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Grid tied inverters will result in high mains voltages above 300VAC..do you agree?

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treez

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When a grid tied inverter (from a solar fed battery) is connected to the mains, it senses the mains voltage and disconnects if the mains voltage goes above 250VAC in UK (above 240VAC in Europe). However, the disconnection is not instantaneous, there is a slight delay. Therefore, it goes without saying that if multiple grid tied inverters are connected to the mains, then if the loads on the mains suddenly reduce, then the mains voltage will obviously shoot up significantly….voltages above 300VAC would surely not be unrealistic. A grid tied inverter cannot predict the future. Surely you agree?
 

Not particularly a problem of grid tied inverters. You observe different levels of short term overvoltages and surges in the grid. For a serious discussion, you need to analyze grid impedances and characteristic of connected devices.

What time range of overvoltages are you considering?
 
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I believe the overvoltages would be more common over short time ranges of up to 10 milliseconds or so.....because the GTIs would quickly sense the overvoltage and turn off.
 

a peak voltage sense of 365Vpk or so would be fast enough to shut off an inverter in a few uS. However, even 20mS of 300Vac will not damage the vast majority of mains connected devices ...
 
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Thanks, I actually wonder where the threshold is set for turn OFF of an inverter….i mean, “normal” mains voltage is permitted to go up to 265VAC anyway…that’s 373vpk…..so any inverter would not be allowed to trip on a voltage up to 373v I would have thought. The threshold would have to be set higher than 373V….then due to noise on the comparator input, you’d probably add say 10V on to that (to avoid spurious tripping , ie spurious turn off of the inverter)….call it 383v trip threshold………..so it does appear that areas of mains phases where there are lots of inverters connected, will almost certainly see a higher mains voltage……..potentially up to 265VAC? That is 265VAC potentially all the time?
 

All the grid tied inverters I have designed would be off above 245Vac - there's really no point them being on - after all there is plenty of mains coming from somewhere else...
 

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