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Solar panels are they worth it

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  • 23-02-2006 11:56pm
    #1
    AJL
    Registered Users Posts: 124 ✭✭


    Folks,

    Considering putting in solar panels to heat water in the Summer. Do they pay back in a reasonable amount of time i.e 4-5 years? Would like to hear from somebody who has them installed.


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    #2
    CJhaughey
    Registered Users Posts: 14,907 ✭✭✭✭CJhaughey


    Ask me in 6 months, I have 6.3m2 of solar panels and a 400l tank not commissioned yet.
    also plenty of threads over in green issues.


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    #3
    Builderwoman!
    Registered Users Posts: 578 ✭✭✭Builderwoman!


    You can do the same...ask me in six months...we have just installed 7.5sq metres. Do you mind me asking you CJ was the 400l tank including a buffer tank and is your solar feeding into your heating or just providing hot water? Do you also mind me asking how much approx it cost? We are deliberating on the tank and have to decide next week. Advice welcomed!


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    #4
    CJhaughey
    Registered Users Posts: 14,907 ✭✭✭✭CJhaughey


    The Tank is purely for DHW.
    There is a capability for using the Solar as a feed for the floorheat pipes but I have not utilised this, My installer was here today and he explained that there is a thermostatic pump that will pump hot water through the pipes until the preset minimum temp is reached, ie 45ºc .
    I haven't used this system yet and probably won't unless the house is expensive and hard to heat with the solid fuel burner and the electric UFH.
    The system is around the 5k mark and installation is another 1k or so.
    Any advice from existing Solar owners is to get as big a tank as you can afford/need.
    there is only 3 of us so 400l is probably overkill now, but....


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    #5
    Mothman
    Closed Accounts Posts: 6,498 ✭✭✭Mothman


    AJL wrote:


    Do they pay back in a reasonable amount of time i.e 4-5 years?

    In a word No, not in that timescale. The timescale depends on what source of heating is being replaced. I worked it out before purchasing that financial payback may be as long as 30yrs. This was replacing night rate electricity. Since then electricity prices have nearly doubled, so shortening payback time considerably.

    I got 6m2 flat panel collectors with 300l tank in 1998. It is integrated in my roof which is at 30deg pitch and south facing.

    From about mid-April to well into Sept the immersion is off except for 2-3 nights during cloudy weather. The rest of year the immersion heats the top half, and solar heats the bottom half. A sunny winter day is enough to heat water to 40C.

    Water use is a daily bath, couple showers, washing machine and the other usual washing etc.

    Other thoughts. The pitch of my setup is too low. Now I would probably go with more surface area and pitch it at 60deg or even higher to face the winter sun more.
    I'm near the coast and recieve more sunlight than inland areas. I would consider tubes before flat plates collectors inland and flat plate before tubes near coast. The tubes perform better in overcast conditions. In sunshine the performance is similar.


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