PV and EMF
I hope the title of this post isn’t provocative, but I would like to ask an earnest question about photovoltaics and magnetic fields. The link below connects to a study of electric and magnetic fields near residential and commercial PV arrays.
It indicates that somewhat elevated magnetic fields are experienced close to PV panels and inverters. The significance of these elevated levels is debatable, but some research studies do point to a correlation between increased childhood leukemia rates and consistent exposure to magnetic fields above 0.3 uT. The Mass. study linked includes measured magnetic fields near 1.0 uT on a residential PV array. It doesn’t indicate if this is a microinverter or central inverter setup.
Tin foil helmets aside, is this something to be concerned about? 0.3 uT is at the high-end of normal background magnetic radiation in typical residences, but is flirting with 1.0 uT a serious concern? Do microinverters produce a less concentrated, and thus less concerning, magnetic field?
Thanks in advance.
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Replies
Jeffrey,
The report you linked to does not raise any concerns. The authors wrote:
"At the residential site, indoor magnetic field levels in the rooms closest to the roof-mounted panels were in the low range of 0.2 to 1.4 mG. There are low-level magnetic fields at locations a few feet from the inverters, in the range of 6 to 10 mG. At a distance of no more than 9 feet from the inverters, these fields dropped back to the background level at this residential site of 0.2 mG. Due to the relatively high background level in the residential site basement where the inverters were housed, the relationship of magnetic field strength to distance from the inverters could not be discerned."
Further on in the report, the authors decided to use the words "very low" rather than "low" to describe these fields: "Magnetic field levels in the rooms on the top floor, nearest the roof-mounted solar panels were in the very low range of 0.2 to 1.4 mG."
For more information on this issue, see EMFs and Human Health.
The inverters at the residential site they discuss are central inverters, not microinverters.
Solar panels themselves are dc and so don't raise any concern.
Inverters and ac wiring on the grid side of the inverter are not very different from other ac power wiring and ac appliances ... and this report is consistent with that idea. If you have decided that the ac power in your house is unacceptably risky, you might consider solar in the same category, but I don't see any indication that it is a new or more concerning risk.
Martin,
Thanks for your reply and link to your previous blog post on EMF. I realize that my original post wasn't as clear as I had intended, and I meant to raise concern about the inverter magnetic fields. The 10 mG (1.0 uT) field is higher than typical background fields (0.3 uT, as referenced in question 19N in the link below). I suppose that as long as the central inverter is 9 feet from typical living space, there really isn't anything to fear.
Charlie,
Thanks for clarifying that it was a central inverter. I suppose that microinverters would raise the fields experienced close to the actual PV panels and near the subsequent A/C power line that comes from the rooftop array. Given that a field is only generated during the day, I suppose I'm overthinking this.
Thank you both for your feedback.
http://www.mcw.edu/radiationoncology/ourdepartment/radiationbiology/Power-Lines-and-Cancer-FAQs.htm
Only the industrial scale inverters were putting out any significant EMF, and even those were well within established safety limits.
The home scale PV systems registered above background, but only when in close proximity. The power supply of the backscreen lighting of your laptop or LCD TV are putting out more EMF than the 6-10mG they measured a few feet from the inverter. The field strength measured at your pillow from a bedside alarm clock could easily be putting out that much.