Induction loops. A big error easy to make in solar strings, why haven't I heard about this before?!
- Thread starter Luk88
- Start date
can you explain this a bit?
How much do you know about electricity?
just the basics. just tell me what constitutes as "high power density solar strings"
BarracudaBob
Harvesting free photons from clean fusion
Solar panels are like big capacitors with diodes so you would think they would be more receptive to RF/EM receiver than they are. I can transmit with 1.5 KW on HF and have no effect on the Solar panels/MPPT. There must be enough decoupling capacitance to counteract it.
Otherwise you would think it would ack like a big sky loop antenna.
Otherwise you would think it would ack like a big sky loop antenna.
Last edited:
DPC
Canada, Great already
You hurt your what Bob?
My personal opinion is any thing over 100v or 1000w ish. I would only run more volts if I was stuck with a long cable run and needed it.
BarracudaBob
Harvesting free photons from clean fusion
jzampieron
Solar Enthusiast
For folks that like theory...
It's about the EM field flux linking the wires... which is effected by the physical shape of the wire loop.
Lightening (and other weather events -- like solar storms) produces a bunch of EM due to all those charged particles moving around.
en.wikipedia.org
It's not so different from those old AM loop antennas you used to have for the AM radios. They were a particular side/shape to maximize the energy received at a given carrier frequency and BW.
Also... think about it... transformers are loops of wire around an iron core that push/pull energy. More loops, different sizes and shapes all impact transformer performance. We just normally don't have to worry about high-intensity fields on the scale of our yards.
All that said... this is probably not something I'd be optimizing my install for... just buy insurance.
It's about the EM field flux linking the wires... which is effected by the physical shape of the wire loop.
Lightening (and other weather events -- like solar storms) produces a bunch of EM due to all those charged particles moving around.
Flux linkage - Wikipedia
It's not so different from those old AM loop antennas you used to have for the AM radios. They were a particular side/shape to maximize the energy received at a given carrier frequency and BW.
Also... think about it... transformers are loops of wire around an iron core that push/pull energy. More loops, different sizes and shapes all impact transformer performance. We just normally don't have to worry about high-intensity fields on the scale of our yards.
All that said... this is probably not something I'd be optimizing my install for... just buy insurance.
BarracudaBob
Harvesting free photons from clean fusion
A balanced solar DC transmission lines "cancels out" radiation because the electromagnetic fields produced by each of its parallel conductors are essentially equal and opposite, leading to a net cancellation effect, meaning it does not radiate or receive EM fields. Common mode currents are rejected as they don't offer a differential of potential on the transmission conductor.
That works for the wires, but the panels themselves are not laid out that way and will necessarily be a loop in the system.
It isn't clear to me there is a lot of benefit in the balance feed wiring plan. If you have a nearby lightning strike, the common mode voltage will be high, too, and that can cause damage just as much as the differential voltage.
Mike C.
hankcurt
Solar Enthusiast
The suggestion by Luk88 makes sense to me.
I've had a close lightning strike once in my life while a teenager at my parent's house. The neighbor's tree was struck. I was standing by an open window in the kitchen. The window lit up with the lightning flash and at the same time I heard two snaps that sounded like electrical arcs right outside the window, then the thunderous boom. My parents have a ranch house with a french hip roof, so the guttering forms a loop around the roof. I assumed the snaps I heard were arcs on the gutter system. After the thunder, my mom yelled from the living room that she thought the TV had been ruined. I went and looked and saw that the picture was still displayed, but the colors were covered with blotches of purple, green and pink. I told her that we just need to turn it off and on so the degaussing coil would de-magnetize the screen (back in the days of CRTs). She looked at me like I'd just told her the flux capacitor was overcharged in the Delorean, so I power cycled the TV for her and it was back to normal.
So, I was a bit surprised that the emf from the lightning was low enough frequency to magnetize the TV and not destroy it, and I believe it was effectively picked up by a 20 by 40 foot loop of metal gutter.
The other consideration is if this installation would also minimize the radio frequency interference caused by pulsating DC current being drawn by the solar charge converter, which is a much higher frequency. I know in the National Electrical Code, it is required to run home AC wiring for each circuit so that the hot and neutral run the same path to reduce radio interference.
I'm sure there's room for endless debate on how much this wiring method would protect the solar system components, but I can't think of anything it might harm other than my pocket book.
I've had a close lightning strike once in my life while a teenager at my parent's house. The neighbor's tree was struck. I was standing by an open window in the kitchen. The window lit up with the lightning flash and at the same time I heard two snaps that sounded like electrical arcs right outside the window, then the thunderous boom. My parents have a ranch house with a french hip roof, so the guttering forms a loop around the roof. I assumed the snaps I heard were arcs on the gutter system. After the thunder, my mom yelled from the living room that she thought the TV had been ruined. I went and looked and saw that the picture was still displayed, but the colors were covered with blotches of purple, green and pink. I told her that we just need to turn it off and on so the degaussing coil would de-magnetize the screen (back in the days of CRTs). She looked at me like I'd just told her the flux capacitor was overcharged in the Delorean, so I power cycled the TV for her and it was back to normal.
So, I was a bit surprised that the emf from the lightning was low enough frequency to magnetize the TV and not destroy it, and I believe it was effectively picked up by a 20 by 40 foot loop of metal gutter.
The other consideration is if this installation would also minimize the radio frequency interference caused by pulsating DC current being drawn by the solar charge converter, which is a much higher frequency. I know in the National Electrical Code, it is required to run home AC wiring for each circuit so that the hot and neutral run the same path to reduce radio interference.
I'm sure there's room for endless debate on how much this wiring method would protect the solar system components, but I can't think of anything it might harm other than my pocket book.
littleharbor2
Solar Wizard
BarracudaBob
Harvesting free photons from clean fusion
Yes, that is pretty much what I do
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
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To generate common mode, the PV array looks like a stub antenna. Not a loop, no connection to ground from PV +/- at the array. Only other end at inverter, through EMI filters and surge arrestors.
I think that should produce high voltage at array end only.
So I think no surge arrestors at array.
Maybe near field magnetic coupling, not EM wave.
I think most of the energy is DC to 100 kHz if I remember correctly; I looked up the curve once to analyze lightning currents going through two grounding wires (which would go to an air pallet as it carried large ordinance across floor.)
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