Low Grid Voltage

[Ultima357]

Hi everyone. Just wondering if anybody has experienced low grid voltage in their supply? I run a self built passive house and have ASHP, solar battery (GivEnergy AIO), car charger etc and being on Octopus Intelligent Go, I have 6 hours of cheap rate overnight electric. My problem is that I can draw as much as 16.5kw whilst on the cheap rate and recently noticed that on these cold nights, the reported grid voltage has dropped to as low as 202vac. I noticed because the car charger dropped out and complained so have been keeping an eye on the situation. 

 

UK power networks unhelpfully told me they could only look when it is happening and to call them at that time which being usually between 2 and 3 am and not every night, is completely impractical. It has for instance only occurred twice in the last 8 days. As peak power pull only occurs when everything kicks in and ASHP is on top power, I can't easily time it, particularly as Octopus control when the car charger kicks in. 

 

My concern is that the low voltage will damage the ASHP and other motors such as fridge compressor as they will pull more current to compensate I believe. Does anyone have any knowledge of this and is it likely to do damage? Any good contacts (email preferably) at UKPN? 

 

 

[MikeGrahamT21]

16kW isn’t really much in the grand scheme of things.

 

I can see it was hanging around 220 @ 10kw which would be just OK, lower end.

 

You are correct, it will pull more amps to make up the wattage (P=IV from memory).

 

Do you have accurate monitoring on multiple devices, just thinking so you can collect lots of data for them. May also be worth speaking to Octopus as they may be able to speak to UKPN and move it along.

 

As for damage, not too sure but most devices in UK are 220-240, so I would assume there’s a possibility there.

 

 

I think it’s normal to dip away a little during load as above, but not as low as you are getting.

 

Theyll likely want you to confirm with smart meter data unless they get that on their end.

[Temp]

I think the spec is +10% to -6% of this nominal value. This means the voltage can range between a maximum of 253 V (+10%) and a minimum of 216.2 V (-6%).

 

Does your smart meter have a way to log the voltage there because that's probably where they will measure it?

 

How about borrowing a load of fan heaters from friends and family to see if you can replicate it in the daytime? Probably need 5 * 3kW heaters. Don't put them all on the same ring!

 

 

[Mattg4321]

Does grid voltage dropping always correlate with the higher load as per the graph in OP?

 

If so I’m going to guess at a high resistance joint somewhere. Could be in your installation (consumer unit main switch maybe), or in DNO’s

[dpmiller]

are you on a pole transformer? Shared?