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

vantech:

broadgage:

What is the purpose of this installation ?

If simply to provide back up power during power failures, then simply use an "of the shelf" UPS unit with an extended run time battery bank. No question of parrelal operation with the DNO supply or of returning energy to the public network. GN 98 or related documents not relevant.


If the intention is sell power back into the DNO, I would give up on that idea.

Calculate the cost of charging the battery from the off peak DNO supply, and then therevenue from selling the power back at peak times, compare with cost of battery cycling.Not worth it.

Hi,


The idea would be to charge the battery on special night time rates (and lowered tariffs for EV charging) and then discharging during the day. The battery is grid tied, so during the day and up until the economy tariff begins, it will discharge with zero feed to the grid. 


So you are saying that if I am not selling back to the grid, I don't need to complete the GN98? The battery will be grid tied for the purpose of supplying loads (so it connects into an MCB to charge the battery and also to discharge when supplying loads - the backup is a separate output limited to 16A), so does the DNO not need to know there is a generation plant, even if it isn't selling back to the grid?


Thanks. 

If the equipment is to run in paralel with the grid, then approval is required.

If however your equipment is to be used INSTEAD of the grid with a changeover arrangement that prohibits interconnection, then no approval is required.


I doubt that it will be economic due to battery costs.

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. 

broadgage:

vantech:

broadgage:

What is the purpose of this installation ?

If simply to provide back up power during power failures, then simply use an "of the shelf" UPS unit with an extended run time battery bank. No question of parrelal operation with the DNO supply or of returning energy to the public network. GN 98 or related documents not relevant.


If the intention is sell power back into the DNO, I would give up on that idea.

Calculate the cost of charging the battery from the off peak DNO supply, and then therevenue from selling the power back at peak times, compare with cost of battery cycling.Not worth it.

Hi,


The idea would be to charge the battery on special night time rates (and lowered tariffs for EV charging) and then discharging during the day. The battery is grid tied, so during the day and up until the economy tariff begins, it will discharge with zero feed to the grid. 


So you are saying that if I am not selling back to the grid, I don't need to complete the GN98? The battery will be grid tied for the purpose of supplying loads (so it connects into an MCB to charge the battery and also to discharge when supplying loads - the backup is a separate output limited to 16A), so does the DNO not need to know there is a generation plant, even if it isn't selling back to the grid?


Thanks. 

If the equipment is to run in paralel with the grid, then approval is required.

If however your equipment is to be used INSTEAD of the grid with a changeover arrangement that prohibits interconnection, then no approval is required.


I doubt that it will be economic due to battery costs.

Hi,


The product is a combined inverter, battery and additional add-on batteries, which all come with a 10 year warranty, so this isn't a concern. The solution will pay for itself over a 10 year period - this is more of a nice to have rather than something to save money on - the lower economy rates are of course essential in ensuring the system pays for itself. 


The inverter is tied to and can charge from the grid, so it delivers 16amps of power to the property when demand is high, but does not sell to the grid. It has a second "backup" output, which stays on in the event of power failure, so this would be limited to a few lighting circuits - this is what I need help with, as in this mode its a generator so would require a joined N+E link. Many of the Victron inverters do this automatically, but the one I am planning to use doesn't give indication of this feature. 


You have answered my question though, I need to submit the G98 - can I self notify this? 


Thanks. 

 

The product is a combined inverter, battery and additional add-on batteries, which all come with a 10 year warranty, so this isn't a concern. The solution will pay for itself over a 10 year period - this is more of a nice to have rather than something to save money on - the lower economy rates are of course essential in ensuring the system pays for itself. 

 

RichardCS2:

vantech:

The product is a combined inverter, battery and additional add-on batteries, which all come with a 10 year warranty, so this isn't a concern. The solution will pay for itself over a 10 year period - this is more of a nice to have rather than something to save money on - the lower economy rates are of course essential in ensuring the system pays for itself. 

 

Fair enough. Is there no cycle or throughput limit in the warranty on the unit you are considering? The Tesla Powerwall for example it limited to 37.8 MWh total which you would reach in just under 7 years. https://www.tesla.com/sites/default/files/pdfs/powerwall/powerwall_2_ac_warranty_europe_1-5_english.pdf


Your numbers look better than I had expected anyway.

 

Yeah I have taken that into consideration, this is based on full use every day, and this simply won’t be the case with work, travelling etc - days when washers/dryers aren’t used, summer months etc. 


The Tesla product is 37.8MWh over 10 years, this is 3780kWh a year, with our use sitting at around 5500kWh per annum - so we are just over (assuming we use the battery for all of our requirements). Another factor actually is that the inverter is limited to 16A, so for peak power demand like induction hobs, ovens and whatever else is running at the same time, the load is split between the battery and the grid, so this will reduce the overall battery use over its lifecycle - it could break even (give or take). 

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).

Chris Pearson:

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).

Hi,


The OP was a question relating to the regulations surrounding earthing and the notification of the works to the relevant authority - I have answered all other questions with due diligence as part of the forum, not to get “approval” as you are putting it. 


If you read above, you will see reasoning for the works, and this hasn’t changed - what I am missing however is the technical input I came here for. 


Thanks. 

mapj1:

Ignoring the G code diversion, yes you can, and should add an electrode to the TNC-s system - it will appear rather like another plumbing bond to the mains most of the time, but act as main electrode when/if external supply is cut.


you are also relying on the N-E link in your cut-out  when the external supply goes off, but unlike the external cable I think it is reasonable to assume you will know if something happens to that.

M.

Thanks for this.


I agree on the rod, however if the battery is connected through an MCB, and subsequently through a main switch, you’d be relying on the main switch of the DB being “on” in order to ensure the link between PE and N, which is why the Victron units have the relay built in, so the bond happens at point of generation when grid power fails, and disconnects when it’s back up again. 


You mentioned the G code diversion, and ignoring it. What do you mean by this? 


Thanks.