Zero PV generation allowed by DNO

[willbish]

I made a G59 application with my local DNO to test the water and see how much PV they would let me install.

 

Their response pasted below. My solar guy thinks that if I limit my export to 16A per phase then the DNO may be required to provide the infrastructure upgrade for me. I don't read it like that.

 

Has anyone experienced this before? The 16A per phase is this a discretionary maximum, can the DNO prohibit any generation and/or export?

 

And does it all really matter if i go full DIY and ditch the MCS

What equipment would satisfy the DNO that anything generated is not exported to the grid?

 

 

 

Good morning

 

I have been passed your application for PV Installation at  

Unfortunately there is currently no capacity for generation at this site without considerable reinforcement works which would be chargeable to the customer. Not only will the customer’s own supply and their next door neighbour’s need to be renewed, but a significant stretch of the overhead main will also need upgrading.

 

For clarification this is due to the fact that the overhead conductor is relatively small and also the loading on the network in this area is quite low. The combination of these two factors means that the volt rise caused by the installation of any generation would, at this stage, exceed the permitted limits.

 

Upgrading the conductors to larger ones would enable us to overcome the issue and I can produce a quotation for these works but would advise that it will be roughly in the region of £10,000. Please let me know if the customer would like to proceed with this and I can cost accordingly.

 

Kind regards

[Nickfromwales]

Can the inverter be set to dump to a resistive load to cap the max uplift in local voltage ?

[Guest Alphonsox]

I think that's fairly clear - Give us £10K or you can't export onto our wires. Unfortunately this isn't unusual in more rural areas.

[ProDave]

Now go and propose you are installing a HUGE electric boiler and the voltage DROP will exceed permissible limits and you demand they upgrade their infrastructure.

 

Throw in a non inverter driven heat pump with a huge start up current for good measure.

 

I would be interested of you could get an electrician to measure the loop impedance at the supply point. Or even if you could do a quick and dirty method (I will tell you how if you have an ac volt meter)

[Nickfromwales]

If inverters cut out at 253 volts, what's the issue ? The DNO should be able to provide the provision for that in THEIR infrastructure surely ? 

Wheres the nearest dwelling that would be 'adversely affected' by this uplift, on lines which are good for a lightning strike or 3 bursts of direct short circuit . ?

Sounds like a load of BS to me. 

"Free upgrade" must be their agenda. 

[willbish]

Well they certainly aren't getting 10k from me

52 minutes ago, ProDave said:

Now go and propose you are installing a HUGE electric boiler and the voltage DROP will exceed permissible limits and you demand they upgrade their infrastructure.

 

Throw in a non inverter driven heat pump with a huge start up current for good measure

 

This might be an avenue worth pursuing if I wanted a free upgrade. I will be having an ASHP but i doubt it'll cause a significant voltage drop to concern the DNO. Do I really need an upgrade

 

I dont want to export any of PV anyway so is all of this a bit pointless? Can I just get on and DIY install as much PV as I can afford and have a way to satisfy the DNO that nothing will be exported?

[readiescards]

I had to get the ashp approved by the DNO to ensure no infrastructure upgrades would be needed, with the implication being I would need to pay

[joe90]

7 minutes ago, readiescards said:

I had to get the ashp approved by the DNO to ensure no infrastructure upgrades would be needed, with the implication being I would need to pay

 

I too was told I had to inform the DNO of my heat pump but not anything else that uses high current. Most good ASHP,s are Inverter driven so the initial load ( the DNO,s perceived problem) is not a problem and creates less initial load than say a 10Kw shower. I did not inform the DNO ?.

[SteamyTea]

2 hours ago, Nickfromwales said:

Sounds like a load of BS to me. 

It isn't.  They have had the right to either refuse connection or ask for an upgrade payment since before the FiTs system came into force.

it is not always used, but it is done for good reasons about grid stability.

1 hour ago, willbish said:

I dont want to export any of PV anyway so is all of this a bit pointless? Can I just get on and DIY install as much PV as I can afford and have a way to satisfy the DNO that nothing will be exported?

Then design an off grid system. There are 'islanding' systems that can deliver power when there is a power cut, just a modification of that really i.e. as soon as you are generation you automatically disconnect from the grid.  It will need storage, which s expensive, and approval from your DNO for safety reasons.

So probably easier to just run a local off grid storage system that runs a few appliances.

2 hours ago, ProDave said:

Now go and propose you are installing a HUGE electric boiler and the voltage DROP will exceed permissible limits and you demand they upgrade their infrastructure.

It might blow the company fuse.

1 hour ago, willbish said:

I will be having an ASHP but i doubt it'll cause a significant voltage drop to concern the DNO. Do I really need an upgrade

There have been cases where HPs have been refused,  SarahSW from eBuild had hers refused (though I think that she abandoned her project in the end if it is the old church I frequent pass).

[Nickfromwales]

2 hours ago, willbish said:

I dont want to export any of PV anyway so is all of this a bit pointless? Can I just get on and DIY install as much PV as I can afford and have a way to satisfy the DNO that nothing will be exported?

You may want to go mostly DC array then, with the Sunamps having an option to be pre-loaded with DC immersions instead of AC ones.

According to the bumf, the DC system is around ( iirc ) 13-14% more efficient at driving the Sunamps ( or other DC load ) than going via an inverter. 

Say for eg the array is split 75% DC and 25% AC with micro inverters and you'll be able to demonstrate very minimal max export. 

If the PV is driving / fortifying an electric only based space heating and DHW setup ( as you are ) then just go all DC, but I'd prob prefer a bit of AC to at least offset your known base / vampire loads so when the SA units max out you can still utilise the sun to some other extent. 

[Nickfromwales]

1 hour ago, SteamyTea said:

It isn't.  They have had the right to either refuse connection or ask for an upgrade payment since before the FiTs system came into force.

it is not always used, but it is done for good reasons about grid stability.

If it was a sizeable development site then I may agree, but for one property on an end-of-line overhead supply ? Surely reinforcing the grid with exported energy, there at the end of the line and from only one property, would decrease the load on the upstream infrastructure?

Tell the next person, or the one after that "no", but there should be an allowance for at least one exporter there, even if it's first come first served. 

[dpmiller]

Dave makes good points re. the loop impedance and I'd be querying of the DNO what their tolerances are if a mere 4kW is enough to push the supply ABOVE spec. Considering that both you and your neighbour will be on (eg) 80A fuses, so 18kW each...

 

NIE for example quote 230v, but -6% and +10%.

[Dee J]

Given that the sub 4kw G83 installs only require notification after commissioning, how would the DNO deal with that situation? Tell you to disconnect an already functional system?

[SteamyTea]

40 minutes ago, Dee J said:

Given that the sub 4kw G83 installs only require notification after commissioning, how would the DNO deal with that situation? Tell you to disconnect an already functional system?

Yes they can, and have done.

When I was working for a dodgy PV company, they had fitted a 4kW system on a farm.  The DNO asked us to disconnect it until they had checked the local transformer.  In all fairness to Western Power, they dealt with it all within a few days.

 

It has to be remembered that the power grid was designed as a centralised power network, not a distributed one, so you can't have every Tom, Dick or Harry hanging whatever they like on the system.  Do that and you get an American or Australian type system that fails frequently.

Or to bring it closer to home, imagine a single spur on your house, you would not try to to overload it as you now that the fuse will pop, or if you put in a larger fuse, the wiring will catch fire.

[Dee J]

1 minute ago, SteamyTea said:

Yes they can, and have done.

When I was working for a dodgy PV company, they had fitted a 4kW system on a farm.  The DNO asked us to disconnect it until they had checked the local transformer.  In all fairness to Western Power, they dealt with it all within a few days.

 

It has to be remembered that the power grid was designed as a centralised power network, not a distributed one, so you can't have every Tom, Dick or Harry hanging whatever they like on the system.  Do that and you get an American or Australian type system that fails frequently.

Or to bring it closer to home, imagine a single spur on your house, you would not try to to overload it as you now that the fuse will pop, or if you put in a larger fuse, the wiring will catch fire.

Well I hadn't heard that before... seems logical that the DNO has the final say. Although I'm surprised that a full 4kw export (assuming zero local load) has the power to push the local network out of spec, especially considering the G83 failsafes.

[SteamyTea]

In rural areas, with non standard diversity (usage patterns), and an old infrastructure, they potential can cause a problem.

Trouble is that a fault can pass back up the line and cause a bigger fault somewhere else.

 

Down here during the micro generation boom, there was a warning sent out the local grid was at saturation in some places and no more microgeneration was going to be allowed.

[Nickfromwales]

10 minutes ago, Dee J said:

Well I hadn't heard that before... seems logical that the DNO has the final say. Although I'm surprised that a full 4kw export (assuming zero local load) has the power to push the local network out of spec, especially considering the G83 failsafes.

Yes, particularly as it'll be rarely operating at 100%, and it'll be less self consumption.

[SteamyTea]

The problem is that the worse cases have to be taken into consideration, not the norm.

 

We would all get a bit pissed off if every time the sun came out from behind a cloud, the electricity failed.  Especially if you had just fitted a PV system.

[Nickfromwales]

1 minute ago, SteamyTea said:

In rural areas, with non standard diversity (usage patterns), and an old infrastructure, they potential can cause a problem.

Trouble is that a fault can pass back up the line and cause a bigger fault somewhere else.

 

Down here during the micro generation boom, there was a warning sent out the local grid was at saturation in some places and no more microgeneration was going to be allowed.

Shouldn't that have read, and no more micro generation was going to be allowed until the government acted to enforce that the necessary upgrades would be made mandatory eg the 'poor' energy companies would have to plough some of our money back into maintaining and upgrading the network that allows them to charge us what they do?

How many decades has some of the rural stuff been in, eg where they should ( imo ) be upgraded in line with local growth / development rather than charge for the pleasure?

I still fail to see how local micro-generation, sub 253v, could affect the upstream system as most would be consumed by the ( non-generating ) neighbours anyway, and how much excess could a couple of <4kw arrays produce after self-consumption anyway?

 

2 hours ago, dpmiller said:

Considering that both you and your neighbour will be on (eg) 80A fuses, so 18kW each...

Majority of rural properties will be on a 60a supply. I went to one house by Swansea airport which was on a 60a supply fuse, had a huge induction hob, double fan assisted oven, full kitchen of appliances and white goods, ( no gas ), 3 electric showers ( one was a 10.5kW ), and another all electric kitchen in the above garage granny annex, which was on its own CU fed ( split ) from the house 60a supply !! There fuse wire must have been glowing in the dark. 

 

1 minute ago, SteamyTea said:

The problem is that the worse cases have to be taken into consideration, not the norm.

 

We would all get a bit pissed off if every time the sun came out from behind a cloud, the electricity failed.  Especially if you had just fitted a PV system.

Agreed, but instead of just knee-jerk responses to these problems they should carry out actual local surveys to work out the worst case, and if it wasn't that problematic then the install should be able to go ahead ( as per my previous ) eg first come first served, where I may get PV this week but next week my neighbour wouldn't. You still have to go to war with them about inverter driven heat pumps FFS, but fitting a new big electric shower.....not a problem  

[SteamyTea]

18 minutes ago, Nickfromwales said:

but instead of just knee-jerk responses to these problems they should carry out actual local surveys to work out the worst case

They do.  They have a big database of what is where and what it is capable of (the database was designed by an old girlfriend of mine, should have stuck with her as she sold her company for 5mil).

The DNOs don't give too hoot about what you connect, all they are concerned about is keeping the network going, as that is their job.

21 minutes ago, Nickfromwales said:

Shouldn't that have read

Then you are into politics.  I don't hear many people saying that we should go back to mid 1970's income tax rates i.e. 500 quid tax free allowance and starting rate of 33%.

What I hear is that people want more FiT money, and you are going to pay me it.

[Nickfromwales]

5 minutes ago, SteamyTea said:

people want more FiT money, and you are going to pay me it.

And there lies the problem. Most fitted these in the early days out of mostly greed and being ABLE to afford it. They are going to be better off than most for a lot longer. 

Instead of a FiT, there should have been subsidies and grants to fit a couple of panels to every home, just to offset the consumption at each dwelling, and to reinforce the localised grid areas. 

That would have benefited the grid and at the same time encouraged ( forced ) them to upgrade their infrastructure accordingly. 

Nothings free I know, but its not exactly a charity, this electricity transportation lark, now is it   ?

 

9 minutes ago, SteamyTea said:

an old girlfriend of mine, should have stuck with her as she sold her company for 5mil

She looking for a toy boy by any chance?

[SteamyTea]

42 minutes ago, Nickfromwales said:

She looking for a toy boy by any chance

You plumbers always like old pipes, dirty bugger.

[billt]

1 hour ago, Nickfromwales said:

Most fitted these in the early days out of mostly greed and being ABLE to afford it. They are going to be better off than most for a lot longer.

 

A person could take exception to that remark. We had a system fitted in 2011, the main motivation was my long term interest in PV and other forms of semi-self sufficiency in energy. A FIT supported system was the only economically feasible way of doing it at the time - the subsequent collapse in PV system prices was unforeseen.

 

The economics aren't actually that good. The FIT will have paid the capital cost of this system in another 2 years, so 9 years from installation. The loss of interest etc will take another year or so to recover. After that it should be providing an income for another 15 years, but it's a very long term investment and we probably won't be getting the income.

 

Actually, I don't disagree with your comment. All the renewable incentive schemes have been ill conceived and badly implemented; FITs should have been reduced much sooner and phased out completely by now; the RHI was a nonsense from the start.

[willbish]

11 hours ago, Nickfromwales said:

You may want to go mostly DC array then, with the Sunamps having an option to be pre-loaded with DC immersions instead of AC ones.

According to the bumf, the DC system is around ( iirc ) 13-14% more efficient at driving the Sunamps ( or other DC load ) than going via an inverter. 

 

 

11 hours ago, Nickfromwales said:

just go all DC

I like the  sound of this, greater efficiency, cheaper install cost as no inverters required.

 

Would be concerned about over sizing the array. With storage (sunamp) up to capacity too early on a bright sunny day and potential generation being wasted. And therefore increased payback time of the PV hardware.

 

I was expecting to size my array based on limitations of roof area first, then amount I could afford, then any DNO limitation.. Think I'm going have to give this some careful consideration to get it just right.

 

So if I only have a DC set up what else could I power once the Sunamp is topped up? I guess nothing domestic other than an electric vehicle, which is probably a few years away for me. Even then would I need two charging stations..

[willbish]

4 hours ago, dpmiller said:

Dave makes good points re. the loop impedance and I'd be querying of the DNO what their tolerances are if a mere 4kW is enough to push the supply ABOVE spec. Considering that both you and your neighbour will be on (eg) 80A fuses, so 18kW each...

 

NIE for example quote 230v, but -6% and +10%.

 

Will quiz the DNO on this and let you know their response. I am also awaiting a quote from them to bring the supply in through a duct. Have also asked for a 3-phase quote, reckoning that'll be crazy money judging by their perceived state of the local infrastructure.