Help! Solar PV connected to a very long distance 230V supply

[JamesL503]

We're in the final stages of installing solar PV at home, only to be hit with a technical snag... We're probably the last house in Western Power Distribution's network, and our 230V supply comes 1300m from the transformer, shared with three other properties. When we moved in 14 years ago we complained about low voltage (160V or less at times) and they installed a load balancer at the house end. So we have 3 phases to the last electricity pole, then single phase to the house from the load balancer (10m or so) as single phase. Apparently the load balancer pulls power from each / all of the three phases to make up the single phase to the house. WPD have refuse outright to approve a 7.5kW installation as they reckon it will blow their overvoltage tolerance. Nb this isn't the statutory 230V + 10%, but +1.5% over some datum which for the moment they can't define... They admit we can install 3.6kW, but advise that it could still trip their +1.5% datum, and also could blow the load balancer. So, please can anyone advise, eg: - What's the datum for the +1.5%? - What's the chance of our tripping the +1.5% off a 3.6kW installation - I'm assuming they must measure it at the transformer, ie 1300m away? I think that most of our 3.6kW is going to disappear in resistive losses back to the grid! - What's the chance of us knackering the load balancer? - Anything else?? They're also thinking of moaning about allowing PV connections to properties which have been the subject of a voltage complaint - not sure where to go with that one yet, but if anyone has any experience in the area please say! Thanks in advance, James

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[SolarCity]

As far as I am aware, you can connect your system at 3.6kWp and then it is up to the DNO to decide how they counter their problems.

In short, it's not your problem.

 

[BruceB]

I'd be surprised if you get substantially different answers here from where you first asked the question but we'll see!

 

[JamesL503]

I'd be surprised if you get substantially different answers here from where you first asked the question but we'll see!

Well, all contributions are gratefully received!

Followng some of the suggestions over on Navitron I ran some tests last night. Loading the house up progressively with a couple of 2kW electric fires caused a 2V per kW fall in voltage. So by implication, 3.68kW of PV in ought to increase the voltage by 8-9V or say 4% in the house. The supply to the house seems to be at about the 240 - 245V mark (it varies), so 3.68kW of PV ought to give us 249 - 254V in the house - presumably until WPD get round to turning the current 240V down to 230V. And surely 254V won't blow the balancer?

We also tested the voltage when next door's nightstores come on on Economy 7 - really interesting. When the lights go dim leap out of bed and take the voltage, to find it's 238V and climbing - very quickly gets back to 240V. So the load balancer seems to be doing its job, even though the neighbour's supply is upstream of the balancer, tapped into one phase only.

I'm very tempted to go for it - there seems to be a lot of variation in the voltage down here anyway, and my gut feel is that our 3.68kW will get split between the three incoming phases. WPD may end up tweaking their transformer settings over the hill, but surely no more than seasonal variations?

As I say, all thoughts very welcome and many thanks so far!

James

 

[BruceB]

[FONT=&quot]I am intrigued [/FONT]by this load balancer if anyone has any links to details online.

 

[Earthstore]

Here is how I see it.
If your supply has run within tolerance (although unstable) since the DNO fitted this stabiliser and then you fit your PV and it keeps tripping or pops the supply, they are going to blame your PV, I have a friend who works for the DNO and I know that it is already a problem to them.
That said, it is only a small system so should not be a problem really.
Have a look at a thing called a voltage optimiser, which can stabilise the incoming supply to your house to 220 v, this may help?
My advise, fit the system, but be aware that you may have problems, and the DNO may blame your system..
Hope this helps.

 

[BruceB]

Earthstore, If you are thinking of something like the VPhase voltage optimiser, then you cannot connect PV to the load side of these (if that is what you are suggesting).

 

[JamesL503]

Hi, thanks for that. I think I'm relaxed about the effect on the house, I'm more concerned about the effect on the feed. Does anyone know what WPD are referring to when they moan about 1.5% overvoltage? What's the datum?

J

 

[Graeme Harrold]

As far as I see it, I agree with Solarcity, if you had not applied for the G59 you would have not known. Connect 3.6 under G83 and pass the ball back to the DNO. On the Scottish Power modeling, I shouldnt have my install, as I asked to extend to 8kW. Scottish Powers answer was "you can connect under G83, our hands are tied"

Crack on and use the G83 connection rules to your advantage......It may force your DNO into providing a more stable solution to your (and neighbors) supply.

 

[Earthstore]

Sorry BruceB, I was not suggesting anything, just making a suggestion for them to research, however, I have since found this link which says you can connect with solar PV. Vphase Solar PV Panels Installations

I hope this is of some help.

 

[danesol]

BTW...... Western Power tolerances are actually +10 / - 6% on 230vAC AFAIK


EDIT:- Any voltage less than 217vAC I would say all you electrical appliances will be subject to the "brownout effect" and will all give in at somepoint - note down any failures of appliances and record weekly/daily income voltages at the samtime as the DNO will be fully responsible for replacing all items damaged by undervoltage.

hth

 

[BruceB]

Yes you can connect it alongside solar pv, but the pv cannot be on the load side of the VPhase. Some people had considered that as a way of overcoming voltage drop issues, but you cannot send power backwards through the Vphase.