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Heat Pump and Solar PV

  • 01-09-2020 11:56pm
    #1
    Registered Users Posts: 1,146 ✭✭✭ Nelbert


    Hi,

    We're heading towards renovating the house and based on recommendations we're getting a heat pump, new attic insulation and internal insulation.
    We consume 5-6k units of electricity a year and obviously this will go up with the install of the heat pump (hopefully by less than the reduction in gas....).

    Over the last few days I've begun to research solar PV though as logically it would seem a good pairing, and potentially offset the heat pump electricity cost.

    Rear of house faces approx 135 degrees (south east).

    Would a small solar PV system be worth considering (I see they can by close to 3k cost after grants)?
    The panels could go on roof of new extension but I'd be concerned of summer shadows from the house restricting output. But we've a shed that could house panels (assuming there's no issue with running them back to house).

    Any help navigating this maze of info would be appreciated.


Comments

  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,884 CMod ✭✭✭✭ unkel


    A solar PV system is always worth considering. Presuming your house was built before 2011 you will get a substantial subsidy too if you go with one of the SEAI installers. Or you could do a DIY install

    Shadowing is bad, but you can attach an optimizer to every panel that gets shadow. A few panels on the shed is fine too, as long as the run of the cable is not huge (like 20-30m is still fine)

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 4,170 ✭✭✭ BoardsMember


    Interested to hear the replies.

    I've been doing some research, and I just can't make the case for similar aporoach: PV and heat pump.

    Solar PV to help with the cost of the heat pump....need heat in mornings and evenings/nights when the PV isn't generating anything of significance.

    Solar PV to help reduce electricity....batteries too expensive to make storing electricity viable, not generating electricity when most needed (evenings), most systems giving away excess electricity as its generated when not needed, albeit people with EVs make better use of it.

    The heat pump works best in summer when you don't need it. Also works best for lower temp water, so won't do showers, except a costly heat pump, really needs oversized radiators and/or underfloor heating.

    The above is probably under or mis informed, so apologies if I put peoples' noses out. I'd like to be persuaded, or shown the light, if you'll excuse the pun.


  • Registered Users Posts: 1,146 ✭✭✭ Nelbert


    We're getting UFH on ground floor and rads upstairs. Boiler needs replacing will extension and extra bedroom anyway so it's not much more for heat pump Vs combi.

    Windows getting replaced and insulation being done also helps.

    A reduction in building vat or increased grants for either the heat pump or solar in the budget in October would also be a help to overall budget.


  • Registered Users Posts: 11,213 ✭✭✭✭ KCross


    Nelbert wrote: »
    Over the last few days I've begun to research solar PV though as logically it would seem a good pairing, and potentially offset the heat pump electricity cost.

    By all means get a heat pump and Solar PV but dont get Solar PV because you have a heat pump.

    Solar PV wont offset very much of your heat pump usage.

    Solar PV is primarily to offset your daytime electricity usage. The heat pump will be running at night and primarily in the winter when SolarPV will be providing next to nothing relative to what your heat pump will be consuming.


  • Registered Users Posts: 105 ✭✭ Coltrane


    Interested to hear the replies.

    I've been doing some research, and I just can't make the case for similar aporoach: PV and heat pump.

    Solar PV to help with the cost of the heat pump....need heat in mornings and evenings/nights when the PV isn't generating anything of significance.

    Solar PV to help reduce electricity....batteries too expensive to make storing electricity viable, not generating electricity when most needed (evenings), most systems giving away excess electricity as its generated when not needed, albeit people with EVs make better use of it.

    The heat pump works best in summer when you don't need it. Also works best for lower temp water, so won't do showers, except a costly heat pump, really needs oversized radiators and/or underfloor heating.

    The above is probably under or mis informed, so apologies if I put peoples' noses out. I'd like to be persuaded, or shown the light, if you'll excuse the pun.


    Spot-on, on everything, in my experience, except that a HP will manage the hot water for your shower, at a decent co-efficient of performance, unless you like it really scalding!


    And that when making the economic/general case for investing in PV, we need to consider the economic/general consequences of not addressing climate change, within the time remaining available to us to do so!


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  • Registered Users Posts: 1,146 ✭✭✭ Nelbert


    KCross wrote: »
    By all means get a heat pump and Solar PV but dont get Solar PV because you have a heat pump.

    Solar PV wont offset very much of your heat pump usage.

    Solar PV is primarily to offset your daytime electricity usage. The heat pump will be running at night and primarily in the winter when SolarPV will be providing next to nothing relative to what your heat pump will be consuming.

    I was more so looking at it from an annual average perspective. Eliminate a 10+ year old dodgy gas boiler, electric shower, do fresh / additional attic insulation, internal wall insulation and heat pump. If the solar PV eliminated daytime elec usage for a few months a year it would be worth it.

    For reference our house will soon be occupied during the day too as children will be minded in our house rather than in mother in law's house once house work is complete.

    So I was thinking all the additional daytime house usage could shift my electricity usage profile for both the heat pump and solar PV to be worthwhile options.

    Is there any issue with 30 metre run back to meter if the solar panels were to go on shed roof?


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,884 CMod ✭✭✭✭ unkel


    Nelbert wrote: »
    Is there any issue with 30 metre run back to meter if the solar panels were to go on shed roof?

    That's no issue at all.

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



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