solar heating

murphyep

Hi Folks,
Anyone out there using solar panels to heat their house?
Have a supplier calling today to me to discuss this..
He has told me that he can get it to heat 90% of my new build.

Anyone have any good/bad experiences with this?

Regards,
Eddie X5913

biko

Did he give you any details?
Type? How much output they would give etcetera?

murphyep

nothing yet,
Just told me over the phone that they were swiss made and a rough cost of 4800 euro for the panels.
The tank will be an extra cost.

Eddie

Evergreen

How is he planning to heat your house? Radiators, under floor or hot air?

The big question that you have to ask yourself is what are you going to do with all of the excess heat generated in the Summer? To genertae enough heat for you house in the winter will require a lot of panels to make up for the low radiation in the winter. These same panels will generate huge amounts of heat in the summer - fine if you have a swimming pool.

Just a thought

sundodger5

i was told the same by my installer. it just aint true.
I have ^ panels with an aperture size of around 10m2 a 1500l buffer tank with an oil "backup".
i was told i would not need the oil hardly at all and that a days sunshine would heat the house for 2 days.
my experience is a far cry from the claims.

Gurgle

murphyep wrote: »

Hi Folks,
Anyone out there using solar panels to heat their house?
Have a supplier calling today to me to discuss this..
He has told me that he can get it to heat 90% of my new build.

This is absolutely, 100%, guaranteed not accurate.
Either you mis-understood what he said, he misread the info he read or he is just lying.

A solar installation can, if correctly surveyed, specced and installed provide 90% of your hot water for showers/baths/washing machine/dishwasher from approx april to october.

IT WILL NOT HEAT YOUR HOUSE

murphyep

Met the solar guy yesterday.

I am putting underfloor heating in my house.
He said that the solar will heat the house during summer, autumn and spring to around 25 degrees(maybe higher). The oil will bring it up the rest of the way.
My house is 3950 square feet in size. I will need 5 evacuated tube panel for this.

I am currently waiting on a price. But judging by the responses, I dont think I'll be going with it!!!

Sundodger5, Can you expand more about the problems you had with this please?

Cheers,
Eddie

quentingargan

Hi Murphyep.

Please believe me, you are being conned:mad:. Those of in this industry who run ethical businesses get sick of this sort of carry-on from double-glazing salesmen, or well meaning people who haven't a clue.

Solar space heating generally doesn't work very well in Ireland. It was developed in countries like Austria where they get more bright cold days in winter. The attachment gives a comparison between Dublin and Austria month by month. In summer they have much the same as we do, and in winter they have double our December / January energy.

Even in Austria, the system works best on houses that are poorly insulated. The better insulated a house is, the shorter its heating season, and this confines the heating season to those months when solar is contributing the least.

If you already have a large buffer tank for some other reason (e.g. a log gassifying stove) then you may get some benefit from putting in more panels and you will get a number of days each year when the system will heat your house, and it will carry your water heating through the cloudy days, but please don't waste your money putting in a buffer tank for this clown.

Either he is lying, or he doesn't know what he is doing. Either way, you're going to be the loser. Q

murphyep

Thanks Quentin,

I'll stay away from it. Please send me more details on the course.

I am basically looking for an efficient way to heat my house.
I dont have the room for geothermal..
air-to-water might be an option or pellets

Thanks again,
Eddie

quentingargan

Hi Murphy, Replied by PM. Quentin

muffler

quentingargan wrote: »

Hi Murphy, Replied by PM. Quentin

Why would you do that?

pool fan

i found this on another solar site:

Solar energy can also be used for space heating in conjunction with low temperature applications such as under floor heating systems. If correctly sized, the solar system can produce up to 40% of the annual heating load as well as producing 60% - 70% of the hot water load.


Would those figures be accurate?

quentingargan

Passing on details by PM. I am happy to put that up here, but thought that was rather blatent advertising? Q

muffler

Id rather you didnt refer to any course either on this forum or by PM.

Cheers.

quentingargan

pool fan wrote: »

i found this on another solar site:

Solar energy can also be used for space heating in conjunction with low temperature applications such as under floor heating systems. If correctly sized, the solar system can produce up to 40% of the annual heating load as well as producing 60% - 70% of the hot water load.


Would those figures be accurate?

Yes - in another country. But solar space heating would never provide 40% of annual heating load in Ireland unless a house needs to be heated in the summertime.

rayh

murphyep wrote: »

Hi Folks,
Anyone out there using solar panels to heat their house?
Have a supplier calling today to me to discuss this..
He has told me that he can get it to heat 90% of my new build.

Anyone have any good/bad experiences with this?

Regards,
Eddie X5913

Hi Murphep, can I put another view to you.
As you are aware this thread and other solar threads are dominated by a number of commercial contributors who appear to have drawn a fence around 3 panels + 300 Litre tanks & less than 40% space heating systems as the sole right of the solar contribution, however I must complement some of their technical contributions.

The drivers to the above configurations are current economic factors and I take the view that we need to look at this issue in the longer term and I say this from having recently coordinated a CO2 and Energy Minimisation project on 11 existing dwellings of which 7 had solar water heating systems installed.

As a society we have to become carbon neutral at some time in the future and we can approach this in three ways (1) One Step process where we make all the necessary changes in one go. (2) The Ladder process where we make a series of small successive changes or (3) a combination of 1 & 2.

This significance of this issue became very clear to me in the above project where costs per house varied from €5k up to over €90k. The lower expenditures generally provided the best cost savings against current economic criteria, however they are now likely to have placed a barrier to moving to the next step from both a technical and economic perspective.

Therefore, from my own experience of having installed a solar/biomass space heating system, of which the solar is achieving over 150% of the above guidelines. A system that may not be economic in today’s terms, but has enabled me to reduce my carbon load of nearly 14 Tonne per year to over 4 Tonne and only now requires me to replace my electricity and gas cooking emissions to reach the ultimate goal.

quentingargan

Hi Rayh.

Well done on your approach to your own house. What size solar are you using, and do you have any info on the contribution it has made to space heating?

Just to clear the air on commercial contributors, yes - I am involved in a solar water heating business, but nowadays my main work is with domestic wind turbines. I also lecture on solar water heating at CIT and other venues which is where most of my interest in the topic comes from.

If those of us on the forum were really commercial, we would jump at the chance at selling 10 sq m instead of 6. Thankfully most of the commercial contributors to this forum are ethical and really believe in their work - for some of us, our work is our hobby and vice versa.

If I thought solar could make a serious contribution to space heating, I would go for it, but really the low hanging fruit in energy saving is insulation. You'd be amazed at the number of houses we have fitted with solar panels where there is totally inadequate attic insulation!

I presume like many of us, you "get it" about peak oil and/or climate change and see a need to conserve energy regardless of payback time at current energy prices. However, there are usually better options than solar thermal in Ireland. On a new house, passive is now possible. On existing houses look to the new grants for retrofitting insulation, double glazing, HRV, whatever. For space heating, I would argue that they all come in way ahead of solar both in terms of the embodied energy of the system itself and in terms of cost.

If you have access to firewood, log gassifying stoves are, to my mind, the business, and as I said before, if that gives you a 1500L cylinder, then by all means plug a few more panels into it. But few houses have space for a 1.5tonne cylinder. Q

rayh

Hi Quentin,
Firstly let me once again complement you and others which you loosely call “commercials” on the contributions to this forum.

The purpose of my post was to place another option as I interpreted the considerations for a system of a life expectancy of about 30 years as very closely resembling the current economic models. For example the current economic model would have had little relevance 30 years ago and will probably have less in 30 years time and or over a very small portion of the life expectancy of a solar water heating systems. While you have outlined that you are not principally a “commercial” unit, it is likely by your involvement in this business, that your views are somewhat influenced by current commercial values.

As I outlined in my previous post and based on my experiences on the coal face of this area, I see the likelihood of future challenges been inhibited by some very short term commercial considerations.

With respect to your query on the monitoring of my system. I have in place 6 data loggers throughout the dwelling (5 internal & 1 external) recording temperature at 5 minute intervals since February 2007 (1.6M readings) and I have been recoding all energy inputs(albeit at a lower frequency) both before and after upgrade. Would you like a number crunching exercise?

Rayh

soldsold

quentingargan wrote: »

Yes - in another country. But solar space heating would never provide 40% of annual heating load in Ireland unless a house needs to be heated in the summertime.

What are all of your views on using low temp solar water (say 30 degrees thats no use for hot water heating) in the heating season to help supplement MHRV heating?

The idea of it seems to make sense to me, but the view seems to be that it wont help UFH much so is it also the case that it wont help MHRV much?

S.

quentingargan

rayh wrote: »

I have been recoding all energy inputs(albeit at a lower frequency) both before and after upgrade. Would you like a number crunching exercise?

Rayh

Eek! Up to my tonsils on a few projects at the moment, but I would be interested to see the solar inputs, particularly over the winter months. I have to be open to having my mind changed by data which proves me wrong.

Soldsold, the the lower the temperature, then the more efficiently a panel will operate. There are two factors - its ability to absorb light and turn it into heat, and the heat lost through the panel and pipework.

In a flatplate particularly, a large difference between the fluid temperatue and the air temperature causes high heat loss, so at 30 degrees or so, there is a better chance of retaining whatever heat you have collected. Tubes are less affected by the fluid temperature as they are better insulated.

However, there just isn't that much heat to collect. Both systems have low enough efficiency when daylight falls below 400 watts per sq m (see attached jpeg). In winter conditions, according to this graph, with fluid 30 degrees hotter than the surrounding air, tubes will be about 70% efficient, and plates about 60%. There will be further heat loss in the pipework.

Earlier I posted the typical solar energy in Dublin and Austria. In Dublin, the average over 6 winter months is 1.135KwHr per sqm per day. If you have 10 sq m, you get 70% of 11.3Kw hrs is 7.91 kw hrs per day. But there are heat losses in the pipework, pumps and so forth. Lets say optimistically 6kw hrs per day. At 7c per kw hr for oil or gas, and less than that for pellets, that is 42c per day. €76 per year.

I think there is lower hanging fruit out there... Q

soldsold

soldsold wrote: »

What are all of your views on using low temp solar water (say 30 degrees thats no use for hot water heating) in the heating season to help supplement MHRV heating?

The idea of it seems to make sense to me, but the view seems to be that it wont help UFH much so is it also the case that it wont help MHRV much?

S.

My UFH system runs at about 35C so If I had an extremly large array 20m+ and a large buffer tank 2000 litres or so, then I expect that the system could supplement the boiler on a sunny winters day.

One thing to consider with UFH is that there is a large volume of water in the pipes easily a couple of hundred litres, so it won't take long to discharge the heat out of the tank.

soldsold

Thanks for the honest replies and for putting the € numbers up. It certainly looks like the money would be better spent on insulation and airtightness alright.

Alexandr

For Ireland I most suits wind energy generators , but it also works only for big size generators on the coast line.
About solar panels. It's absolutely have no sence for heating in winter. And I do believe, you need heating especialy during cold winter nights. As you can imagine, days in winter are shorter, what means much less energy. And for sure you don't need lots of heating during hot summer days.
Yeah, there are some more disadvantages about those panels. Are you ready to clean them every month? Have you asked what size are they? And they are very brekable.
Ok, enough, I would recomend you to install boiler working on wood pellets, or it can be a pellets stove, there are lots of different designs, will heat all your house easily. Green energy with low price, much lower than natural gas, oil or electricity.

sundodger5

as per dolanbaker above a days sunshine around september when you may need the heat on will run the underfloor in my house for around 20/30 mins before the boiler kicks in. actually this is usually for only half the house as it is split between the bedroom and living areas (zoned)
the house is well insulated and only 2 years old.
i was going through around 250l of oil a month in the winter.
now i accept my install is not as good as i would like (long story pm me for details) but it is a long way from heating my house.