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Solar panels

24

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  • Registered Users Posts: 1,691 ✭✭✭fclauson


    also look at the attached


  • Moderators, Home & Garden Moderators Posts: 10,135 Mod ✭✭✭✭BryanF


    fclauson wrote: »
    please don't kid your self - after 15 years tubes, pumps, and anti freeze fluid will all need replacing/repairing - not a total replacement but a majour refurb

    Francis how will the lifespan of your preferred HP compare with the SP?
    what sort of guarantees and assurances have you gotten?
    what's the efficiency and potential maintenance comparison over their lifespans?
    Is it relevant that your SP/fossil v HP comparison is based on a passive house standard distribution?


  • Registered Users Posts: 4,939 ✭✭✭goat2


    i hope to get the tubes, but what is really off putting is the price, too much, i will look to go down the diy route, putting a tank in attic which will be warmed up by the panels, and feeding my hotpress tank off this, that way i will have less to buy, just ordinary inderect tank and change connections around a bit


  • Registered Users Posts: 2,820 ✭✭✭MicktheMan


    fclauson wrote: »


    Can you share the maths - please


    kWh price increasing at 12% per annum, 60% of annual dhw from solar

    Year ----kWh ----Price/kWh ----Annual dhw cost ----60% saving
    1
    3500 ----0.12
    420
    252
    2
    3500 ----0.13
    470
    282
    3
    3500 ----0.15
    527
    316
    4
    3500 ----0.17
    590
    354
    5
    3500 ----0.19
    661
    397
    . . . . .
    . . . . .
    . . . . .
    14
    3500 ----0.52
    1833
    1100
    15
    3500 ----0.59
    2053
    1232
    Total saving over 15 years 9394

    Note that general inflation has not being taken into account!


  • Registered Users Posts: 1,691 ✭✭✭fclauson


    Mick - you are right - I made a BIG mistake in my maths

    but (tries to recover);)

    fuel prices today assuming oil we should use about 0.085 at say 90%
    http://www.seai.ie/Publications/Statistics_Publications/Fuel_Cost_Comparison/Domestic_Fuel_Costs_Comparison_January_2012_pdf.pdf
    which changes things a bit = €7437 costs after 15 year

    If your system cost €4.5K then thats €2937 saved

    All I was trying to point out is that there are not the BIG immediate savings with solar to be made which people thing
    with a pay back of 11,12,13,14 years depending - its a long term investment


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  • Registered Users Posts: 1,691 ✭✭✭fclauson


    BryanF wrote: »
    Francis how will the lifespan of your preferred HP compare with the SP?
    what sort of guarantees and assurances have you gotten?
    what's the efficiency and potential maintenance comparison over their lifespans?
    Is it relevant that your SP/fossil v HP comparison is based on a passive house standard distribution?

    Brian - basically I don't know - my parents fridge is 20 years old - I had one which failed after 5 - (both use the basic same compressor technology that a HP does)


  • Registered Users Posts: 2,820 ✭✭✭MicktheMan


    fclauson wrote: »
    All I was trying to point out is that there are not the BIG immediate savings with solar to be made which people thing
    with a pay back of 11,12,13,14 years depending - its a long term investment

    I agree ... most people don't have the first clue what it costs them to heat their water or even what is the most efficient method.


  • Closed Accounts Posts: 13,993 ✭✭✭✭recedite


    fclauson wrote: »
    Lets say its 3500 Kwh (thats for a family of 6) ....

    Also, 5000 - 6000 Kwh (units of electricity) is more realistic for a family of 5 people.
    So, 5500*€0.12*0.6*15 years = €5940 even with no fuel inflation.

    Better to pump a few grand into our own green economy, than to be permanently importing dirty fossil fuels from abroad. And if you can save money while you're at it, everyones a winner.


  • Moderators, Home & Garden Moderators Posts: 10,135 Mod ✭✭✭✭BryanF


    fclauson wrote: »
    Brian - basically I don't know - my parents fridge is 20 years old - I had one which failed after 5 - (both use the basic same compressor technology that a HP does)
    fclauson wrote: »
    also look at the attached
    FC, can we see a little more detail on the brake down of the costs here thanks


  • Registered Users Posts: 1,691 ✭✭✭fclauson


    recedite wrote: »
    Also, 5000 - 6000 Kwh (units of electricity) is more realistic for a family of 5 people.
    So, 5500*€0.12*0.6*15 years = €5940 even with no fuel inflation.

    Better to pump a few grand into our own green economy, than to be permanently importing dirty fossil fuels from abroad. And if you can save money while you're at it, everyones a winner.


    6000kWh for just heating the hot water per annum ?


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  • Registered Users Posts: 1,691 ✭✭✭fclauson


    BryanF wrote: »
    FC, can we see a little more detail on the brake down of the costs here thanks

    Sure

    the usage numbers are taken from a combination of DEAP and PHPP - both have their own view on how much energy demand my build will have.

    Using those as a base number I then calculated the costs for each system over 15 years (which was selected for no good reason other than than oil & gas boilers have a life of about that)
    Assumes equal capital outlay (which is a bit skewed because at the low energy demand end of the scale a HP is cheaper to install than SP + Thermal store + Oil or Gas)
    Also remember that as part of this I have to hit part L renewables - because obviosuly the very cheapest from a capital costs perspective would be a cheap and chearful oil boiler on its own.

    given these energy demands then I calculated running costs

    Attached is the spread sheet - just change the YELLOW :) boxes to enter you own deamand figures

    Please do me a favour and publish your results here - so we can do a bit of a public compare


  • Registered Users Posts: 4,748 ✭✭✭Do-more


    recedite wrote: »
    Also, 5000 - 6000 Kwh (units of electricity) is more realistic for a family of 5 people.

    I made an attempt to quantify energy usage for our DHW a few months ago.

    All our DHW is heated by electric immersion. I should have fitted an energy monitor on it last year to get an accurate figure but could only do a guesstimate from our electricity bill.

    Working backwards so that any errors or inaccuracies add to the DHW portion of the bill I figured that for our family of 4 worst case is currently 3000kWhr per year for DHW.

    I was surprised at that myself expecting it to be higher, granted the kids are only 5 & 8 so are not teenagers standing in the shower for 30mins a time!

    invest4deepvalue.com



  • Registered Users Posts: 2,820 ✭✭✭MicktheMan


    recedite wrote: »
    Also, 5000 - 6000 Kwh (units of electricity) is more realistic for a family of 5 people.

    Our dhw is only heated by our non-condensing ch oil boiler (have never used the immersion) and we use between 300 and 320 liters of oil per year to heat the dhw.
    This would tally pretty well with FC's figure for dhw use. There are 5 in our household including 3 teenage girls!
    So the 5-6000 kwh figure is deffo on the high side.


  • Closed Accounts Posts: 3,327 ✭✭✭Merch


    fclauson wrote: »
    Sure

    the usage numbers are taken from a combination of DEAP and PHPP - both have their own view on how much energy demand my build will have.

    Using those as a base number I then calculated the costs for each system over 15 years (which was selected for no good reason other than than oil & gas boilers have a life of about that)
    Assumes equal capital outlay (which is a bit skewed because at the low energy demand end of the scale a HP is cheaper to install than SP + Thermal store + Oil or Gas)
    Also remember that as part of this I have to hit part L renewables - because obviosuly the very cheapest from a capital costs perspective would be a cheap and chearful oil boiler on its own.

    given these energy demands then I calculated running costs

    Attached is the spread sheet - just change the YELLOW :) boxes to enter you own deamand figures

    Please do me a favour and publish your results here - so we can do a bit of a public compare

    Equal capital outlay for HP to Sp based on a new instal maybe?? I cant imagine the capital outlay for a HP, space heating system to be cheaper than any other existing system given the kind of work needed to be done.
    Is the efficiency for the HP given an average across a year as it surely will go up and down through the year? and be different for space and dhw? what is the COP for dhw using HP, thought HP was better for space heating than dhw and better performance on the basis it was run quite continuously at low temp and not on and off, thereby offsetting the gains? unless it is in a 24hour occupied building.
    HP still uses electricity, only, whereas SP offsets the amount of gas/oil used to heat water reducing the consumption. HP only maintains the advantage if the COP can be guaranteed to be between certain values all the time surely?
    Out of curiosity, in the event of a power/pump failure, what fail safe prevents damage to solar thermal (tubes) if the pump doesnt run for the above reasons?


  • Closed Accounts Posts: 13,993 ✭✭✭✭recedite


    MicktheMan wrote: »
    Our dhw is only heated by our non-condensing ch oil boiler (have never used the immersion) and we use between 300 and 320 liters of oil per year to heat the dhw.

    How do you know how much oil went on space heating, and how much on DHW only?


  • Registered Users Posts: 2,820 ✭✭✭MicktheMan


    recedite wrote: »
    How do you know how much oil went on space heating, and how much on DHW only?

    I have 2 hour meters, 1 connected to the space heating pump and the other to the dhw pump. Each hour meter is activated when its pump and burner are energised. I then convert the hours recorded into liters of oil consumed by the boiler jet size / oil pressure. It is quite accurate as oil consumed matches what gets delivered:)


  • Registered Users Posts: 1,691 ✭✭✭fclauson


    Merch wrote: »
    Equal capital outlay for HP to Sp based on a new instal maybe?? I cant imagine the capital outlay for a HP, space heating system to be cheaper than any other existing system given the kind of work needed to be done.
    My maths is comming from the point of a new build
    Is the efficiency for the HP given an average across a year as it surely will go up and down through the year?
    yes - COP is a measurement at a point in time SPF is an average - averages are averages and no manufactuer publishes them

    and be different for space and dhw? what is the COP for dhw using HP, thought HP was better for space heating than dhw and better performance on the basis it was run quite continuously at low temp and not on and off, thereby offsetting the gains?

    there is much debate as to what the COP of h/w is - DEAP uses a number of calcs - but 0.75 of heating COP is consider roughly ok

    HP still uses electricity, only, whereas SP offsets the amount of gas/oil used to heat water reducing the consumption. HP only maintains the advantage if the COP can be guaranteed to be between certain values all the time surely?
    yes - but one can run with averages to get a close approximation
    Out of curiosity, in the event of a power/pump failure, what fail safe prevents damage to solar thermal (tubes) if the pump doesnt run for the above reasons?
    each manufacturer handles this differently - but it has to be handeld some how


  • Registered Users Posts: 1,691 ✭✭✭fclauson


    MicktheMan wrote: »
    I have 2 hour meters, 1 connected to the space heating pump and the other to the dhw pump. Each hour meter is activated when its pump and burner are energised. I then convert the hours recorded into liters of oil consumed by the boiler jet size / oil pressure. It is quite accurate as oil consumed matches what gets delivered:)

    Cool - I think all building should do this - it would get rid of the nonsense of guessing


  • Closed Accounts Posts: 3,327 ✭✭✭Merch


    fclauson wrote: »
    each manufacturer handles this differently - but it has to be handeld some how

    Do you have an idea how it is handled? I was thinking of some battery backup, solar or charged from mains running a seperate pump via a bypass, but I havent seen how it is managed.
    As I am in an existing build I definitely would consider solar evacuated tubes as my best option.

    On a seperate note, is it possible to try and determine your own BER, I googled DEAP but cant find the download for it on the seai website, is it easy to input any data or does it require some practice or specific knowledge?


  • Registered Users Posts: 1,691 ✭✭✭fclauson




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  • Closed Accounts Posts: 3,327 ✭✭✭Merch


    hmm, there's a bit in there, not sure how I might find the U value of windows (double glazed) that were installed more than ten years ago??


  • Registered Users Posts: 1,691 ✭✭✭fclauson


    Merch wrote: »
    hmm, there's a bit in there, not sure how I might find the U value of windows (double glazed) that were installed more than ten years ago??


    page 130 is where to start - and you answer will probably 2.somthing - 2.7 being a good spot to start


  • Registered Users Posts: 127 ✭✭snow mad


    recedite wrote: »
    The worst that can happen is you only save about €350 a year and the panels fall apart after 15 years. In that case, you break even. .

    I DONT KNOW ABOUT YOU BUT MY HEATING BILLS ARE ABOUT 700 A YEAR AND ABOUT 30% OF THIS GOES TO HOT WATER=210. SOLAR PANELS GIVE YOU UP TO 70% OF THIS = 147. AND THESE ARE THE HIGHER % SAVINGS BEING THROWN AROUND. THAT IS A MAXIMUM OF 4410 OVER 30 YEARS THEN TAKE SERVICING OF THIS 150MIN EVERY 4 YEARS=1125

    4410-1125=3285

    BY THESE FIGURES WHICH ARE GENEROUS TO SOLAR THE SYSTEMS ARE HIGHLY OVERPRICE IN THIS COUNTRY AND REALLY HAVE LITTLE HOPE OF PAYING FOR THEMSELVES NEVER MIND SAVING ME MONEY


  • Registered Users Posts: 4 ConorOB


    MicktheMan wrote: »
    I have 2 hour meters, 1 connected to the space heating pump and the other to the dhw pump. Each hour meter is activated when its pump and burner are energised. I then convert the hours recorded into liters of oil consumed by the boiler jet size / oil pressure. It is quite accurate as oil consumed matches what gets delivered:)

    Hi Mick,

    I'm very interested to know the percentage of your home heating oil used on DHW how much this costs. I'd also like to know if you use an immersion for DHW during warmer months when you don't need central heating on.

    Many thanks,

    Conor


  • Registered Users Posts: 2,820 ✭✭✭MicktheMan


    ConorOB wrote: »
    Hi Mick,

    I'm very interested to know the percentage of your home heating oil used on DHW how much this costs.

    A sixth of our oil consumption goes to heating the dhw; cost in the region of 250 per annum.
    ConorOB wrote: »
    I'd also like to know if you use an immersion for DHW during warmer months when you don't need central heating on.

    Many thanks,

    Conor

    We dont use an immersion. The boiler setup / control is designed to be able to only heat the dhw if needed (i.e. outside of the heating season).


  • Registered Users Posts: 308 ✭✭clint_eastman


    MicktheMan wrote: »
    I have 2 hour meters, 1 connected to the space heating pump and the other to the dhw pump. Each hour meter is activated when its pump and burner are energised. I then convert the hours recorded into liters of oil consumed by the boiler jet size / oil pressure. It is quite accurate as oil consumed matches what gets delivered:)

    Would you be able to send me a PM with some details on these meters, I'd be interested in setting these up aswell...


  • Registered Users Posts: 2,820 ✭✭✭MicktheMan


    Would you be able to send me a PM with some details on these meters, I'd be interested in setting these up aswell...

    No need for a pm. Google "hour meter" or go to a good electrical wholesaler. They are widely available and cheap as chips.
    How you install it will depend on your boiler/distribution/controls but the simplest would be to link it across the burner power and then monitor it, say once a day when the ch is not being used. Then average the daily usage over say a month to get average dhw use.
    You will need to know your nozzle size, usually expressed in US gallons per hour and have your oil pressure checked. This will then need to be converted to liters per hour.

    For instance if your nozzle size is .75 Us gallons per hour and oil pressure is right then this equates to 2.84 liter/hour. If average boiler firing for dhw is 0.4 hours then your average oil use for dhw is 0.4x2.84 = 1.14 liters per day.


  • Closed Accounts Posts: 305 ✭✭richiek67


    Well, I explained all the things in detail to my Wife and she began to see sense. To give you an idea of one such worry she had.....this is a good one, and I dont mean to be laughing behind her back .....
    She felt all the plumbing had to be disturbed etc, i told her the only thing that gets moved etc is the joints on the existing tank, nothing else. She was under the impression with a new house that plumbing , in terms of heating water and immersion, is all different, given our house is 30 years or so old. I had to explain that the way a house is plumbed has not changed in 60 years, principals are still exactly the same .... and new houses have plumbing done in exactly the same way...
    ( god its hard when women are clueless technically )

    Anyway, now I'm not even sure if I want to go ahead after all my research. The fear is, in 2 years from now the systems will be better by 20% in terms of efficiency, its like buying a computer, 6 months don't the road there's another on the market twice the speed.! June is my target when everything is quiet. No school runs etc. The guy in AEI will probably put the price up. He's ringing me already. Is it still slow in this area does anyone know.

    O, another thing my wife wanted to know, and to be fair its a valid point, WHY ISENT EVERYONE GETTING THIS DONE?? Is it not a win win situation, is it money??

    IS IT WORTH THE HASSLE??? Now that we have OIL off cork...!!! lol

    Cheers

    Rich


  • Registered Users Posts: 47 refco


    To work out cost of heating water tank on E.S.B.
    Its worth noting i dont sell or work with solar so my temperatures are based on fiction not fact

    litres *4.18 * temp = ans /3600=kwh * esb rate
    example incoming water at 10 degrees and heating 300 litre tank to 80 degrees you need to add 70 degrees heat
    300*4.18*70=87780/3600=24.38*.19=3.09 * 365 = 1127.85 euro per annum
    if your have solar assuming a year round average of 30 degree input you have to add 40 degrees heat to tank
    incoming waer 10 plus solar input of 30 = 40+40=80
    300 * 4.18 * 30=37620/3600=10.45*.19=1.98 *365= 722.70 euro per annum

    Giving a saving of 1.11 per heated tank if heated every day annual saving of 405.15
    average of 40 was figure pulled out of the air just for example and .19 esb is unit per kw inc vat i think can be replaced with oil or gas per kw cost


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  • Closed Accounts Posts: 13,993 ✭✭✭✭recedite


    refco wrote: »
    24.38*.19=3.09
    small mistake in the maths; 24.38*.19= 4.63

    BTW that 24.38 KW/hr per day is equal to 8900 KW/hr per year for DHW usage.
    But then if you emptied a 300 litre cylinder every day, you would be using more than the average home would use.

    A simpler way to look at the solar input for this scenario is;
    300*30*4.18/3600*0.19= €1.99 per day or €725 per annum


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