Multiple Batteries and DNO

[Pocster]

Having issues and conflicting info here.

 

Firstly my original installer of PV and Tesla battery seems to have disappeared. How do I contact the DNO directly to find out what I can/cannot do?

 

Secondly - conflicting info on multiple batteries! ; do they charge simultaneously? (thinking about it they must ) - but info seems to vary on this fact.

 

Anyone got multiple batteries any brand?

[Pocster]

Spoke to a few companies randomly and get confusion!

 

Most seem concerned that the DNO would not want me exporting more than 4kw ( this is my limit ).

This is fine for me.

 

So I guess I need to ask....

 

If I have 2 batteries, fully charged. Sun shining away. I'm using almost zero electric. Surely some method existing to limit my export to no more than 4kw?. I.e. I'm deliberately throttled to avoid overloading the grid. Where does 'unused' electric go??? ?

[Onoff]

42 minutes ago, pocster said:

Firstly my original installer of PV and Tesla battery seems to have disappeared.

 

Sucker! ?

[Pocster]

2 minutes ago, Onoff said:

 

Sucker! ?

It was called “ Onoff’s solar suck generation Ltd “ - I should of twigged 

[Onoff]

I've got some PV batteries to collect at some time, controller etc.

 

My sucker mate was conned into "upgrading" what he already had. 

 

 

[SteamyTea]

37 minutes ago, pocster said:

Where does 'unused' electric go

Do you mean unused from the batteries? It don't go anywhere  it just stays as chemicals.

54 minutes ago, pocster said:

Firstly my original installer of PV and Tesla battery seems to have disappeared

Was it fitted through the MCS, they may be able to help, sucker.

[Pocster]

This him???

 

 

[Pocster]

Just now, SteamyTea said:

Do you mean unused from the batteries? It don't go anywhere  it just stays as chemicals.

Was it fitted through the MCS, they may be able to help, sucker.

Suck on my PV. If PV is generating juice and batteries are full and I'm not using said juice; where does it go?

[Pocster]

This website is rubbish

[SteamyTea]

6 minutes ago, pocster said:

Suck on my PV. If PV is generating juice and batteries are full and I'm not using said juice; where does it go?

To the grid.

Is it MCS or some dodgy slave trader with fake work papers.

[Pocster]

14 minutes ago, SteamyTea said:

To the grid.

Is it MCS or some dodgy slave trader with fake work papers.

Mcs I believe 

[SteamyTea]

Just now, pocster said:

Mcs I believe 

May be worth getting in touch with them, they used to be quite helpful, unless you wanted money off them.

Your DNO should also have records of what is installed, and how. They should also know where the kill switch is, and may tell you to use it.

[Christiano]

Our DNO is UK Power Networks, they have useful info on their website (even giving outline costs for certain upgrades like moving power supply, going to 3-phases etc) as I’m sure others do.

My PowerVault battery has 2 inverter settings; 3.68 & 5.5kW. I wanted to have the higher (which is set by the PowerVault mothership) so I had to make a G99 application to the DNO. They gave me permission so long as I fitted an export limiting device (£££s) so the battery can’t export. That’s a bit useless as I got £1k off the battery if I allowed EDF to occasionally force discharge it to help balance the grid.

 

As far as I understand you can only have a single battery per phase. I think it was Robert Llewellyn from Fully Charged who had a Tesla and got a second, free Tesla due to the number of referrals he had but couldn’t put it on until he had 3-phase.

 

I think it’s because it would be a complete nightmare for 2 independent batteries to read your main power line to decide whether to charge or discharge. You could find that one is discharging to charge the other up! I have a kind of experience of this where we have a Solar iBoost as well as the battery; they really don’t work well together. When the batter is discharging, it tends to discharge about 200w more than is needed, presumably so lights don’t dim if we switch something on. This 200w is usually exported but if it’s on, the iBoost sees the 200w, so uses it to heat the hot water tank. The battery thinks “oh, I need to provide another 200w” so increases it’s output and the iBoost soaks it up, so the battery increases by another 200w yada yada ending up with the battery just heating hot water! We’ve had to switch the iBoost off at least until sunnier times.

 

Edit: I suppose I should qualify this by saying you could have multiple batteries behind a single control unit per phase, but as you have a PowerWall I think you can only have one per phase.

Edited December 21, 2021 by Christiano

[joth]

1 hour ago, Christiano said:

I think it’s because it would be a complete nightmare for 2 independent batteries to read your main power line to decide whether to charge or discharge. You could find that one is discharging to charge the other up! I have a kind of experience of this where we have a Solar iBoost as well as the battery; they really don’t work well together. When the batter is discharging, it tends to discharge about 200w more than is needed, presumably so lights don’t dim if we switch something on. This 200w is usually exported but if it’s on, the iBoost sees the 200w, so uses it to heat the hot water tank. The battery thinks “oh, I need to provide another 200w” so increases it’s output and the iBoost soaks it up, so the battery increases by another 200w yada yada ending up with the battery just heating hot water! We’ve had to switch the iBoost off at least until sunnier times.

 

Interesting. My (DIY) PV Immersion redirection also has a 200W export threshold, mostly because my grid import/export monitor (emonpi) only reports the value once per 5s so I need to leave some slack as the natural variation from one second to the next would cause it to spend 50% of the time importing otherwise.

 

You can blind the lower priority device to the higher one by doing fancy tricks with the CT clamps - e.g. if you put the main grid tail plus the battery feed through one clamp then the PV redirect will see everything being exported PLUS everything going into the battery, so will only start to consume power when the sum of them goes below zero (e.g. if the battery is full and PV still exporting)

For your case it's probably the other way around: put the battery's CT clamp around the main meter tail PLUS the feed to the immersion, so the battery controller will see whatever is being exported (aprx 0W) PLUS the 200W the immersion is taking, thus will be satisfied its export threshold is being met and settle into a steady state.

 

Of course doing this in practice, in a regs compliant way, is a exercise for the reader ?

 

 

[Pocster]

3 hours ago, Christiano said:

Our DNO is UK Power Networks, they have useful info on their website (even giving outline costs for certain upgrades like moving power supply, going to 3-phases etc) as I’m sure others do.

My PowerVault battery has 2 inverter settings; 3.68 & 5.5kW. I wanted to have the higher (which is set by the PowerVault mothership) so I had to make a G99 application to the DNO. They gave me permission so long as I fitted an export limiting device (£££s) so the battery can’t export. That’s a bit useless as I got £1k off the battery if I allowed EDF to occasionally force discharge it to help balance the grid.

 

As far as I understand you can only have a single battery per phase. I think it was Robert Llewellyn from Fully Charged who had a Tesla and got a second, free Tesla due to the number of referrals he had but couldn’t put it on until he had 3-phase.

 

I think it’s because it would be a complete nightmare for 2 independent batteries to read your main power line to decide whether to charge or discharge. You could find that one is discharging to charge the other up! I have a kind of experience of this where we have a Solar iBoost as well as the battery; they really don’t work well together. When the batter is discharging, it tends to discharge about 200w more than is needed, presumably so lights don’t dim if we switch something on. This 200w is usually exported but if it’s on, the iBoost sees the 200w, so uses it to heat the hot water tank. The battery thinks “oh, I need to provide another 200w” so increases it’s output and the iBoost soaks it up, so the battery increases by another 200w yada yada ending up with the battery just heating hot water! We’ve had to switch the iBoost off at least until sunnier times.

 

Edit: I suppose I should qualify this by saying you could have multiple batteries behind a single control unit per phase, but as you have a PowerWall I think you can only have one per phase.

Thanks. Not sure that's right for Tesla batteries. You can have 3 per phase AFAIK. If my DNO wants to limit my export I'm happy with that. Can I ask what the "export limit device" cost?. I have managed to get a different company to come and do a survey/inspection they've not quibbled over I am single phase and already have 1 Tesla battery; so assume they don't think that's an issue.

[Christiano]

On 21/12/2021 at 16:01, joth said:

Interesting. My (DIY) PV Immersion redirection also has a 200W export threshold, mostly because my grid import/export monitor (emonpi) only reports the value once per 5s so I need to leave some slack as the natural variation from one second to the next would cause it to spend 50% of the time importing otherwise.

 

You can blind the lower priority device to the higher one by doing fancy tricks with the CT clamps - e.g. if you put the main grid tail plus the battery feed through one clamp then the PV redirect will see everything being exported PLUS everything going into the battery, so will only start to consume power when the sum of them goes below zero (e.g. if the battery is full and PV still exporting)

For your case it's probably the other way around: put the battery's CT clamp around the main meter tail PLUS the feed to the immersion, so the battery controller will see whatever is being exported (aprx 0W) PLUS the 200W the immersion is taking, thus will be satisfied its export threshold is being met and settle into a steady state.

 

Of course doing this in practice, in a regs compliant way, is a exercise for the reader ?

 

 

 

Thanks; I too use emonPi/Tx and had considered trying to use these to switch the power to the iBoost sender on/off but this is a different approach. I think it will be too complex given my already very congested consumer unit cabinet etc. but more food for thought; thanks!

 

On 21/12/2021 at 17:34, pocster said:

Can I ask what the "export limit device" cost?.

 

I had a little google around, it looked like there were devices from AliBaba for £100-200. I don’t need the increased inverter input/output enough to justify this plus paying an electrician to put it in.

Best talk to your new installer and see if they think you need to ask your DNO for permission in the first place.

[Pocster]

4 minutes ago, Christiano said:

I had a little google around, it looked like there were devices from AliBaba for £100-200. I don’t need the increased inverter input/output enough to justify this plus paying an electrician to put it in.

Best talk to your new installer and see if they think you need to ask your DNO for permission in the first place.

Cheers ! New installer out in a week