

freddyuk wrote: »

So no way a manufacturer would offer a 10 year guarantee so this is likely to be a supplier backed guarantee to push sales which is possibly insured or more likely not. So that can lead to consumer problems in the event of a failure. I wish owners would offer us the details as I love small print.

No manufacturer of a mechanical part will give a 10yr warranty. The industry standard is 1-2 years. Mainly 2.

BryanF

http://www.solarpowerportal.co.uk/news/gemserv_suspends_solar_thermodynamic_products_mcs_registration?goback=.gmp_3603792.gde_3603792_member_183600344
this may be of interest to those unsure about Thermodynamic 'solar' Panels

freddyuk

That is really an argument about getting UK Green Deal cash from a system which has been classified as a "solar thermal system" to ensure it qualifies for grant money because the MCS have rejected "heat pumps" from any government supported scheme. (due to their inefficiencies). The MCS are fools and the whole system is in disrepute but someone screwed up letting the system qualify under the solar keymark classification.
Take the "solar panel" away and it will still do the job so it is categorically not a solar thermal device. Remove the solar tubes from a thermal panel and it will not work! Hardly rocket science.
I believe it is being pushed in Ireland because in this climate there are never any real hots or real colds so the system should survive without too much stress. The hot water will keep coming if it works within it's design parameters and sometimes it will be efficient and sometimes it will be inefficient but most customers will be unaware. (accept for the large repayments). The test comes when the weather is constantly outside the norm and the system has to cope with very cold spells of weather. Solar thermal just needs sun and does not care if it is hot or cold ambient but extracts free energy to produce hot water and qualifies for grant assistance. If turning your immersion on to heat water qualified for grants then the incentive system would be bust. The Heat pump uses varying amounts of electricity to heat water so how can that compare with a true solar thermal system? If you turn off the electric will it work? No!

fuchia

Hi All,

I finished my house back in January this year. Thermasol / LVP installed a 250 L buffer tank and thermodynamic block and one panel on the roof to run the hot water. They also installed a 500 L buffer tank, thermodynamic block and two panel's to run the under floor heating.

Every day I have been recording the temperature in each room, outside temp, buffer tank temp and power usage. I have also recorded after sales care.

I will tidy up the spread sheets and post them when I get a chance. Should be of great interest to anyone considering using this system.

maradonas

i can not wait zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

KoolKid

Marathons ,if you have nothing constructive to add then don't post here.
First and only warning.

Arthur Spooner

Hi Braka,
Im a bit late joining this!.We are considering installing a reconditioned Oil fired AGA and attaching the snugburner unit. While 30 - 32 litres of Kerosene per week is a considerable improvement on your situation pre snugburner (54/55 litres per week) that still works out at close to €40 per week at current oil prices, which isnt insignificant considering that it is for cooking and space heating in the living areas only. Just wondering how many hours per day do you have your AGA on for that uses 30/32 litres per week? Also is your Aga a 2 door or 4 door? .Thanks.

braka

Arthur Spooner wrote: »

Hi Braka,
Im a bit late joining this!.We are considering installing a reconditioned Oil fired AGA and attaching the snugburner unit. While 30 - 32 litres of Kerosene per week is a considerable improvement on your situation pre snugburner (54/55 litres per week) that still works out at close to €40 per week at current oil prices, which isnt insignificant considering that it is for cooking and space heating in the living areas only. Just wondering how many hours per day do you have your AGA on for that uses 30/32 litres per week? Also is your Aga a 2 door or 4 door? .Thanks.

Hi Arthur,
Our Aga is a recondtioned 2 oven Aga.

With the snugburner fitted there is a variable control from 1-10 that you can use to set the oven temperature.
On our snugburner a setting between 7-8 gives an oven temp of approx 200 deg C. 400 deg F and we turn to this setting at 9am each morning.
The Aga heats up to full heat in about 2.5 hrs - 3hrs ( you can decide for yourself when you need the full temp). Normally we turn down the Aga to about 4 at 9pm and this means the Aga will be kept simmering at a low heat but warm enough to boil kettles etc. and dry clothes etc. In reality the temp does not drop to the 4 setting for about 9- 10 hrs and so its simmering nicely for breakfast etc.

I would imagine in Summertime (if we get a summer!) that we won't need it on as much and perhaps not at all on hot days (some hope!) and we won't have to worry about the domestic hot water as the thermodynamic system is looking after that!

I agree its not cheap.....but an Aga has something about it that attracts people and once you get used to it, its hard to think of getting rid of.
A guilty pleasure I suppose....

BTW it might be an idea to start another thread dealing with AGA topics!

Arthur Spooner

Hi Braka,
Thanks for your reply. Good point - I may start another thread on AGA's as I expect to have a few more queries!. Im trying to gauge how many hours per day/week your aga is on to see what amount burns 30 -32 litres of Kerosene per week. It sounds like yours is on a fair bit, albeit at different settings to suit your requirements - although I note that you mentioned previously that it isnt on 24/7. My wife and I both work so during the week we would expect to have it set to come on for a couple of hours each morning and the same in the evenings when we arrive in from work. It will probably be on a bit longer during the weekends. Is this realistic do you think to get the benefits from it?
Also if you dont mind me asking can you recall what you paid to fit the snugburger?Was this recent? Thanks.

Farrgar

I found this thread very helpful

@fuchia did you ever get a chance to upload those spreadsheets?
@braka How was your usage over the xmass?

Here's a thought I had, if these panels work by being colder than the air around it then why not put them in a greenhouse type thing? you could ever put a rad in with it. Or is that just me being dumb?

Thanks again for all the great info, keep it coming:)

braka

Farrgar wrote: »

I found this thread very helpful

@fuchia did you ever get a chance to upload those spreadsheets?
@braka How was your usage over the xmass?

Here's a thought I had, if these panels work by being colder than the air around it then why not put them in a greenhouse type thing? you could ever put a rad in with it. Or is that just me being dumb?

Thanks again for all the great info, keep it coming:)

Hi Farrgar, and all of you awaiting more data..
As promised I have more data for you (total of 30 weeks).

see attached Excel file

As you know we have had a relatively mild winter with it only getting colder in January. Electricity usage on the coldest days has been around 5 units (mostly 3-4) and there has been no shortage of hot water, even during Christmas week when we had all the family home (8 people most of the week)

I have to say that I am very happy with how economical the system has been to date (less than 5euro/week) and it has surpassed my expectations.

Please feel free to comment.

just do it

braka wrote: »

As promised I have more data for you (total of 30 weeks).

I have to say that I am very happy with how economical the system has been to date (less than 5euro/week) and it has surpassed my expectations.

Thanks for the figures braka. I manipulated your graph (apologies but excel is my thing) to give a full years usage and the total annual cost at the current unit price from airtricity comes to €190