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PV panels converter for water heating

  • 28-10-2021 6:06pm
    Registered Users Posts: 1,753 ✭✭✭ bittihuduga

    we have solar pv panels installed on the roof.

    one of the guys at the site said, we can get some sort of converter which can be installed to convert pv panels for water heating

    i have no idea what it is.

    has anyone come across such converters?

    it will be more savings with water heating rather than electricity generation


  • Registered Users Posts: 1,540 ✭✭✭ jkforde

    they're called a hot water diverter (HWD), for example..

    I've no affiliation with myEnergi, just a happy customer

  • Registered Users Posts: 6,515 ✭✭✭ the_amazing_raisin

    As jkforde said, the device you're looking for is a solar energy diverter

    It's pretty simple really, you just replace the controller for your immersion heater with it. It'll have a current sensor which clips onto your mains feed and tells the diverter when you're sending excess power to the grid

    When this happens, the diverter will switch on your immersion heater and try to put that exported energy to better use

  • Registered Users Posts: 1,753 ✭✭✭ bittihuduga

    thank you both. i need to do some reading on how it works.

    currently the water heating is through our gas heating system.

    solar is for power generation.

    i have to study how the solar energy diverter can be included in the setup, so that water can be heated using the excess power generated.

    also if there is no excess power, then will water be heater through normal gas heating by using timers/boost button?

  • Registered Users Posts: 1,540 ✭✭✭ jkforde

    fossil fuel water heating is unaffected, Eddi controls the immersion element(s) only.

  • Registered Users Posts: 6,515 ✭✭✭ the_amazing_raisin

    Basically it'll only switch the immersion on when there's excess solar. When your gas heating comes on and if the water is already at the setpoint (60C for example) then it just won't heat the water because it's already hot enough

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  • Registered Users Posts: 6,515 ✭✭✭ the_amazing_raisin

    On a related topic, has anyone found any good systems to integrate a heat pump with a solar PV diverter? I know the Eddi can do it for heat pumps that use old style controllers, but a lot of heat pumps now have proprietary controllers that don't seem to work well with a diverter

    Best solution seems to be to have an Eddi or similar connected to immersion heaters in the hot water and heating buffer tanks. So of there's a lot of excess solar you can heat the water for the space heating as well (good luck in winter)

    It'd be great if there was something smarter though. For example if the heat pumps saw power being exported it could switch on and modulate it's power usage to match the export, to give finer control

    Also, a lot of heat pumps are now coming with cooling functions as well. It'd be nice if they could use excess solar to chill the buffer tank so that you can cool the house down on hot days. This seems a better use case since there's a lot more excess power in summer anyway