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Domestic Battery Storage - G83/G98 - Earthing Arrangements + More

vantech
Hi,


I am looking to add a battery storage system to my own home (I am an NICEIC registered contractor, just to make it clear this is a project for myself). This will be a battery only solution, and will not feature any solar arrangements. 


If there are any experts here that can advise on a few questions, that would be superb. 

 
  • GN98 (formally GN83) allows systems up to 16A per phase to be connected without the need for any sort of site inspection before the install (so the solution is notified after). I plan on doing this myself, and I am not part of a microgeneration scheme, but assume self certification is ok, following Part P requirements and issuing the relevant certs to the NIC. 


 

  • The battery I plan on using is the Alpha ESS (combined battery and inverter), which is grid tied with separate backup output(s) for things like lighting circuits and small power circuits. I have a smart meter, however I do not have a feed-in tariff, therefore by means of a CT connected to the battery I plan to set the feed-in to zero using the inverters user interface, so that the battery just delivers power to loads as and when its required. My question here however leads me onto earthing - when running in backup mode, the inverter automatically disconnects the grid and provides power on its dedicated backup connection - what do I do with the Earthing? I am on a TN-C-S supply from the DNO - I would assume an earth rod is required, connected into the MET (as the DNO earthing cannot be relied upon during an outage) which would be combined the DNO earthing (so a rod in the ground connected to the MET and bonded onto the battery inverter). Assuming this is correct, does the inverter need to tie its backup output neutral and earth conductors together, forming its own TN system (it could even be doing this internally I'm not sure and need to check). 


 

  • Anything else I may be missing?



Thanks.

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  • 0
    vantech:
    Chris Pearson:

    What happens if the off peak rate goes up because with loads of people charging EVs, it is no longer off peak?




    You can secure tariffs for EV charging now, e.g., you have lower rates from 9pm until 7am for charging, but can use this time to charge batteries. 


    If we worked everything in life basis "what if" we wouldn't get much done - the project makes sense and is actually done by the "X" thousands who use Tesla Power Walls, many without solar. 




    I cannot help feeling that vantech is seeking validation for a project which he himself (or she herself) doubts. If not, why pose the question?


    What ifs? Well, you need to consider a range of possibilities in any business plan. Not just Tesla power walls, but IIRC, Nissan/Eaton battery set ups.


    An alternative mechanism is to leave an EV plugged in 24/7. Charge at cheap rates, but use during the day if not travelling.


    I cannot help feeling that sound energy management is a better solution. If you have enough usage to make it viable to have variable rates, heat water at night, wash clothes and crockery at night, etc. It might even make sense to wash (oneself) before bed (at say, 23:00) rather than on rising (at say, 07:00).


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  • 0
    vantech:
    Chris Pearson:

    What happens if the off peak rate goes up because with loads of people charging EVs, it is no longer off peak?




    You can secure tariffs for EV charging now, e.g., you have lower rates from 9pm until 7am for charging, but can use this time to charge batteries. 


    If we worked everything in life basis "what if" we wouldn't get much done - the project makes sense and is actually done by the "X" thousands who use Tesla Power Walls, many without solar. 




    I cannot help feeling that vantech is seeking validation for a project which he himself (or she herself) doubts. If not, why pose the question?


    What ifs? Well, you need to consider a range of possibilities in any business plan. Not just Tesla power walls, but IIRC, Nissan/Eaton battery set ups.


    An alternative mechanism is to leave an EV plugged in 24/7. Charge at cheap rates, but use during the day if not travelling.


    I cannot help feeling that sound energy management is a better solution. If you have enough usage to make it viable to have variable rates, heat water at night, wash clothes and crockery at night, etc. It might even make sense to wash (oneself) before bed (at say, 23:00) rather than on rising (at say, 07:00).


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