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Solar Voltage Rise, a spanner in the FIT works?

  • 23-03-2021 6:11pm
    #1
    Registered Users Posts: 3,911 ✭✭✭ mp3guy


    I've hit a really unusual problem that is apparently quite common in countries where domestic solar is more widespread (Australia), Solar Voltage Rise

    My house is really really close to the transformer. I'm literally the only property on the transformer and there's probably only 50m of cable from it to my meter. So my voltage is typically around 243V at idle. Problem occurs when I feed in (not even a huge amount, 2kW sometimes), I end up popping the 253V limit and my inverter has to put on the handbrakes!

    This has little to do with the size of my setup, but more to do with my local grid supply. As the article above alludes, this will become more and more of a problem as more people get solar. It's not excess power that's the problem, it's excess voltage.

    I'm currently looking at solutions to fix this on my inverters themselves, but this could throw off people whose plans involve feeding in a lot of electricity in the Summer.


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Comments

  • Registered Users Posts: 2,685 ✭✭✭ graememk


    Yep bumped into that today too,

    Although, more voltage is more power to push more electricity out onto the grid, the inverter has to raise its voltage.

    Hits voltage limit and stop, then it slowly ramps the power back up again.


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    graememk wrote: »
    Yep bumped into that today too,

    Although, more voltage is more power to push more electricity out onto the grid, the inverter has to raise its voltage.

    Hits voltage limit and stop, then it slowly ramps the power back up again.

    What inverter do you have? Curious to know your setup, distance from transformer, number of other properties on the transformer etc.. What your voltage is when the inverter is off / not supplying any power (from PV or battery).

    Fronius have a great video explaining the problem here (video linked at starting time) https://youtu.be/X8tsQhp7hM0?t=1137


  • Registered Users Posts: 2,685 ✭✭✭ graememk


    mp3guy wrote: »
    What inverter do you have? Curious to know your setup, distance from transformer, number of other properties on the transformer etc.. What your voltage is when the inverter is off / not supplying any power (from PV or battery).

    Fronius have a great video explaining the problem here (video linked at starting time) https://youtu.be/X8tsQhp7hM0?t=1137

    at least 5 properties, transformer is about 200 m away, about 5 properties, (2 with solar. although my parents wasn't exporting much)

    Currently at 237 on both mine and my parents house,
    Peaked at 251.1, Happened not long after battery finished charging.

    Solis inverters, a 6kw on mine, 5kw on parents, was generating 5.6kwish when it cut off, and most of it was being exported.

    No CT's on the inverters as they are within the limit.


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    I took a peak at the Solis docs and it doesn't look like they have any voltage-based limiting functionality.

    Fronius and SolarEdge apparently do and as far as I can tell SolaX also does, but it's not very clear how to configure it properly from any manuals.

    Given the prevalence of Solis inverters in Ireland I reckon this is a ticking time bomb.


  • Registered Users Posts: 2,685 ✭✭✭ graememk


    mp3guy wrote: »
    I took a peak at the Solis docs and it doesn't look like they have any voltage-based limiting functionality.

    Fronius and SolarEdge apparently do and as far as I can tell SolaX also does, but it's not very clear how to configure it properly from any manuals.

    Given the prevalence of Solis inverters in Ireland I reckon this is a ticking time bomb.

    Does yours just currently cut out when it hits the limit?


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  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    graememk wrote: »
    Does yours just currently cut out when it hits the limit?

    Yeah, once the voltage hits the programmed limit (253V) it just dies. See output power:

    yokJ3f2.jpg

    And voltage:

    Ea5WOW8.jpg

    There are references to reactive power control modes and volt-watt response modes in the manual so I'm working with my installer and SolaX to figure out what's the right setting. This is only really a problem for export, won't affect self consumption.


  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    mp3guy wrote: »
    I took a peak at the Solis docs and it doesn't look like they have any voltage-based limiting functionality.

    Fronius and SolarEdge apparently do and as far as I can tell SolaX also does, but it's not very clear how to configure it properly from any manuals.

    Given the prevalence of Solis inverters in Ireland I reckon this is a ticking time bomb.

    [edit] Sorry - after posting I realised by voltage limiting functionality, you meant power limiting. That is not present on many brands, but you still lose production with it. It is better to see if you caan get permission to adjust the 253v limit up to 255 or 260. In UK, the limit is 264 because their nominal is 240. Ours is meant to be 230]

    You can adjust the voltage range on most inverters, including Solis, but you are then in breach of EN5048 (soon to be EN51545). ESB sometimes gives permission to do this but I have never seen them do so in writing.

    Your grid connection to the inverter should be on a cable heavy enough to ensure voltage drop <= 1%. I would try reading grid voltage at the consumer unit with a multimeter to check this isn't exacerbating the problem.

    This is often a problem on sites close to wind farms. When they roll out solar parks, it will get worse because their output will peak at the same times.


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    [edit] Sorry - after posting I realised by voltage limiting functionality, you meant power limiting. That is not present on many brands, but you still lose production with it. It is better to see if you caan get permission to adjust the 253v limit up to 255 or 260. In UK, the limit is 264 because their nominal is 240. Ours is meant to be 230]

    You can adjust the voltage range on most inverters, including Solis, but you are then in breach of EN5048 (soon to be EN51545). ESB sometimes gives permission to do this but I have never seen them do so in writing.

    Your grid connection to the inverter should be on a cable heavy enough to ensure voltage drop <= 1%. I would try reading grid voltage at the consumer unit with a multimeter to check this isn't exacerbating the problem.

    This is often a problem on sites close to wind farms. When they roll out solar parks, it will get worse because their output will peak at the same times.

    Well there are two methods for limiting voltage as outlined by the Aus/NZ standard in the Fronius video, one is based on limiting exported power back to the grid when approaching the voltage limit. The other is about manipulating the power factor to leverage reactive power to control the voltage (not sure how much this affects the resultant exported power). Again, all this only impacts the power you feed back in, so only a problem if FIT is a big part of your plan. Otherwise, your inverter will keep cycling and you will lose self consumption power as well as exported.

    That's interesting to hear anecdotally the ESB might permit a higher voltage limit, I might see what I can do there. I'm not near any other (micro) generators, in a typical rural environment, just single phase.

    We've got 16mm2 through and through with the inverters so I think I'm alright cable size wise. I do have a voltage measurement at the consumer unit and down at the inverters and they concur.


  • Registered Users Posts: 5,112 ✭✭✭ Ubbquittious


    I must really install more solar panels. Rare enough to see over 230 these parts and below 220 is common. Some days my compressor wont even start the voltage is too low. Only 3 houses on the transformer I think

    Stellantis: All the sh1t brands under one roof



  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    ESB are coming out to install a voltage monitor for 10 days and then see what can be done / they're willing to do. Hoping they're flexible given there are no other houses on my transformer and likely never will be.


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  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    If someone has this issue happening on a Solis inverter, PM me. I may have a setting that can remedy it, but I would need someone on a site with this issue to test it.


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    If someone has this issue happening on a Solis inverter, PM me. I may have a setting that can remedy it, but I would need someone on a site with this issue to test it.

    What's the setting, out of curiosity?


  • Registered Users Posts: 11,177 ✭✭✭✭ KCross


    mp3guy wrote: »
    ESB are coming out to install a voltage monitor for 10 days and then see what can be done / they're willing to do. Hoping they're flexible given there are no other houses on my transformer and likely never will be.

    They can, i think, change the windings in the transformer to lower your voltage which would be the opposite of the usual complaint!

    Or they might just swap out your transformer.

    Another likely prospect is that they say the voltage is within the spec of the regulator and hence do nothing.... thats what the voltage monitor will tell them. I've had that done on my house for low voltage. They have to do that to gather the stats in case you create an issue with the regulator. There are specific guidelines around what the voltage can/cannot be over a preiod of time.


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    KCross wrote: »
    They can, i think, change the windings in the transformer to lower your voltage which would be the opposite of the usual complaint!

    Or they might just swap out your transformer.

    Another likely prospect is that they say the voltage is within the spec of the regulator and hence do nothing.... thats what the voltage monitor will tell them. I've had that done on my house for low voltage. They have to do that to gather the stats in case you create an issue with the regulator. There are specific guidelines around what the voltage can/cannot be over a preiod of time.

    I wonder if they'll ask me to turn off my solar inverters for the 10 days. I'm inclined not to (which means they'll record the voltage breaching 253V).

    It'd be the same if say I had low voltage around 210V and turned on our electric shower (which drops the grid reading by 9-10V last time I checked). They'd record < 207V, and would have to fix it.


  • Registered Users Posts: 11,177 ✭✭✭✭ KCross


    mp3guy wrote: »
    I wonder if they'll ask me to turn off my solar inverters for the 10 days. I'm inclined not to (which means they'll record the voltage breaching 253V).

    It'd be the same if say I had low voltage around 210V and turned on our electric shower (which drops the grid reading by 9-10V last time I checked). They'd record < 207V, and would have to fix it.

    Thats the kicker, they dont have to just because you get a few high or low readings.

    They are allowed some leeway over a period of time. Its all clearly laid out as to what the criteria for a pass or fail is. If it fails they have to fix it but a few high or low readings over those 10 days wont be enough for a fail.


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    KCross wrote: »
    Thats the kicker, they dont have to just because you get a few high or low readings.

    They are allowed some leeway over a period of time. Its all clearly laid out as to what the criteria for a pass or fail is. If it fails they have to fix it but a few high or low readings over those 10 days wont be enough for a fail.

    Yeah that's what I'm worried about. Just gotta wait and see.


  • Registered Users Posts: 11,177 ✭✭✭✭ KCross


    mp3guy wrote: »
    Yeah that's what I'm worried about. Just gotta wait and see.

    Here's the result I got and the regulations, so you have an idea of what they are allowed "get away with"!

    https://www.boards.ie/vbulletin/showpost.php?p=106706752&postcount=57


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    KCross wrote: »
    Here's the result I got and the regulations, so you have an idea of what they are allowed "get away with"!

    https://www.boards.ie/vbulletin/showpost.php?p=106706752&postcount=57

    Oh nice, thanks for linking that. How did you resolve things in the end?


  • Registered Users Posts: 11,177 ✭✭✭✭ KCross


    mp3guy wrote: »
    Oh nice, thanks for linking that. How did you resolve things in the end?

    The original problem with the HP tripping was resolved by increasing its trip limit!

    The HP manufacturer guided me on how to do that.

    I havent had any issues since and ESB didnt do anything eventhough my voltage went down to the low 200s during their test.


  • Registered Users Posts: 2,820 ✭✭✭ air


    ESB Networks are proposing to introduce on load tap changing transformers to mitigate the likes of this issue.
    I heard it said with regard to increasing the capacity of the local distribution network to facilitate heat pumps and EVs but of course they would also work in reverse for PV.

    In the OPs case with a dedicated transformer a manual tap change would seem sensible if the transformer in question allows for it, I'm not sure the smaller ones are adjustable though.

    They could pick a set point at the ideal point in the allowed range to balance your MIC and allowed export capacity.


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  • Registered Users Posts: 5,112 ✭✭✭ Ubbquittious


    air wrote: »
    ESB Networks are proposing to introduce on load tap changing transformers to mitigate the likes of this issue.
    I heard it said with regard to increasing the capacity of the local distribution network to facilitate heat pumps and EVs but of course they would also work in reverse for PV.

    In the OPs case with a dedicated transformer a manual tap change would seem sensible if the transformer in question allows for it, I'm not sure the smaller ones are adjustable though.

    They could pick a set point at the ideal point in the allowed range to balance your MIC and allowed export capacity.


    Interesting. I'd say you could be waiting a long time for one of those transformers if you're in the shticks

    Stellantis: All the sh1t brands under one roof



  • Registered Users Posts: 5,112 ✭✭✭ Ubbquittious


    Stellantis: All the sh1t brands under one roof



  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    mp3guy wrote: »
    What's the setting, out of curiosity?
    I tried this setting since on an inverter here and the option isn't available for the Irish grid standard. Solis says they may correct this on future versions of the firmware.


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    Just found out about voltage optimisers: https://energyace.co.uk/voltage-optimisation-residential/

    Anyone heard about these before?


  • Registered Users Posts: 2,820 ✭✭✭ air


    Yes, run, a mile!


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    air wrote: »
    Yes, run, a mile!

    Would be great if you could expand on this. Used one before?


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    Looks like another brand is available: https://www.nuvisionenergy.co.uk/opti-volt-100

    Not really paying any attention to the "SAVES YOU MONEY" aspect, more the fact it allows tapping down of the grid voltage entering the property and works with PV.


  • Registered Users Posts: 2,820 ✭✭✭ air


    They're a scam basically, different outfits have been pushing them for years.
    The whole premise they're based on is false and there is next to nothing in the magic boxes generally.


  • Registered Users Posts: 3,911 ✭✭✭ mp3guy


    air wrote: »
    They're a scam basically, different outfits have been pushing them for years.
    The whole premise they're based on is false and there is next to nothing in the magic boxes generally.

    Sorry, are you saying they categorically do not decrease the voltage? So if I buy one and measure the voltage on the input and output, it will be the same?


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  • Registered Users Posts: 2,820 ✭✭✭ air


    For many of them that will be the case, but even if they do they're not going to save you money or solve your issues with voltage rise.

    For a given export power and grid voltage you're going to see a fixed rise in voltage at your metering point.

    Whatever you put between your metering point and your PV inverters and / or loads can't change this fact.

    You risk causing even more issues in fact if you got one that did reduce voltage as your inverter would be fooled into thinking the grid voltage at your metering point was lower than it thinks
    It could keep exporting to a level that causes the voltage at your metering point to exceed the maximum voltage limit set out by EN50438.

    So as I see it you risk violating the grid interface standards by installing one of these on a connection with micro generation.

    All told, they are a waste of time and money and are in general sold by unscrupulous operators in my experience.
    That's all I have to say on them.


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