# Solar collectors and photovolatic this year



## alert (4 Sep 2007)

Hi guys,

I am quite interested in investing in solar panels for water heating, I hear they're very good. However, considering the prices and number of years for return on investment involved, I would appreciate if anyone who has either water-heater or photo-voltaic systems could let me know how the awful summer we had affected their response?

Also, I was surprised to see a news article on the BBC1 Breakfast programme, this morning, concerning people who live "off-grid" whereby one house-holder derided his two wind-turbines in favour of his photo-voltaic system for energy generation, I had thought that photovoltaic was not worth the effort - Has the technology improved recently?

Thanks,

ALERT.


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## MulberrySt (5 Sep 2007)

Hi there,
I have had solar collectors installed in my new build, however they are not up and running yet. The plan is for them to heat water only. But on reflection, they are quite an expensive outlay and while the grant is a help, proportionately speaking, it's a token gesture IMO. Anyway, bottom line, if I was to do it again, given the above and the fact that it's relatively cheap to heat water, I would give much more consideration to a space heating element in the system.
Unfortunately my knowledge in this regard is fairly limited.
Good luck


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## homer911 (25 Sep 2007)

*Re: Solar collectors and photovoltaic this year*

I has Solar Collectors installed about this time last year.  I'd recommend it, but make sure you use the more expensive vacuum collectors rather than the flat panel type system.  Flat panels are fine for high ambient air temperature but lousy for Irish Weather.  Motivation was a number of reasons - Cost of Gas, impact on environment, available grants, ability to completely turn off the gas boiler in summer etc.

One of the biggest elements of the cost was actually the new emmersion tank - we replaced a 120 lt tank with a 300 litre tank for a family of 5.  My collectors face due south although the afternoon sun is clearly the hottest.  Performance this year has been reasonably consistent with the temperature typically between 50-55C in the tank at the "upper" temp recorder which is about half way up the tank.  On a good day this would rise to 60 degrees.  35C provides a good hot shower!  The best day in 2007 (South County Dublin) was Good Friday when it hit 85C - the overheat system actually kicked in to spill the surplus heat into the attic.

The grant application process is a pain!  You have to choose an installer, get a quote, submit your application, wait for approval, pay your deposit, wait for your contractor to have room in his schedule and when work is completed and commissioning cert is provided, along with proof of payment, you can finally apply for refund.  Cost for me was around €4k-€4.5k after grant.  installer was pretty good, but i got short shrift over installation when previous jobs run over - they are at the mercy of the weather and if its too windy, it delays things.  Everything running to schedule it takes about 3 days to install

Go for it!  You'll spend the first month after installation pressing buttons on the control panel to see how good the system is!  Even in winter, on a sunny day the system will pre-heat your water to about 30C, which is a big improvement on the water coming in at about 5C.


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## ninsaga (25 Sep 2007)

homer911 -which solar heater system did you choose?


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## peter11 (25 Sep 2007)

installed solar panels this year, my wife didnt approve initially but since they were installed she is delighted.  Even though summer was not great I had hot water all summer.  Brillant and I would not look back.  Be careful on pricing.  If you need help shout ok


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## Silvergirl (25 Sep 2007)

Anyone have the solar panels from Velux?

We are thinking of installing these and are after getting a quote of approx 8.5K for 6 sqm.

They look just like a velux window which is good as the front of our house is due South, however it's a bit of a price difference for aesthetics.

Other panels have been quoted at approx 6k - all excl of grant.

Any opinions?


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## bcol1 (26 Sep 2007)

We installed solar collectors on our new build also (vacuum tube panel). Also 300 litre water tank. We had the heating off since end March, so were relying on the solar panels alone for heating water for the past 6 months and we always had more than enough, and more than hot enough for showers etc. I too was a bit reluctant about installing them due to the initial outlay and long period of return on investment but i am glad we did it. The convenience alone of not having to worry about turning on an imersion all the time is great. We used Glas to supply and intall - www.glas.ie and were very happy with the service.


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## hotlips (26 Sep 2007)

Like bcol1, we just had collectors installed by Glas. We've only had them a few weeks and we were getting all of our hot water from them before it suddenly turned cold and we have the heating on now anyway.

We don't have a south facing roof so we have collectors on both the east and west. So, our system is a bit more complicated that one collector on a south-facing roof. Glas were good to deal with during the installation process and came back a few times to make sure everything was configured ok. 

(I have no connection with Glas, other than being a customer.)


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## homer911 (26 Sep 2007)

ninsaga said:


> homer911 -which solar heater system did you choose?


 
The details I can lay my hands on are:

RESOL DeltaSol Controller
RESOL FlowCon A pump and mounting
RESOL VA32 Motorised Valves

I cant find the details of the collectors but they could have been from Thermotechs (http://www.thermotechs.com)


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## homer911 (26 Sep 2007)

Silvergirl said:


> Anyone have the solar panels from Velux?
> 
> We are thinking of installing these and are after getting a quote of approx 8.5K for 6 sqm.
> 
> ...


 
These velux collectors look like flat panels and I'd guess thats why 6 sq mtres is proposed - you wont get much, if anything, out of them in winter.  Because they are less efficient, you need more of them - you get a bigger grant though, the grant scheme seems to encourage inefficiency!


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## craggel (26 Sep 2007)

homer911 said:


> These velux collectors look like flat panels and I'd guess thats why 6 sq mtres is proposed - you wont get much, if anything, out of them in winter. Because they are less efficient, you need more of them - you get a bigger grant though, the grant scheme seems to encourage inefficiency!


 
[broken link removed]


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## Armada (26 Sep 2007)

Silvergirl said:


> Anyone have the solar panels from Velux?
> 
> We are thinking of installing these and are after getting a quote of approx 8.5K for 6 sqm.


 


Hi Silvergirl...

Where did you actually get the price for the Velux? Are they in stock in stores now, do you know?


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## hotlips (27 Sep 2007)

Yorky said:


> Be careful about solar water heating. Heating the water is all well and good but can you actually use it? If you have an electric shower, it is 'cold fill'. The same goes for a dishwasher & washing machine. So, the only way of using the hot water is through the taps or a mixer-valve shower.
> 
> I think solar power has it's place in electricity generation and space heating but not in water heating, unless appliances revert back to 'hot fill'.


 
We have no electric showers. All the showers in the house use the hot water from the cylinder. Our Miele dishwasher and washing machine can be connected to either cold or hot water supplies.


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## homer911 (27 Sep 2007)

Craggel makes a good point, but I dont agree with this website owner recommending you but a woolly jumper instead.

Anyway for the benefit of ninsaga, the collectors are got are from Navitron who claim an efficiency of almost 80%
[broken link removed]


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## Mrs Aol (28 Sep 2007)

We have 12 sq m of solar panels which gives us hot water but even better runs our heating. We have a wood pellet stove with integral boiler as back up but so far it has rarely been on. This said it's very early days yet as we only moved in at the end of June! It's an eco house designed with passive principles, it has very high insulation and air tightness so obviously this makes a difference. 

I often hear people give the impression that solar panel aren't suitable for heat so I just wanted to mention that in some cases they can be.


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## elefantfresh (28 Sep 2007)

Mrs Aol - are you saying that you are heating your house entirely (so far) with just solar panels heating the rads? Thats nuts! If its that good why is everyone not at this? I'd love to see a report from you after the winter to see is it really that good. Free heat has to be good. Like you said, the house is uber insulated but even still....


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## sas (28 Sep 2007)

Mrs Aol said:


> We have 12 sq m of solar panels which gives us hot water but even better runs our heating. We have a wood pellet stove with integral boiler as back up but so far it has rarely been on. This said it's very early days yet as we only moved in at the end of June!
> I often hear people give the impression that solar panel aren't suitable for heat so I just wanted to mention that in some cases they can be.


 
I live in a shockingly badly built estate house with 0 sq m of solar panels which run our heating. We have an oil boiler as back up but so far its barely been on. In fairness, we've only been renting it since July. 

No offence but I think you're singing your systems praises for space heating a tad early!


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## Mrs Aol (28 Sep 2007)

Hey I know that only time will tell exactly how the system will preform. Don't have a go at me - I'm not trying to sell anything! If I was at the stage of deciding a heating system I'd find it interesting that solar panels can be used so I'm just mentioning it really. We are carefully monitoring the system so if I'm still popping in to these boards I will post the results after the winter months. There are some other houses with a similar set up to ours. The 2 I have details on have had good results. One spending 360 euros over a 12 month period and the other only spending 420 over 20 months.


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## bertie1 (29 Sep 2007)

Mrs Aol , 

What type have you got ? 

We have evacuated tubes & have hot water from them with no oil from April to the end of September , turn the oil on last week becuase it got colded at night. 

I am curious to know how they are heating the house as well


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## Startup (2 Oct 2007)

Let me first declare that I sell solar collectors for a living so I could be accused of having an agenda. 

The prinicipal issue with using solar collectors (for heating water, not to be confused with Solar PV) for space heating is that when you most need the heat i.e. in winter at night, there is no sun
Space heating via solar can be achieved via a thermal store i.e. a large cylinder by heating it during the day and discharging thew heat during the evening/night. I'm not even sure that the economics stack up in the average Irish house, because typical insulation levels are so deficient that the discharged heat isn't retained for very long and depletes the store very quickly, otherwise a very large thermal store is required. 

Heating of domestic hot water is a much better proposition. I wouldn't agree with yorkys comments because of the following.
The average person uses about 40-50 litres of hot water per day. Many showers installed today are directly pumped from from the cylinder and the water is mixed through a themostatic valve to 65 degrees C at the cylinder. About 25% (an average) of your annual energy goes on producing hot water most of which is used for showers and baths. Solar gives you about 60% of that 25%. That is a substantial contribution. Bear in mind that based on todays energy costs solar water heating pays for itself in 6-10 years (oil has gone from $80 to $83 a barrel in the last number of weeks) the payback may eventually be even shorter.

What are people being offered for €6000? Does this include the cylinder and installation?


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## sas (2 Oct 2007)

Startup said:


> The prinicipal issue with using solar collectors (for heating water, not to be confused with Solar PV) for space heating is that when you most need the heat i.e. in winter at night, there is no sun


 
Hi,

How much heat (towards space heating) can you realistically expect to get from solar panels in the heart of winter during the limited daylight hours we get? What sort of additional cost in terms in the thermal store etc. would you incur to try and get the benefit from it?

Given that most of us will be incurring that additional cost on the mortgage, you can effectively double whatever you pay over say a 30 year mortgage term. Does it still make financial sense?

SAS


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## Startup (2 Oct 2007)

Hi SAS
The worst winter day only provides 10% of the solar radiation in summer, so in order to heat the same quantity in winter you need a lot more panels than would normally be specified for a 'summer sized' system. The thermal store could be in the order of 1000 litres for domestic space heating. A standard 300 litre stainless steel tank is around €1500 so if you pro rata that you see how the cost starts to stack up. To be honest I haven't done the maths on this solution, but would be happy to talk with anyone who wants to seriously examine it.  The best place to start with something like this is to examine the annual opertion cost of a conventional heasting system. The avergae household spends 50% of the annual energy cost on space heating, so the equation is somewhat different in terms of calculating the cost benefit. I don't quite follow your reference to mortgage repayments. can you elaborate?


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## sas (2 Oct 2007)

Startup said:


> I don't quite follow your reference to mortgage repayments. can you elaborate?


 
My point was that in most cases on new builds the money is borrowed and hence subject to interest. For any mortgage amount initially borrowed you can realistically expect to repay double that over a 30 year term. So if I borrown an additional 3000 euro extra for the thermal store, its really going to cost me 6000 euro by the time I've paid for it.


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## sas (2 Oct 2007)

Startup said:


> The best place to start with something like this is to examine the annual opertion cost of a conventional heasting system.


 
This needs to be taken into account but you couldn't rely on a solar only heating system without some form of back up. So you most likely would end up paying for a conventional system anyways that costs slightly less to run based on the benefit provided by the thermal store.

I take your point though, higher initial installation cost but much lower running costs.


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## Startup (2 Oct 2007)

Sorry, I'm with you now. You're right typical lifetime mortgage repayments I would have put at 1.8 x the original sum borrowed. Remember that a grant of €300 per metre squared of absorber area is payable by SEI for installations limited up to 12 metres squared of panel. This helps to dampen the fiscal blow a little. I am working on a commercial project for a customer at the moment who wants to use solar to contribute to space heating requirments, but I've already warned him that the economics may not make sense.


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## Silvergirl (8 Oct 2007)

Hi Armada,

The quotation is part of our plumbers quotation, I didn't see them on the Velux.ie price list, so I've emailed their enquiries@velux.ie for a price also,

Rgds,


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## towbar (8 Oct 2007)

Startup - is the thermal store the same as the buffer tank thats used with wood pellet boilers?  It is supposed to only lose 1 degree over 24 hours (500l).

We were hoping at some point to add solar to our buffer tank as a secondary heating source.  Even if it didnt heat up the tank fully it would at least reduce the amount of pellets used.

I know even during summer there will be some evenings where the house requires a top up of heat late evening so using solar for only heating water means you still have to have the boiler available. If solar heats our buffer tank during the day to at least 60 that would heat the hot water and provide for a heating top up in the house if required.


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## Silvergirl (15 Oct 2007)

Ok price back from Velux in UK re solar panels: Eur 4400 ex vat for 7.5 sqm

You can download a brochure and price list from 
www.carbon-neutralhomes.ie but they are only available to buy from builders merchants etc not direct.

They are set into the roof like a regular velux roof window.

Anyone had any experience please let me know.

Thanks


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## Startup (29 Oct 2007)

Hi Towbar, I haven't looked at wood pellet systems in detail. I would need to see a specification for the buffer tank. I would doubt the heat loss statistic of 1 degree in 24 hours. This statistic seems to be thrown around by sales people in the heating industry. I can assure you that there are very few tanks on the market that would come close to or achieve this level of heat retention. 
Solar could be used very effectively if sized correctly for your system for summer time contribution. Have you specifcations/schematics of the system that you've installed?





towbar said:


> Startup - is the thermal store the same as the buffer tank thats used with wood pellet boilers? It is supposed to only lose 1 degree over 24 hours (500l).
> 
> We were hoping at some point to add solar to our buffer tank as a secondary heating source. Even if it didnt heat up the tank fully it would at least reduce the amount of pellets used.
> 
> I know even during summer there will be some evenings where the house requires a top up of heat late evening so using solar for only heating water means you still have to have the boiler available. If solar heats our buffer tank during the day to at least 60 that would heat the hot water and provide for a heating top up in the house if required.


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## Mrs Aol (28 Jun 2008)

Hi, I know this is an old thread but I did say I'd come back with info having been in house a year. 

Well our year is up today! We've used 1150kg of pellets. This is to run heating for 2000sqft (I'm here all day with 2 children so it needs to be warm all day) and all hot water for 2 adults and 2 children (including hotwater feeding dishwasher and showers (obviously we don't have electric showers!)).

We have about 12sqmt flat panels.

We reckon we didn't really figure out the best settings to have until about Dec. We were wasting pellets and heat but sorted now and I expect next years total to be lower (maybe by about 2 or 300 but that just a calculated guess on my part).

We're happy with the system the only complaint was that before we completely got the hang of it we were sometimes too hot - especailly when we had visitors - everyone knows now to come in a teeshirt and flipflops all year around!


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