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Solar PV & thermal – Domestic intergation.

  • 11-04-2023 6:14pm
    Registered Users Posts: 586 ✭✭✭

    I have a solar thermal set up in place for the last 10 years plus. It has been reasonably trouble free and has come into its own during COVID, with a growing family at home more often. However, I am considering solar PV for my electrical demand. Allowing for correct sizing of a new system, are there examples of integrating the two systems. Do they just operate independently.

    I have no desire/need to get rid of the solar thermal, it works well, is paid for and for hot water it is the more efficient use of the sun’s ray. I have googled to see if there are ready solutions, but it seems that the information is for the sale of one or the other.

    Longer term, I would be seeking to have an air heat source pump installed once the gas boiler is due for replacement. The issue (I think) is that I will have a hot water cylinder heated as now by solar thermal, I guess with an option to have it heated via the Solar PV. In due course there would be a need to integrate the air source heat pump. Is it possible?



  • Moderators, Home & Garden Moderators Posts: 5,742 Mod ✭✭✭✭graememk

    Do you have an immersion?

    Then the excess solar pv can run that via an eddi (hot water diverter)

    They operate completely independently from each other.

    If you get A2W heatpump it can heat your water like it normally does now, through a coil in the hot water tank.

  • Registered Users Posts: 281 ✭✭JayBee66

    We also had solar thermal for 10 years afore getting PV. They are separate entities with no issues running them side by side. The thermal provides all hot water in summer and for part of spring/autumn. For the rest of the year the solar pre-warms the water and the PV does the rest through the immersion heater.

    If you have a battery with the PV and run the immersion when there are no other large loads so that the inverter/battery/sun can handle the immersion alone then you shouldn't use any grid at all throughout the year to provide hot water.

    We don't bother with a diverter, using the immersion when needed. We prefer to export as much power as we can (we have a smart meter). You can waste a lot of export by dumping it into the hot water cylinder and then let the heat (energy) dissipate through not using it.

    Finally, we are considering a heat pump. If we get it then the solar thermal with go. The HP will come with a new tank, which would need a third coil. We will use the HP to heat water and use the space where the thermal collector was for more PV panels.