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Compatibility of Solis inverters with ESB Networks

  • 14-10-2022 9:23am
    #1
    Registered Users Posts: 714 ✭✭✭


    A while ago we were in the process of installing a Solis inverter. As part of the install, you need to change the parameters on the inverter to be compatible with ESB Networks. ESB Networks have outlined these parameters in their "NC6-01-R7" form. A screenshot is shown below:

    We were able to set these parameters by going to Advanced Settings (default pin is 0010) -> Select Standard -> EN50549 and then entering them in. However, there was no option for "ROCOF".

    After a Google search, the following declaration was found from Solis:

    It appears that Solis inverters do not use RoCoF. More interestingly (highlighted in red), they use a method that used "injected perturbations" in the "AC output current".

    This appears to be in conflict with what ESB Networks specify in their NC6- 01-R7 form:

    If this is the case, how are Solis Inverters compatible with ESB Networks? Would anyone more knowledgeable have any input on this?



Comments

  • Registered Users Posts: 88 ✭✭TerraSolis


    So my understanding is that the Solis declaration is referring to harmonics which are emitted by most (all?) inverters. Harmonics are small imperfections in the AC sine wave where another signal at a harmonic frequency is also injected to the grid, but these harmonics are usually tiny compared to the actual standard 50ish Hz power injection. Read up on total harmonic distortion in power electronics if you're interested.

    In contrast, the ESBN doc is referring to the methodology by which the inverter detects that the mains is offline. Essentially it's stating that the inverter cannot inject pulses of elec to the grid to check if it is down or not, it must use some other method of detection.



  • Registered Users Posts: 714 ✭✭✭SchrodingersCat


    the ESBN doc is referring to the methodology by which the inverter detects that the mains is offline. Essentially it's stating that the inverter cannot inject pulses of elec to the grid to check if it is down or not, it must use some other method of detection.

    Yes, I agree.

    the Solis declaration is referring to harmonics which are emitted by most (all?) inverters.

    No, I don't believe that is what the document is referring to. The Solis declaration is referring to the fact that all their inverters detect the loss of mains, and the method that they employ to detect that loss of mains:

    "Ginlong Solis...declares that: All Solis inverters are capable of detecting the loss of main situations and stop generating within the time threshold required by G99 and G98 regulations. Instead of using passive detection methods like Vector Shift or RoCoF, Solis inverters utilize active frequency shift method (Sandia Frequency Shift)".

    They are stating that they do not detect the loss of mains passively: instead, they actively "injected perturbations" in the "AC output current" which looks to be in conflict with the ESBN guidelines?



  • Moderators, Home & Garden Moderators Posts: 5,510 Mod ✭✭✭✭graememk


    Solis is one of the most popular inverters in Ireland. If there was an issue with them, they wouldnt be approved here.



  • Registered Users Posts: 714 ✭✭✭SchrodingersCat


    Ive thought about this. Either:

    a) This requirement was only introduced on the NC6-01-R7 in the last year, so they aren't really enforcing it yet, or

    b) The above interpretation of the documents is wrong, but I havent seen an explanation why?

    I assume most installers are ticking "Yes" under "ROCOF Settings have been applied" without checking on their inverter whether they have been or not for the ESB approval.

    Post edited by SchrodingersCat on


  • Moderators, Education Moderators, Home & Garden Moderators Posts: 8,036 Mod ✭✭✭✭Jonathan


    A more recent Ginlong Solis declaration of EN50549 conformity for Ireland is attached below.

    Ireland isn't mentioned by name in the declaration, but the declaration references the ESBN Conditions Governing the Connection and Operation of Micro-Generation document by name, and the test parameters are the Irish specific protections for EN50549, as listed in section 2.2 of the ESBN document.

    If ESBN had a problem, I'm sure they'd be contacting SEAI to block them from the grant, and they'd be contacting those with Solis inverters listed on their NC6/NC7s.



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  • Registered Users Posts: 88 ✭✭TerraSolis


    Yes actually, sorry - I've reread that with blurry pre-coffee morning mode now disactivated and I agree with you. I actually think you're on to something here. I had also noted that this condition on the NC6 forms seems new - I don't recall it on previous versions.


    Is there a date on the Solis doc? Could it be referring to older versions of the Solis inverters?



  • Registered Users Posts: 88 ✭✭TerraSolis


    Well highlighted. I've just had a dive though - the ESBN Conditions Governing the Connection and Operation of Micro-Generation doc doesn't explicitly list the permitted forms of anti-islanding protection.


    Edit:

    Except there's an NC6 form attached at the bottom of the doc which does state this condition. Hmm.



  • Registered Users Posts: 714 ✭✭✭SchrodingersCat


    Thanks, that document is useful to have. I hadn't come across it before in my google searches. In summary, Solis are declaring that their inverters are compatible with the ESB Networks.

    How they are doing that, using a method that ESB Networks are saying that they should not use, is puzzling. 😕

    Im sure this isnt a big deal: considering that the inverters are tested by a third party to get the EN50549 certificate of conformity, they should be within the current safety parameters for the network. Secondly, if the ESBN were super worried they would be responding to the submitted NC6-01-R7 documents with "How are you claiming that your Solis inverter RoCoF settings have been applied, when a) Solis inverters dont use RoCoF and b) use an active mains disconnection detection method when they should be using a passive method?"

    Still, its a weird one. Maybe ESBN are giving folks a grace period.



  • Registered Users Posts: 714 ✭✭✭SchrodingersCat


    No worries! Thats a good point. The declaration from Solis is from 23/3/2020. Maybe its just the Solis Inverters that were being sold in 2020 that are incompatible with the new (2022) NC6-01-R7 requirements.



  • Registered Users Posts: 88 ✭✭TerraSolis


    I've been reading on this all morning. It looks like it's a new stipulation of ESBN's for sure. It effectively disallows all active anti-islanding protection methods and only allows for passive methods which are less effective at detecting islanding situations. However, it would essentially rule out most common inverters on the Irish market today as nearly all inverters have both active and passive anti-islanding protection. Solis, Fronius, Hypontech, SolarEdge, the list goes on.

    This seems regressive in terms of safety too, as passive anti-islanding is less effective with a larger 'NDZ' (non-detection zone) than active protection.

    Oddly, the same stipulation isn't listed on the NC7-01 form.

    I would expect it's going to remain under the radar for a while and non-compliance will be standard. Very well spotted.



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  • Registered Users Posts: 714 ✭✭✭SchrodingersCat


    I guess I can see where the ESBN are coming from: if there was a large amount of micro generators on the grid using an active method, rather than passive, to detect mains loss, they could interfere with each other.

    Yes, it looks like there is a large amount of Irish inverters that use an active method to detect mains loss, that is in conflict with the ESBN stipulations.

    It might be something that the ESBN will start enforcing in future.



  • Registered Users Posts: 88 ✭✭TerraSolis


    Yeah they make reference to something along those lines somewhere - I can follow the logic there for sure, but I would've thought that the lesser effectiveness of passive means of islanding detection would pose a greater safety risk to ESB linesmen (linespeople?). Particularly given that active methods like Sandia typically include some means of identifying disturbances from other inverters.

    They may start trying to enforce it, but to be honest I don't think they'll want to dedicate too many resources to it. Not every inverter specifies their anti-islanding protection mechanisms and they aren't currently asking for any form of proof or certification of anti-islanding methodology. This will be interesting to follow though. Most grids won't let you connect if you don't have active detection (e.g. Australia).



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