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Type of heating system

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  • #32
    fclauson
    Registered Users, Registered Users 2 Posts: 1,691 ✭✭✭fclauson


    BarneyMc wrote: »
    This is very interesting. Can I ask the following:
    1. Are you saying the PV powers the HP when it's producing electricity, i.e. during daylight hours?
    2. Do you use 'standard electricity' to power the HP after daylight hours?
    3. Can you feed unused electricity back to the grid when you don't need it?
    4. Can the electricity from the PV be used for any domestic use and not just for the HP?
    5. Do you require south facing roof for the PV plates?

    Thanks for any info!

    The approach I have taken is to install enough PV to produce the amount of energy I need to heat and produce h/w for the year. In my case its around the 4200Kwh mark.

    The PV is grid connected so any over production of electricity I ask the ESB (very nicely) to look after for me until I need it. They give me 9c/unit for every unit I push back onto the grid.

    I then programm the HP to
    a) run 11pm-6am when you can purchase electricity at 8c/ unit night rate
    b) to run 10am -> 5pm during which time if its sunny then I can directly use the energy I am producing.

    during 6am -> 10am and from 5pm -> 11pm the system coasts as there is enough thermal mass to not allow the building to drop in temp much less than 0.1 degree most of the time !!

    this set up effectively allows me to use the ESB as an inter seasonal store. During the summer I store up energy and in winter I draw it back again. Even if I am away for two weeks on hols then the ESB will keep storing up that energy (solar thermal does not do this)

    Now obviously if its not sunny during the day then I pay 18c/unit from the grid - and in the midsts of a very cold winter that might happen - the nice thing is that very cold winter days are often clear so you will get solar gain into the building
    On average over a year I believe that my config will roughly give me zero running costs for the HP - and that is true for the next 15 or 20 years until some component needs replacing (pumps probably being the first item to fail)

    Solar thermal cannot do this - it can only heat the xxx L store you have and that's its


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