Grid Voltage too low ~200v

As its getting chilly I decided to turn on our 30A electric AGA this evening. At 2330 when the Intelligent Octopus cheap rate kicks in I've setup the AGA, two 3.6Hybrid inverters (each with a 9.5Kw battery) and my EV charging via an Ohme charger. Looking at the data coming out of Home Assistant I see that my power pull is 16381W and the grid voltage is showing as 206V. Over the last hour or so the voltage has been around the 200V mark. My supply is 100Amp rated and with that V & W the A looks like _80A which is within the limit.
Am I misreading something or do I have a supply issue which needs reporting to the DNO?

Here is an image of the grid voltage

On my Inverter the lower limit is set at 184V. If it's not causing any issue, I would avoid contacting the DNO. Just keep monitoring it, in case it gets worse.

Honestly I am not surprised it dipped that low when you are pulling 16k.5w, judging on just how much 6.5kw drops me when I used to charge my AIO it would drop to around 230, that is a lot of high power stuff you got running at once.

I was a bit surprised that your grid voltage “didn’t keep up” with the demand, but had a look at my own voltage when I was charging both batteries, running the washing machine and dishwasher etc during the 2 hour octopus power up free electricity event we had yesterday

And yep, pretty much the same behaviour, voltage dropped to 207v as I pulled in 10kW

So there you go, the grid isn’t as elastic as I thought it was !

I guess the problem is they can add more generation at a national level, e.g. ask a reservoir to open it's gates, or fire up some coal, but it's hard to balance locally?

Grid taps on transformers can be adjusted manually, but then that's a difficult balance between very sunny days and high demand days.

The grid is very much stable voltage wise. It's the local DNO level and the route between Tx and your house where the voltage drop lies.
You could just have small meter tails or be the end of a long cable run for you to get voltage sag as shown.

Perhaps you could reduce the charging rate of the the 9.5kWh batteries so that they take the full 6 hours to charge. ie around 1.5kW, rather than their full speed. (May be kinder to the batteries too ?)

I had a feeling I'd read that, while your 100A fuse protects your wiring, it doesn't mean you are entitled to all that - contractual limit is around 60A.

207 is the bottom end in the EU and 253 the top end here. Technically any equipment sold in both markets should work in that range.

If it were to go outside of those ranges I’d be asking the DNO to check. Have you considered a small staged startup so the aga heating elements get a chance to warm a bit before you turn on the battery etc?

DD Thats a good idea. I thought about doing the two sequentially but then there is the problem of cross charging/discharging. But sticking with the same fixed time slot 2330-0530 and setting the charge power at 1.5kW looks a much better idea. Thanks

kram I guess that day 1 of turning the AGA on isnt a fair test, after a couple of days to settle down I'll have a better idea of what "normal" looks like. Its the AGA thats the problem for me as its based on a ECO7 model so expects to draw up to 5.5kW/hour for 7 hours versus the 6 hours for Intelligent. I've sort of assumed that after taking 6 hours it would be nearing full and slow down the charge rate when it rolls over into peak rate. Too early to say if thats right. This morning its pulling 20-30minute charges about 2 hours apart trying to get to wherever it thinks is normal. The extra pulls are coming from the batteries of course. I need to get predbat working so I can control this stuff but admit that HA/predbat are pretty complex and I'm at the bottom of the learning curve. Wish me luck!

BarryForde the author of predbat, Trevor, is very helpful, helped me work out how to use it and optimise the settings.
The readme is pretty comprehensive of what you need to set up

And others here can help!

geoffreycoan Thanks for that advice. I was going to shift over to the HA discussions and ask for help there rather than clutter up this one. Its awesome stuff HA and I'm looking forward to the battle!

I've also recently had a grid issue of low volts overnight. I finally convinced UK Power Networks to come out and they are going to fit a volt measuring recorder. My lowest voltage, according to the AIO cloud was just 204v. At this time I was charging the AIO at 6kw, car, ASHP and possibly topping up hot water via immersion, drawing around 14kw in total. But I can pull nearly 18kw during the day and only drop the volts to circa 225v. Doesn't bode well for all of us in the push to an all electric green energy future. I've since limited the AIO to charge at around 4.8kw but still seen below 216v (the lowest guaranteed service) 17 times in the last 6 weeks.

UKPN guy admitted they are now having issues with the network. Network planning I believe used to work on an average house load of around 3kw but as we shift towards an all electric future, it clearly is going to exceed this. Locally in my small network I know of just two ASHP, two car chargers and one house on storage heaters, hence the overnight issue. The local transformer being just 50kw, it clearly can't cope so hopefully it will get upgraded. It serves 19 houses.

Headlines this time in 2034 "National Grid failures cause blackouts over Xmas"

kram the grid specification is 230V -6% to +10% or 216.2V to 253V. If the voltage is below 216.2V then there is an issue somewhere in the system which the DNO is responsible for sorting out.