# Does solar water heating make any economic sense?



## eamonn123456 (5 Oct 2008)

This article strongly argues that domestic solar hot water systems do not make economic sense for the householder:

[broken link removed]

If one uses 3500 units of electricity pa on hot water, that's about 630 euro.

If e.g. a solar system costs 5k, then that's 8 years for break even, ignoring running costs, servicing.

I realise that ESB may go up in price over the next few years, but given that the system may only have 5 year warranty, it still doesnt seem to make much sense economically.

The SEI are pushing these big time, but I guess that is in order to get the national carbon footprint down before we get fined into oblivion.

I also think some people want to have these as a green fashion statement.

Can anyone convince me that these really are the way to go for saving money on domestic hot water?


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## Happy_Harry (6 Oct 2008)

I am sharing your sentiments, just got a quote for around 7K. 
Bear in mind that in the winter you will still use traditional ways to get hot water, be it electricity or gas/oil, as the solar power is simply not strong enough in winter to heat your water to the required temperature. 

I have also read articles where it was claimed payback would be as little as 400 euro per annum.... So at present a return on investment of 15 + years doesn't make any economic sense. Same guy who gave me the quote mentioned if I switch my boiler to a high efficiency condensing boiler I could save 20-30% a year on my heating/hot water costs. That would be a saving of 500 euro (with these oil prices) for a less than 1500 euro investment...3 years ROI... Thanks I think I'll go with that then..

I'll get solar panel or other green means of heating when those technologies have matured a bit and recession will have driven down the price or foreign competitors will have entered the market here.


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## bamboozle (6 Oct 2008)

but thats based on current electricity costs which are going to rise, also solar will add to the value of the house.

i'm a believer!


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## ubiquitous (6 Oct 2008)

eamonn123456 said:


> The SEI are pushing these big time, but I guess that is in order to get the national carbon footprint down before we get fined into oblivion.
> 
> I also think some people want to have these as a green fashion statement.



You could say the same about "carbon footprint" measurements in general.



bamboozle said:


> also solar will add to the value of the house.


I wouldn't be so sure, especially if their economic payback is questionable.


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## Hoagy (6 Oct 2008)

bamboozle said:


> i'm a believer!


 
That's what you need to be.

Hardly any of the alternative technologies make sense from a purely economic viewpoint, hence the grants.

It's supposed to be about doing your bit for the planet.


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## bamboozle (6 Oct 2008)

Happy_Harry said:


> I am sharing your sentiments, just got a quote for around 7K.
> Bear in mind that in the winter you will still use traditional ways to get hot water, be it electricity or gas/oil, as the solar power is simply not strong enough in winter to heat your water to the required temperature.
> 
> I have also read articles where it was claimed payback would be as little as 400 euro per annum.... So at present a return on investment of 15 + years doesn't make any economic sense. Same guy who gave me the quote mentioned if I switch my boiler to a high efficiency condensing boiler I could save 20-30% a year on my heating/hot water costs. That would be a saving of 500 euro (with these oil prices) for a less than 1500 euro investment...3 years ROI... Thanks I think I'll go with that then..
> ...


 

for the record the price i got was about 4.5k after the grant, that is getting the solar system through ecologics (no association)


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## eamonn123456 (6 Oct 2008)

Hoagy said:


> Hardly any of the alternative technologies make sense from a purely economic viewpoint, hence the grants.
> 
> It's supposed to be about doing your bit for the planet.



The following comments, while sceptical, are not meant to be disrespectful to anyone else's (probably better informed) opinions.

My thoughts are: if it doesnt make economic sense, then chances are it costs more in embodied energy than it gives back.  Seems like window dressing to give the illusion of lower energy consumption.  Not sure how that helps the planet to be honest.

Also, the price after the grants are considered is still prohibitively high IMO.

Seems so ironic that we have to consume more stuff in order to save the planet.

Am beginning to think that wearing thermals and/or a jumper would be a lower cost but less fashionable way to reduce costs and cut down emissions.

Not convinced that it will add to the value of the house, at least not as much as it costs to put in place - many home improvements don't.

I realise electricity prices will go up, but I would be interested to see the calculations which would justify going ahead with this.


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## theoneill (6 Oct 2008)

4.5K seems rather steep. I’m just wondering what else 4.5k would buy the average homeowner to allow them to increase the insulation and energy efficiency of their home? Personally I would be looking to break even after 4 years (5 tops) I may not be in my home in 10 years and if solar panels don’t really add much to the value of my home then there has been no real benefit (at least to me).


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## PaddyH (6 Oct 2008)

I put solar panels in over 2 years ago and in general am very happy with them. But i believe the current cost are too high. 

The 6 sq metres of solar panels cost me €6000 approx including 300 litre tank and installation. I got a grant of over €1800 - net cost €4200 approx. It was a new build so more than likely I would be buying a tank anyway so let's throw €500 off for that - so real cost was €3700 approx. The panels are south facing so I'm getting the most out of it - If you're panels are not south facing I see no point in putting them up. 

2 of us live in the house and we normally turn on the oil for at least 15 mins a day to try towels etc - But we normally have hot water 24*7 with the solar panels and oil coming on every now and then. 

I would see the critical issue being the insulation of the water tank - however you heat the tank, you need to insure it remains hot for as long as possible. On average our water drops about 1 degree an hour when not being heating by solar or oil.


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## eamonn123456 (6 Oct 2008)

Very interesting!  In general I guess its cheaper to do this as a new build rather than replacement.

What are the running costs of the HW system i.e. pump etc?

Any maintenance / service costs?

How long is the guarantee?

3700 euro would buy 20000 units of electricity, which would heat a lot of water for two people.

I guess if unit price for electicity goes up enough, and the system lasts long enough, and the running costs are low enough, and the cost for supplementing the supply on bad days is low enough, then it makes sense.

Otherwise, 3700 euro in a bank account over the same term (i know, i know... ;-) ) might be a better option.


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## PaddyH (6 Oct 2008)

New Build Vs Replacement - No Grant available for new build currently - so probably cheaper to install panels on an older house at the moment!

Not sure of the exact running costs - pump uses some electricity - but very little in my opinion - as a side note we have 2 power showers and 1 electric one - Never ever use electric -always use power showers as we always have enough hot water. There was an interesting debate on here recently and I think the general agreement was that Oil is nearly always cheaper than electricity for heating water. Friends of ours always use an electric shower and we have similiar houses - yet their ESB bill is almost €30 a month higher

My opinion would be that a condensing Oil Boiler will heat water more efficiently than an immersion. And obviously important to have a well insulated tank to keep water hot for as long as possible

At a cost of €3700 I think it's worth it - not going to make money - but won't lose alot either - But if the outlay is 5-6K, I wouldn't do it.


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## LouisCribben (20 Oct 2008)

I was researching the viability of solar recently on the internet.

The bottom line is that for every square meter of solar panel you have, it might generate 1 kilowatt hour of energy per day on average. Ireland is cloudy a lot of the time, so you'd hardly get more than 1kw/h per square meter.

In other words, every square meter of panel might save you 1 kilowatt hour of electricity every day.

I live in the UK at the moment, 1 kw/hour costs me 12p (in Ireland it's maybe 16 cents.

Every square meter of Solar panel will save you 1 euro a week on electricity (compared to heating your water with electricity).

The guys who sell and install the panels won't tell you the real facts, i.e. from an economic perspective, installing solar panels does not make sense.

It makes sense from a green/feel good point of view, it's pleasing to think that the water falling on you from your shower is partly heated from the sun, but you are not saving money by doing so.


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## sfag (20 Oct 2008)

Have been stating for a long time that it makes no sense. In the summer my hot water bill is a euro a day. No solar panel is gonna improve on that. I fear there are a lot of green white elephants out there.


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## Chief Seamus (20 Oct 2008)

I'm renting a house with solar water heating right now.
I saw no discernable difference in my ESB bill over the summer (that could be because the sun didn't shine).
What needs to be looked at is the cost of running the things. There is a pump circulating the fluid from the panels to the hot water tank, this pump seems to be running all the time during the day. It's a 75w pump so if it's running for 16 hours that is the same as paying for a 1000w element to be on for an hour and 12 minutes. I don't know what the standard immersion heater wattage is but half an hour heats a lot of water.

also with the solar things, unless you have a very hot day the day before you will need 'assistance' (oil,gas,esb) to have enough hot water for a shower in the morning the next day


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## sydthebeat (20 Oct 2008)

moral of the story, the theorys sound, the practise is flawed...


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## PaddyH (20 Oct 2008)

unfortunately there are good and bad implementations of solar panels - I have mine 2 years now and the pump only runs when it needs to - not 16 hours a day - also plenty hot water the following morning - even average day beforehand - all down to insulation on the tank - i will take time to for the panels to pay off for themselves - but there are significant savings to be made with the correct implementation of solar panels


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## Ned_ie (20 Oct 2008)

Paddy H - what system and who did you go with for your panels?

Thanks


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## jackswift (20 Oct 2008)

Why would anyone need a tank of hot water during the summer anyway? A shower heats water as it comes out dishwashers, washing machines heat water.


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## extopia (20 Oct 2008)

jackswift said:


> Why would anyone need a tank of hot water during the summer anyway?



Huh? Do you ever wash your hands, Jack?


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## jackswift (20 Oct 2008)

extopia said:


> Huh? Do you ever wash your hands, Jack?


 Yes with plenty cold water. Why would you need a tank of warm water during the summer to wash your hands?


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## aircobra19 (20 Oct 2008)

jackswift said:


> Why would anyone need a tank of hot water during the summer anyway? A shower heats water as it comes out dishwashers, washing machines heat water.


 
You might be hand washing dishes, washing babies, cleaning a range of things, and its alot easier in hot water than cold. Maybe having a bath to help with aches and pains, or just because you want to. You might like washing in cold water, but I'd guess you are in the minority.


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## extopia (20 Oct 2008)

Maybe not a whole tank, but certainly some. And yes, I prefer to wash my hands with hot water.


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## PaddyH (21 Oct 2008)

I guess the point is if you have a full tank of hot water and 2-4 people in the house, you will save alot of money compared to 2-4 people using an electric shower. Electric showers are inefficient - i guess it depends on the number of people in the house and how often you take showers - but a recent discussion on this forum proved that heating water with oil (no matter the price) would work out cheaper than using electricity. 

As regards my solar panels, I used a company in Macroom, Co. Cork - Solaris Energy. 6SQ metres of German made Flat panels built into roof with a 300 litre tank. On average water drops about 1 degree an hour during the night etc - so it's often 60 degrees at 10pm and 50 degrees at 8am the following morning - more than enough for several showers


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## Optimistic (21 Oct 2008)

We also used this company in Macroom, and have found them totally unsatisfactory in their back up. No response to phone calls or emails when the system looses pressure etc. So we could not recommend them as a reputable company to deal with.  

As this post seems to indicate, the cost of solar installations is way to expensive in Ireland  to warrant installation except on an green basis. Our tanks looses about the same overnight. WOuld we install solar again if we were at the beginning of the process? NO as pay back is to long. optimistic



PaddyH said:


> I guess the point is if you have a full tank of hot water and 2-4 people in the house, you will save alot of money compared to 2-4 people using an electric shower. Electric showers are inefficient - i guess it depends on the number of people in the house and how often you take showers - but a recent discussion on this forum proved that heating water with oil (no matter the price) would work out cheaper than using electricity.
> 
> As regards my solar panels, I used a company in Macroom, Co. Cork - Solaris Energy. 6SQ metres of German made Flat panels built into roof with a 300 litre tank. On average water drops about 1 degree an hour during the night etc - so it's often 60 degrees at 10pm and 50 degrees at 8am the following morning - more than enough for several showers


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## DavyJones (21 Oct 2008)

If I were to build a house tomorrow I would not fit solar panels. However I would make allowances for them to be fitted in the future I.E run pipe work and fit a cylinder with extra coil. 

I have been to a few courses on the subject and with all honesty the technology used in the actual solar panel coulld have been something you would have seen in De Vinci's handbook

. I feel since they have become more popular, companies will spend more and more money on them. It's a bit like buying a PC five years ago, the same PC is now nearly obsolete. 

In the next five to ten years we will have solar panels good enough to heat the entire home, hot water and heating (by way of buffer tanks) and they will work with any amount of light as opposed to direct sunlight.


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## eamonn123456 (21 Oct 2008)

Thanks for all the responses so far - great stuff.

With respect to those on both sides of the argument, I am more convinced than ever that now is not the time to commit to solar in Ireland.

I am going to focus my efforts and cash on other measures.

Keep the opinions coming!


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## LouisCribben (21 Oct 2008)

DavyJones said:


> In the next five to ten years we will have solar panels good enough to heat the entire home, hot water and heating (by way of buffer tanks) and they will work with any amount of light as opposed to direct sunlight.



A quick glance at the wikipedia article about the sun tells us that the amount of sunlight hitting the earth per square meter on a clear day when the sun is high in the sky is about 1000 watts.  

In Ireland there are clouds quite a lot of the time.

The solar panels today can only capture about 1/5 of the sunlight which the sun has to offer. In the future it might be more.

Even if solar panels are 100% efficient, it will be a big challenge for them to meet all the heating and hot water requirements.


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## DavyJones (21 Oct 2008)

LouisCribben said:


> A quick glance at the wikipedia article about the sun tells us that the amount of sunlight hitting the earth per square meter on a clear day when the sun is high in the sky is about 1000 watts.
> 
> In Ireland there are clouds quite a lot of the time.
> 
> ...




Broaden your scope of research.
 15 years ago they said the internet was impossible. they said you needed a computer the size of a house to do the things laptops do now. Google it, topping up heating systems by means of buffer tanks has already started.  In the near furture clouds will have nothing to do with harvesting solar energy.


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## ubiquitous (21 Oct 2008)

DavyJones said:


> 15 years ago they said the internet was impossible..



The internet is still impossible if you rely on the equipment that was on the market 15 years ago.


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## DavyJones (21 Oct 2008)

ubiquitous said:


> The internet is still impossible if you rely on the equipment that was on the market 15 years ago.




Thats exactly my point, well put.


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## extopia (21 Oct 2008)

ubiquitous said:


> The internet is still impossible if you rely on the equipment that was on the market 15 years ago.



Yes, but that equipment was good enough for the internet of 15 years ago.

Content tends to expand to fill the capacity of the channel.  So the "speed" of the internet tends to stay the same, it's just that the content becomes richer.

To apply the analogy to the world of solar heating, the technology will indeed improve. It can still only produce hot water, but the water will be hotter, or there'll be more of it.

And next year's technology will always be better!


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## eamonn123456 (21 Oct 2008)

Without wanting to extend the analogy too much, unfortunately Moore's Law 

http://en.wikipedia.org/wiki/Moore's_law

does not apply to solar energy systems.

The rate of improvement in the technology is clearly much much slower, given how little it seems to have improved in the last 10 or 20 years.

So, assuming, as I now do, that it is not worth doing just yet, then at this rate of improvement, it will be a long time before it becomes clearly and convincingly worthwhile from an economic point of view.


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## sydthebeat (21 Oct 2008)

eamonn123456 said:


> Without wanting to extend the analogy too much, unfortunately Moore's Law
> 
> http://en.wikipedia.org/wiki/Moore's_law
> 
> ...


 
if you are willing to develop this thecnology yourself, it would be a lot less costly.....

http://www.diydata.com/projects/solarpanel/solar_collector.php


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