My Toaster says "Voltage Too High, Please Make Other Toast Arrangements"

Yes it's happening, smart devices are diagnosing your problems and bowing out of service and more frequently this is because of high delivered voltage, 230+10% = 253V! The irony of course is that if they weren't so trigger happy and kept going, then on a national level, there might even be enough load to pull the voltage down.

UK standards 230V +10%/-6%, 216.2V to 253V. (BS 7697:1993)
UK standards 230V +10%/-10%, 207V to 253V. (BS EN 60038:2011)
EU standards 230V +10%/-10%, 207V to 253V for 95% of the time.  (EN50160)

If you are experiencing high voltage, then you are likely to have PV generation on-site or near by. As the sun rises and your solar panels start to generate the inverter will raise its voltage to service the loads in your property, to achieve this it will surpass your delivered voltage from your energy provider. Once all your loads are serviced and the solar system has more energy to produce it will start to export this energy to the grid and the only way it can do that is to raise its voltage above your delivered grid voltage. 

We recently surveyed two neighbouring (detached) properties with some EC-1V single phase voltage recorders, one property with solar PV the other without. The PV property had a voltage difference of +1V to +6V, during periods of solar generating/exporting, +3V being the most frequent difference. So clearly the solar is having an effect.

If should be remembered that a voltage difference between properties is normal as loads are switched on and off in each property. The problem here is that high voltages are being generated during the day when homeowners are not at home, late morning to late afternoon, so there is reduced loads and to compound this all the local PV stations are generating and possibly exporting, simultaneously.

A local network on shared transformer that was once configured (tapped up) so that all the property as loads would have the correct voltage in cold, dark December, now has reduced loading as the PV properties are servicing their own loads and if they are exporting power into the same local network, this will further reduce the load on the transformer, which only has one effect, to allow the voltage to rise.

So where are we heading, high voltage during warm sunny days and low voltage during off peak (EV charging) and dark, cold winter nights.  Is an unmanaged 207V to 253V too tight?