DNO rule change

[Pocster]

I see since April 1st DNO rule changes have been applied that infrastructure improvements may not be passed directly onto the customer 

 

https://ukpowersolutions.co.uk/2023/02/14/changes-to-electricity-connection-charges/

 

This means that maybe I can have another PW but with an export limit 😊 ; makes octopus flux look even better …

Edited May 1, 2023 by pocster

[ProDave]

I am waiting to hear of applicants post April to see how it works in practice.

 

If indeed it appears the customer no longer has to pay for perceived network upgrades then I might be tempted to apply for more PV.  they made it pretty clear last time that if I went 1W over 3.68kW there would be a network upgrade charge.

 

I would like a second PV system with batteries so in theory it would not export anything but I don't even think they allow you to say "but it won't export anything" i still believe they think it might export up to the inverters limit.

[Pocster]

6 minutes ago, ProDave said:

I am waiting to hear of applicants post April to see how it works in practice.

 

If indeed it appears the customer no longer has to pay for perceived network upgrades then I might be tempted to apply for more PV.  they made it pretty clear last time that if I went 1W over 3.68kW there would be a network upgrade charge.

 

I would like a second PV system with batteries so in theory it would not export anything but I don't even think they allow you to say "but it won't export anything" i still believe they think it might export up to the inverters limit.

Yeah I’m not convinced. But in theory DNO’s are going to have more difficulty rejecting ( or limiting ) things . I’m certainly looking into it . I *presume* also I could apply to increase by export limit of 3.66kwh .

They gave me a merry dance last time - so will see what they say ….

[Dillsue]

We added a second 3.68kw PV system last year to give 7.4kw max export and our DNO didnt charge for a transformer upgrade. I suspect it was because the original transformer was undersized by today's standards, but they could have asked for something towards it???

 

@pocsterId have thought youd be able to get more than the 3.68kw G98 limit fairly easy?? You in the middle of nowhere fed by a bit 2.5 twin and earth?

[Dillsue]

The table near the beginning of that linked doc says increased capacity upgrades are free. Guess there may be a bit of a wait but should be able to export what you want, in time. Took our DNO best part of a year to upgrade our transformer, but they did make a bit of a meal of it with new poles/cables etc.

[Kelvin]

Good news. 

Edited May 2, 2023 by Kelvin

[Pocster]

7 hours ago, Dillsue said:

We added a second 3.68kw PV system last year to give 7.4kw max export and our DNO didnt charge for a transformer upgrade. I suspect it was because the original transformer was undersized by today's standards, but they could have asked for something towards it???

 

@pocsterId have thought youd be able to get more than the 3.68kw G98 limit fairly easy?? You in the middle of nowhere fed by a bit 2.5 twin and earth?

No . Right in a suburban area ! . DNO just wouldn’t allow due to infrastructure upgrades required ( apparently ) . But now ! - now I got them 😁

[ProDave]

39 minutes ago, pocster said:

No . Right in a suburban area ! . DNO just wouldn’t allow due to infrastructure upgrades required ( apparently ) . But now ! - now I got them 😁

Dolet us know their responde.  A lot of us are waiting to pounce on the DNO for higher export limit.

[Pocster]

Somethings not right .

Heres the original reason for refusal 

 

I’��m afraid we are unable to permit the installation of any additional generation at this property. The customer already has a significant export capacity (8.6kW) and therefore any additions to this would result in their volts (and those of their neighbours) being extremely high and certainly outside of statutory limits.

Whilst in this instance the customer is on a lightly loaded LV main, fairly remote from the substation (both of which contribute to volt rise), I am yet to see an application of this size which can be permitted. Having almost 14kW of generator capacity on a single phase supply will always result in very high volts due to the imbalance created on the three phase network therefore is unlikely to be approved in any scenario.

[ProDave]

What they are saying is the cable or transformer is inadequate and needs upgraded.

 

Personally I am forming the opinion if I do add extra solar I just won't tell anybody.  I export almost nothing from what I have and the same would be true of any addition (with batteries)

[Pocster]

15 minutes ago, ProDave said:

What they are saying is the cable or transformer is inadequate and needs upgraded.

 

Personally I am forming the opinion if I do add extra solar I just won't tell anybody.  I export almost nothing from what I have and the same would be true of any addition (with batteries)

Yeah . So it’s an infrastructure upgrade required . So dno’s responsibility to do now ?

[Pocster]

So the issue is raised voltage due to another ac inverter .

No device that can limit this ?

[ProDave]

No, though some inverters you can adjust the voltage at which they trip or cut out.  But that just hides the problem not cures it.

 

But if you really are self using and not exporting much it is a non issue and like my situation, becomes a load of theoretical nonsense.

[Radian]

4 hours ago, pocster said:

So the issue is raised voltage due to another ac inverter .

No device that can limit this ?

In order to push the amount of power you would like to push into the grid, your inverter(s) have to raise the voltage at your connection. People nearby will have that extra voltage appearing at their connections too.

[Pocster]

Just now, Radian said:

In order to push the amount of power you would like to push into the grid, your inverter(s) have to raise the voltage at your connection. People nearby will have that extra voltage appearing at their connections too.

Got ya 

Those new DNO rules only seem to apply to new connections forcing infrastructure upgrades . So I’m out of luck there . But ! I’m so far from my sub station apparently ( adding to the issues ) that I guess in time a new development could appear forcing the necessary upgrade .

[Pocster]

3 minutes ago, Radian said:

People nearby will have that extra voltage appearing at their connections too

I don’t care about my neighbors 😊

[Radian]

1 minute ago, pocster said:

I don’t care about my neighbors 😊

Sure thing Vladimir, but the DNO does!

[ProDave]

So why can't the DNO say go ahead export as much as you like, but your inverter may trip on over voltage.  

 

That is after all what that function is there for.

 

It would allow people like me who have no intention to export anything to fit more PV for self use, and if things go wrong and too much accidentally tries to export the inverter voltage limit would stop it overloading the network.

[Johnnyt]

I at times export at nearly 252 volts causing my neighbours EV charger to trip out for overvoltage.

The transformer is 150m away with only 2 properties fed of a 185mm cable .

My array is 10kWp via a 6kW inverter.

I remember when looking at PV several installers tried to sell me "witchcraft" voltage optimisers.

Could these be not used to regulate voltage for export?

[SteamyTea]

17 hours ago, Johnnyt said:

I at times export at nearly 252 volts causing my neighbours EV charger to trip out for overvoltage.

The transformer is 150m away with only 2 properties fed of a 185mm cable .

My array is 10kWp via a 6kW inverter.

Not surprising that it hits the upper voltage limit when the modules and inverter are that mismatched.

 

[Carrerahill]

17 hours ago, Johnnyt said:

My array is 10kWp via a 6kW inverter.

 

I can see the benefits of this in the winter, but it seems quite a mismatch at about 66% over, typically PV oversizing is usually about 20% - this is not an industry standard but a common figure quoted in the industry. 

 

I would expect on a good sunny day you will be clipping a lot (lots of heat in the inverter - not good for it) and wasting a load of generated power.

 

I think I would be upgrading your inverter to about an 8kW unit - get one with a reasonably low start voltage and you won't lose out on much on a grey day.

Edited May 3, 2023 by Carrerahill

[Johnnyt]

It’s solar edge dc coupled to 10kWh battery soon to be 20kWh.

Excess PV goes uninverted direct to battery. SE allow 200% oversize with battery.

I’ve seen the array generate 8kW  with 5kW going to battery and balance to serve house load.

I also have dhw divert

This is from last August.

Quite a handy feature of dc coupling.

[Dillsue]

On 03/05/2023 at 13:30, Carrerahill said:

I can see the benefits of this in the winter, but it seems quite a mismatch at about 66% over, typically PV oversizing is usually about 20% - this is not an industry standard but a common figure quoted in the industry.

Solaredge allow significantly more oversizing than 20% with a 3.6kw SE3680H accepting up to 5.7kw DC input which is 55% oversizing. Split the panels over differing compass points and you can have much more.