Smallholders Insurance from Greenlands

Author Topic: Solar PV inverters and Over Voltage problems in rural areas  (Read 3192 times)


  • Joined Mar 2012
  • Carmarthenshire/Pembrokeshire Borders
Solar PV inverters and Over Voltage problems in rural areas
« on: April 26, 2022, 08:54:21 am »
Just polling for information from those fellow smallholders in rural areas with solar PV systems.

We are out in West Wales on the borders of Pembrokeshire and had our solar PV system installed almost 7 years ago and it had worked without any problems until mid February. (Well, inverter failed and was replaced under warranty 3 years ago but that was a fairly painless process).

However, since mid Feb (around the time of power cuts and storms) the inverter started generating alarms due to it "seeing" an over voltage on the grid (the cut-off point is 260volts) that has gotten steadily worse to the point where it would cut out by about 9.30 in the morning and not come back online until late afternoon! With our weather recently this represents a loss of up to 20KwH per day and with the price of electricity a serious problem.

Obviously we reported this to the installer who claims the device is working as designed (?) and it was down to Western Power who were allowing high voltages on the grid. Now I am no electricity grid expert, but when the logs from the device are recording grid voltages at  times exceeding 270 volts I would expect our TV, fridges, computers and just about everything else to have blown up with those sort of voltages. Western Power were as efficient as ever and arrived within a few hours and installed a voltage logging device. A week later it was removed and they sent me through the results - average voltage 243volts and at no time did it go over 248 volts, even when the inverter was showing the grid voltage at 270volts.  Call me simplistic but in my book that means the inverter is failing, probably due to thermal failure and degradation in the voltage sensing circuits.

Sent all the information to the installer and still got a snotty response to the effect that they had passed it all on to the inverter manufacturer (Solis) who had interrogated the device remotely and confirmed everything was fine so they were not going to replace it under warranty. The installer (EEC Solar in Southport) were very efficient in the early days but now I am prepared to give up on them, despite the fact they have a 20 year warranty on the system. At the end of the day, a warranty is only as good as the company behind it.

My question is this:

Does anyone else have similar problems with their inverter and over voltages in rural areas where the power lines are longer than normal so voltages may be higher to account for transmission losses? What inverter do you have? Tried a couple of local firms but they are all claiming to be so busy they really don't want to know.

I think I will either have to take EEC Solar to court (Sale of Goods Act?) or bite the bullet and buy a new inverter myself unless I can find a way to fix this.

Any experiences gratefully received.


  • Joined Mar 2009
  • carmarthenshire
Re: Solar PV inverters and Over Voltage problems in rural areas
« Reply #1 on: April 26, 2022, 09:29:10 am »
Not exactly what you’re asking for but if WPD have found their voltage to be below 253v then they are probably in the clear. I'm guessing they checked the voltage at or near the origin - at the meter?

If the inverter is set to UK spec in its settings, it should keep pushing all the way up to 264v IIRC.

If it is showing 270v then it's either been calibrated very badly or there could be a poor connection between the inverter and the origin of the electrical installation.

If you can get the inverter to display grid voltage when it isn't actively inverting, or it's dull, then see how that compares with WPD figures. If it's still higher then that suggests faulty calibration of the inverter; if it broadly agrees with WPD figures, then that suggests a poor connection between the inverter and grid. How far is the inverter from the origin?

If you have a voltmeter and it's sunny try measuring the volts as close to the inverter as you can get. Do the same as close to the origin as you can get.[size=78%]You should be able to see variations of a few volts. The variations at the inverter should be greater when the inverter kicks in, or out, but only by a few volts.[/size]


  • Joined Dec 2011
  • Gascony, France
Re: Solar PV inverters and Over Voltage problems in rural areas
« Reply #2 on: April 26, 2022, 09:39:33 am »
You can buy (cheaply) a power monitor that plugs into a socket and that will tell you what the voltage is. You can also plug a device into it and it will tell you the instantaneous load and the energy used within the monitoring period. We have one and very useful it is, despite needing French socket adaptors both sides.

One of the two parties isn't right and it sounds like the inverter manufacturer, but you won't know until you have checked it yourself. From memory the voltage tolerance is about 2%- here it's more like 10%, because a 220V device can be given 250V (measured in the Dordogne) but will still work at 220V. Generally the voltage here is 240V. The main supply cable has been replaced recently (they are all overhead lines) and they don't make any allowance for voltage drop in the cabling- we're all fed from the same transformer point and we are at the end. If anything, our voltage should be low.


  • Joined Mar 2009
  • carmarthenshire
Re: Solar PV inverters and Over Voltage problems in rural areas
« Reply #3 on: April 26, 2022, 10:08:04 am »
In the UK the requirement is 230v +10%, -6%. It used to be 240v +-6% before we harmonised with Europe. But i n the UK the inverter is allowed to keep going up to 264v (on the Netherlands setting they shut down at 253v)

In practice a lot of rural supplies are still unmodified, and are only updated if someone lets the network operator know it's our of spec. But in this case that seems to have been ruled out so it's either the inverter or it's connection to the grid.


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