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Heating water: gas vs PV panels

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  • 13-11-2020 12:02pm
    #1
    Vaso_81
    Registered Users Posts: 7 ✭


    Apologies if this is in the wrong forum and apologies for my explanation, I'm new to home ownership and feel useless in general.
    I have a quick question about heating water.
    I recently moved into a new build house and the heating system is a gas condensing boiler with 3 channels. So we can separately heat upstairs, downstairs and the water.
    However, we also have PV panels on the roof of the back of the house (west facing).
    So far, we have been heating the water using the gas but someone commented to my partner in passing recently that it must be very cheap to heat our water due to the PV panels.
    Presumably this would involve us heating water with the immersion? This is something we have never bothered with and didn't really consider as we presumed gas would be the cheaper option. We've never even switched on the immersion and we never thought about the PV panels as we don't know much about them in general, they're not even mentioned in the starter pack given to us when we moved into the house.
    Would anyone know what our best option would be for heating water in the cheapest/most efficient way? Is there even an obvious best option? Or would it be a case of trial and error? Apologies if this is a stupid question.


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    #2
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,213 Mod ✭✭✭✭Wearb


    What are your pv panels using their power for at the moment, if mot for the immersion?

    Please follow site and charter rules. "Resistance is futile"



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    #3
    SouthWesterly
    Registered Users Posts: 6,462 ✭✭✭SouthWesterly


    Check out the renewable energy forum for answers.
    Generally you'll never see payback on buying an Eddie. Have you night rate electricity. You could heat the water cheaper that way.
    What size system do you have


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    #4
    Vaso_81
    Registered Users Posts: 7 ✭Vaso_81


    Wearb wrote: »
    What are your pv panels using their power for at the moment, if mot for the immersion?

    Err the honest answer is I don't know. Literally know nothing about these panels other than seeing them sitting on the roof
    SouthWesterly wrote: »
    Check out the renewable energy forum for answers.
    Generally you'll never see payback on buying an Eddie. Have you night rate electricity. You could heat the water cheaper that way.
    What size system do you have

    Thanks, I'll post in the renewables energy forum too. Yes we do have night rate electricity so did wonder if it would be cheaper to heat water that way or to stick with the gas.
    Sorry I don't know about the size, I'll have to check when I get home.


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    #5
    denismc
    Registered Users Posts: 1,399 ✭✭✭denismc


    Tell us how many panels you have on the roof, that will give us some idea of how much energy you are producing, I'm guessing that you have maybe one or 2 panels which won't produce a huge amount.
    Heating your water from gas is going to be more efficient than P.V, you would need to install a diverter to divert any electricity into your immersion, these typically cost 500 euro+.


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    #6
    Vaso_81
    Registered Users Posts: 7 ✭Vaso_81


    denismc wrote: »
    Tell us how many panels you have on the roof, that will give us some idea of how much energy you are producing, I'm guessing that you have maybe one or 2 panels which won't produce a huge amount.
    Heating your water from gas is going to be more efficient than P.V, you would need to install a diverter to divert any electricity into your immersion, these typically cost 500 euro+.

    It's 4 panels.
    Ah ok, interesting, thanks for your response.


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    #7
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,213 Mod ✭✭✭✭Wearb


    denismc wrote: »
    Tell us how many panels you have on the roof, that will give us some idea of how much energy you are producing, I'm guessing that you have maybe one or 2 panels which won't produce a huge amount.
    Heating your water from gas is going to be more efficient than P.V, you would need to install a diverter to divert any electricity into your immersion, these typically cost 500 euro+.
    What it the default output from/to PV panels, if not wired up to immersion?

    Please follow site and charter rules. "Resistance is futile"



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    #8
    SouthWesterly
    Registered Users Posts: 6,462 ✭✭✭SouthWesterly


    Vaso_81 wrote: »
    It's 4 panels.
    Ah ok, interesting, thanks for your response.

    With only 4 panels there's no reason to be looking for hot water from them as well. They probably are just enough to provide for some of your electricity usage.


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    #9
    denismc
    Registered Users Posts: 1,399 ✭✭✭denismc


    Depending on the age of the panels, they could have an output of 220-300W each meaning you are producing approx 900-1200w in ideal conditions, so in reality all they are doing is reducing the background load on your house.


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    #10
    Vaso_81
    Registered Users Posts: 7 ✭Vaso_81


    SouthWesterly wrote: »
    With only 4 panels there's no reason to be looking for hot water from them as well. They probably are just enough to provide for some of your electricity usage.
    denismc wrote: »
    Depending on the age of the panels, they could have an output of 220-300W each meaning you are producing approx 900-1200w in ideal conditions, so in reality all they are doing is reducing the background load on your house.

    Thanks a million guys, that's exactly the kind of basic information I was looking for.


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    #11
    monseiur
    Registered Users Posts: 1,210 ✭✭✭monseiur


    Not exactly answering your question but.....
    Builders/developers are fitting these basic panels just to comply with part L of building regulations. Technically they're complying with the word of the law...but maybe not the spirit of the law. The whole thing was a sop to the green lobby.
    The fact is that these two panels do more damage to the environment from manufacturing to transport to installation etc. than they'll ever save by the miniscule energy they'll produce, and replacement date will arrive years before the 'notional' pay back date.
    Due to our northern latitude we don't get enough hours of sunshine to make a few panels on a roof economical or environmentally friendly...but try convincing the delusional greens !


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    #12
    Testacalda
    Registered Users Posts: 463 ✭✭Testacalda


    Vaso_81 wrote: »
    but someone commented to my partner in passing recently that it must be very cheap to heat our water due to the PV panels.

    I know you questions have been answered, but this someone is hardly mistaking Photovoltaic Panels for Solar Collectors are they?


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    #13
    corkgsxr
    Registered Users Posts: 3,404 ✭✭✭corkgsxr


    monseiur wrote: »
    Not exactly answering your question but.....
    Builders/developers are fitting these basic panels just to comply with part L of building regulations. Technically they're complying with the word of the law...but maybe not the spirit of the law. The whole thing was a sop to the green lobby.
    The fact is that these two panels do more damage to the environment from manufacturing to transport to installation etc. than they'll ever save by the miniscule energy they'll produce, and replacement date will arrive years before the 'notional' pay back date.
    Due to our northern latitude we don't get enough hours of sunshine to make a few panels on a roof economical or environmentally friendly...but try convincing the delusional greens !

    PV panels seem to be very long life.

    My thoughts is instead of trying to save you money by taking one big chunk, you save by taking lots of the small stuff that runs all day. Eg fridge, heating power, chargers etc.

    Or if we had the newer ESB meters then wind back your bill


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