Noticed some changes? You can read all about the improvements we've made on the Forum in our latest announcement. We also have a new set of Forum rules so please take the time to give them a read and familiarise yourself.

Fronius Inverter Clunking Noise in low light

edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
5 replies 1.8K views
JimLadJimLad Forumite
918 Posts
Mortgage-free Glee! Rampant Recycler Xmas Saver!
edited 30 November -1 at 1:00AM in Green & Ethical MoneySaving
Hi Guys,

I have a Fronius IG TL inverter and when there is low light in the morning and evening it makes very loud clunking / clicking sounds which can be heard quite loudly in the bedroom below (its in the loft).

I climbed up into the loft to observe what the screen was saying and it cycles between "STATE 307 DC LOW" and "WAIT GRID TEST". Each time it cycles it makes the clunking noise.

I had a look in the manual and it says....

"Status Code 306 (Power Low) and 307 (DC Low) appear naturally every morning and evening due to low solar irradiance. These status codes are not the result of a fault"

Does anyone else have this? The noises is very annoying and has woken me up a couple of times recently. Although with the days drawing in, it wont be doing it until later in the morning soon!
Mortgage Free 22/03/17
MissWillow is my OH!


  • EctophileEctophile Forumite
    5.4K Posts
    Ninth Anniversary 1,000 Posts Name Dropper
    I've occasionally caught my inverter (not a Fronius one) doing a similar thing. However, my one ticks fairly quietly, so I don't hear it outside the loft.

    In poor light, there's just enough power to wake the inverter up. So it goes through its self-tests and then tries to connect to the mains - with a corresponding ticking as relays connect.

    But as soon as it starts trying to generate to the grid, the voltage from the solar panels dips, and the inverter shuts down.

    And the process repeats again, and again, until the daylight brightens a bit.
    If it sticks, force it.
    If it breaks, well it wasn't working right anyway.
  • Martyn1981Martyn1981 Forumite
    11.9K Posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    In the summer I hear my WNW inverter wake up, as it's in the loft not far from the bedroom. It makes a few loud clicks. The rest of the year I don't notice as it probably comes on later.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • JimLadJimLad Forumite
    918 Posts
    Mortgage-free Glee! Rampant Recycler Xmas Saver!
    Thanks guys sounds like its normal then. Normal but annoying at this time of year!
    Mortgage Free 22/03/17
    MissWillow is my OH!
  • TrickyDicky101TrickyDicky101 Forumite
    3.5K Posts
    Tenth Anniversary 1,000 Posts
    I have a Fronius and it makes exactly those sounds you describe. Mine is also in the loft and I seem to remember being mildly concerned back when first installed in 2011 but over the years I have just learned to accept it (and generation doesn't appear to be impacted). Fortunately unless I'm physically in the loft I don't hear it at all.
  • [Deleted User][Deleted User] Forumite
    0 Posts
    Part of the Furniture 1,000 Posts Photogenic
    MoneySaving Newbie
    Fronius here too and in the loft totally inaudible. I know the noise you mean but nowhere near as bad here. Ours is attached to brick gable end and is the 4.0 model. Cheers
This discussion has been closed.