Updated: 5th May 2023
We’ve looked at the noise that comes from a tracking solar panel, and we were asked about the inverters. So here goes…
What is an inverter?
When a solar panel produces electricity it is in a DC current. In order to convert it into an AC current (like we use in our homes) it must be inverted. And in it’s simplest form that is what an inverter does.
In utility-scale solar farms (like Enso Energy & EDF Renewables) these inverters are stored inside large shipping containers. And these shipping containers are dotted around the site, taking in the DC electricity from the solar panels.
What information do we have?
Neither Enso Energy, EDF Renewables nor Statkraft have released details on the inverter technology they will using. Enso Energy have stated that at this time they do not know what technology will be used. However interestingly, Enso Energy were able to submit noise ratings for their noise analysis(!) so we have a little information, even if it is completely bogus because they don’t know what technology they will be using.
In the Enso Energy noise report it states that at a distance of 10m from the inverter, the noise level during the day will be 59dB, and during the night it will 49dB. Inverters apparently operate at a lower duty during the night time when the solar panels aren’t producing energy, which seems logical. According to their comparison chart this is similar to being “Inside a car” (we presume while it’s actually moving at speed), to a “Typical Office”.
And that sounds like….?
Yeah it doesn’t really give you much of an idea what it sounds like does it.
So we’ve found this video recording the sound of an inverter. We appreciate that this probably won’t be the exact same model that the developers here will use, but they won’t tell us that, so this will have to do for now. We believe at the end the man talking says “but they don’t get too loud.”
We have also been sent this link to another inverter on a solar farm in the UK where the recording is taken from an adjacent public footpath.
Conclusion
Enso Energy, EDF Renewables, and Statkraft will all have multiple inverters dotted around the site. And they seem to have located most of them towards the edges of fields and adjacent to the public footpaths. They seem to say that this is so they are away from residential houses, which is kind of them, but all of the ones adjacent to the public footpaths could have been located further away and still not be near a home.
The inverters will be working continuously throughout the life of the project. That is 40 years for Enso Energy, and 35 years for EDF Renewables and Statkraft.
The Enso Energy noise report states that the noise from the solar farm is “likely to have a low impact”, but the baseline* recordings weren’t taken across the full spectrum of the site. They were taken near the likely noisiest points of the site and used as a baseline across the whole site. The typical noise level along a public footpath (almost nothing) won’t be the same as that next to a house full of people. Especially on warm summer days like when the recordings were taken in July.
*The term “baseline” simply refers to the starting point. i.e. what the noise level is like now.
You may not be standing quite this close to an inverter, but we all know how far noise travels in these wide open landscapes.
How does the noise from this inverter compare to the noise you hear outside now? Would you agree with “low impact”?
I thought there would be a bit of a humm
Drives you crazy – especially at night , they may be less noisy at night but will sound louder because the surroundings are quieter, So this is the noise the inverters make when in a shed/cabinet – EDF although they are asking for planning permission for portacabin like enclosures for inverters , they hope not to use them, their preferred technology is a String Inverter (so they wont be installing what they asked for). So these String Inverters are ‘strung to the back of the solar arrays – no case/ no enclosure what do these sound like , are their more of them? not very much information has been forth coming – , and no they have no noise monitoring information available .
Drives us crazy – what about the animals – bats trying to navigate and feed, owls trying to forage – do EDF offer any research or information on the effects of this noise on these , on our wildlife ? No
If EDF seek planning permission for inverters to be contained within specific units, but install string inverters instead then this may be considered a breach of their planning permission. It is something to keep a close eye on.