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Backup power to consumer unit in power cut

  • 04-07-2021 11:36am
    #1
    Registered Users Posts: 2,793 ✭✭✭ irishchris


    Ended up with yet another power cut here yesterday for several hours due to thunder and lightening. Am in process of moving my inverter, battery etc to a shed from my house and setting up the eps on it which I hadn't wired prior to now as knew it would be moved shortly after original install.
    My plan was to have power brought in from the backup on Solis inverter on swa cable into an indoor socket originally. However now thinking would be loads better off if could be brought to main consumer unit via a changeover switch. Have many here done that? If so how do you find it works?


Comments

  • Registered Users Posts: 2,752 ✭✭✭ graememk


    Haven't done it but have been told that that your not meant to feed the hybrid inverter it's own eps supply.

    Eg it comes from the eps, to the fuse board and then back out to the Inverter.


  • Registered Users Posts: 2,793 ✭✭✭ irishchris


    graememk wrote: »
    Haven't done it but have been told that that your not meant to feed the hybrid inverter it's own eps supply.

    Eg it comes from the eps, to the fuse board and then back out to the Inverter.

    Interesting hadn't heard that. I wonder could you turn off the Ac switch supply to inverter before clicking the changeover switch


  • Registered Users Posts: 2,752 ✭✭✭ graememk


    irishchris wrote: »
    Interesting hadn't heard that. I wonder could you turn off the Ac switch supply to inverter before clicking the changeover switch

    Yep that would be fine. Its only second hand information that was said in an off hand comment, but sorta makes sense. it would be trying to balance against its own supply.


  • Registered Users Posts: 5,876 ✭✭✭ the_amazing_raisin


    I'm not familiar with Solis systems but in general I think you can install a device called an anti islanding circuit to have backup power in the even of a power cut

    It's essentially a relay on the mains connection which will open the circuit if the grid power is lost and won't allow a reconnect until the power is restored

    This should allow you to wire your inverter into your house supply in whatever way the manufacturer recommended and then in a grid power cut you'll still have power from your PV system

    In general the logic for the ESB is that they can't have any active generators on the grid during an outage, so that the ESB engineer working on the repair doesn't accidentally get electrocuted while trying to fix a supposedly dead circuit


  • Registered Users Posts: 2,793 ✭✭✭ irishchris


    I'm not familiar with Solis systems but in general I think you can install a device called an anti islanding circuit to have backup power in the even of a power cut

    It's essentially a relay on the mains connection which will open the circuit if the grid power is lost and won't allow a reconnect until the power is restored

    This should allow you to wire your inverter into your house supply in whatever way the manufacturer recommended and then in a grid power cut you'll still have power from your PV system

    In general the logic for the ESB is that they can't have any active generators on the grid during an outage, so that the ESB engineer working on the repair doesn't accidentally get electrocuted while trying to fix a supposedly dead circuit

    As far as I'm aware the Solis has anti islanding built in so as soon as grid is disconnected it automatically stops feeding power out through its main grid output. It's backup AC (EPS) will kick in then. I am looking to have this if possible fed into main consumer unit by means of a changeover switch. By this means it should stop power out to grid in event of a grid failure but supply power to my house. Just wondering if anybody here has done similar?


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  • Registered Users Posts: 5,876 ✭✭✭ the_amazing_raisin


    irishchris wrote: »
    As far as I'm aware the Solis has anti islanding built in so as soon as grid is disconnected it automatically stops feeding power out through its main grid output. It's backup AC (EPS) will kick in then. I am looking to have this if possible fed into main consumer unit by means of a changeover switch. By this means it should stop power out to grid in event of a grid failure but supply power to my house. Just wondering if anybody here has done similar?

    Ah okay, I just took a quick look at the manual and my understanding is that if you connect the grid input of the Solis to the output of the meter box and then the Backup output feeds your CU then that'll basically do what you want

    Would mean running more wires of course so it may not suit your setup. But it does seem like the simplest solution

    It would also mean that all of your loads are critical loads so you'll probably need to do some power management manually


  • Registered Users Posts: 2,793 ✭✭✭ irishchris


    Ah okay, I just took a quick look at the manual and my understanding is that if you connect the grid input of the Solis to the output of the meter box and then the Backup output feeds your CU then that'll basically do what you want

    Would mean running more wires of course so it may not suit your setup. But it does seem like the simplest solution

    It would also mean that all of your loads are critical loads so you'll probably need to do some power management manually

    Yep I think would have to be careful in terms of what I could run but if power cut during the day like yesterday at least the solar would run the house and keep the battery full. Not sure of the full power available in EPS mode so must check that out also but would at least run the two freezers and fridges without having to be running extension leads etc plus should be able to keep PC or TV etc running


  • Registered Users Posts: 11,226 ✭✭✭✭ KCross


    irishchris wrote: »
    Yep I think would have to be careful in terms of what I could run but if power cut during the day like yesterday at least the solar would run the house and keep the battery full. Not sure of the full power available in EPS mode so must check that out also but would at least run the two freezers and fridges without having to be running extension leads etc plus should be able to keep PC or TV etc running

    Personally I think it’s a bad idea. You are asking for trouble with your electronic devices as the power will be varying too much. Unless you stuck a UPS in between.

    As an aside I do have a changeover switch myself which could be used like you’ve said but I use it for a petrol generator. It is brilliant when the need arises. No extension leads etc. Just fire it up and ensure you don’t start ovens etc. Keep it to lights, internet, tv, water.


  • Registered Users Posts: 2,793 ✭✭✭ irishchris


    KCross wrote: »
    Personally I think it’s a bad idea. You are asking for trouble with your electronic devices as the power will be varying too much. Unless you stuck a UPS in between.

    As an aside I do have a changeover switch myself which could be used like you’ve said but I use it for a petrol generator. It is brilliant when the need arises. No extension leads etc. Just fire it up and ensure you don’t start ovens etc. Keep it to lights, internet, tv, water.

    Would it not be the same with a generator in terms of fluctuation? I'm planning on only running the fridges and freezers (200-300w), router and maybe TV/pc (300-400w) so max 700/800w. The battery should supply a steady current and stay topped up during the day via the solar PV. Or am I missing something here (and there's a good chance I am :-) )


  • Registered Users Posts: 5,876 ✭✭✭ the_amazing_raisin


    irishchris wrote: »
    Would it not be the same with a generator in terms of fluctuation? I'm planning on only running the fridges and freezers (200-300w), router and maybe TV/pc (300-400w) so max 700/800w. The battery should supply a steady current and stay topped up during the day via the solar PV. Or am I missing something here (and there's a good chance I am :-) )

    I suppose the worry is that you're using something like the oven when the power cuts and it'll pull more power than the inverter and battery can supply at that time, could cause the voltage to droop which would be bad for sensitive equipment


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  • Registered Users Posts: 2,793 ✭✭✭ irishchris


    I suppose the worry is that you're using something like the oven when the power cuts and it'll pull more power than the inverter and battery can supply at that time, could cause the voltage to droop which would be bad for sensitive equipment

    Ah I see. No I would ensure I turned off the power hungry devices prior to turning off AC switch and moving the changeover switch. I thought maybe was something else I was missing, many thanks


  • Registered Users Posts: 11,226 ✭✭✭✭ KCross


    irishchris wrote: »
    Would it not be the same with a generator in terms of fluctuation? I'm planning on only running the fridges and freezers (200-300w), router and maybe TV/pc (300-400w) so max 700/800w. The battery should supply a steady current and stay topped up during the day via the solar PV. Or am I missing something here (and there's a good chance I am :-) )

    Yes and no. If your lucky and the power cut happens after the battery is full and/or the sun is giving good generation then yes... all good.

    The alternative isn’t so clear though... say power goes out at 10am unexpectedly and you switch over your supply you could easily drain the battery or pull too much current.

    It would need to be carefully managed and monitored throughout the power cut. If the battery is drained and your working off live generation and a cloud rolls over it will cause another power cut or if you are just about generating enough and then the fridge comes on it tips it over the edge... these type of events are not good for electronics.

    A petrol generator is simpler. It generates a constant known kW as long as you keep petrol in it!


  • Registered Users Posts: 791 ✭✭✭ reklamos


    On solis there is an option to configure battery reserve so you would always have some juice to run the essentials. Making sure that it is only essentials that are connected would be crucial as the max that solis can provide is 3kW on backup output. So no tea kettles.



  • Registered Users Posts: 2,793 ✭✭✭ irishchris


    With kettle only running at 2kw would this not be possible then? I thought with 3kw it was?



  • Registered Users Posts: 791 ✭✭✭ reklamos


    That is if your kettle is really 2kW as many of them are actually 3kW and you need to take into account other house load at that time. You have not mentioned your battery size but it is another factor to be aware of. If you have a single small battery like pylontech 2000 then the your max discharge rate is 2.5kW.



  • Registered Users Posts: 2,793 ✭✭✭ irishchris


    I have verified the load of my kettle is max 2kw and together with house load and kettle only it seems to be about 2.4kw.

    I have one us2000 and max discharge is only 1.2kw not 2.5kw.

    I plan to add a us3000 to it as soon as stock is back and that has a discharge of 1.8kw so should give me 3kw backup discharge power.

    The attached screenshot is now with kettle boiling, my sons Xbox and screen on, main TV on and house load. Would not expect anymore than this to be on with backup power.



  • Registered Users Posts: 5,876 ✭✭✭ the_amazing_raisin


    If the power is out then the internet signal might be down as well, so powering the router might be unnecessary



  • Registered Users Posts: 2,793 ✭✭✭ irishchris


    I pick my broadband up from three mast in the opposite direction to the local power station so thankfully when power goes I generally have phone signal too



  • Registered Users Posts: 2,752 ✭✭✭ graememk


    And the Mobile phone masts are bound to have backup generators.. well because they'll be needed if something ever does happen!



  • Registered Users Posts: 791 ✭✭✭ reklamos


    Max charge/discharge of us2000 is 50A with peak 100A so it can do 2.4kW. Probably it is limited by your inverter settings.



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  • Registered Users Posts: 2,793 ✭✭✭ irishchris


    Interesting must be my Solis then. Anyone else here with us2000 pylon batteries and a solis, what is the discharge rate on yours?



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