Electromagnetic Pulse

OK0KOK

I haven't been able to get a clear-cut answer about an EMP damaging my PV System, reading the countless articles on the Internet, which none discuss PV Systems.. How can I protect my PV System, or is it even possible???
Thank you for your time......






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PhilS

Re: Electromagnetic Pulse

Do you mean EMP from a nearby lightning strike or the kind from a nearby nuclear detonation? Or some other source?

Phil

TnAndy

Re: Electromagnetic Pulse

I suspect if they are grid tied and we get much of a burst, all the electronics are toast....the grid being one huge antennae.

Off grid, it would depend on strength of pulse, distance, sheilding you have, etc....very hard to predict......but one of the few 'test cases' was the atmoshperic texplosion in 1962:

”in July 1962 the [American] Starfish Prime test [1.4 Mt, 400 km.altitude] damaged electronics in Honolulu and New Zealand (approximately 1,300 kilometers away), fused 300 street lights on Oahu (Hawaii), set off about 100 burglar alarms, and caused the failure of a microwave repeating station on Kauai, which cut off the sturdy telephone system from the other Hawaiian islands…”

I would assume without a spare inverter and charge controller at a minimum, protected in some kind of sheilded area, you'd be as out of power as the rest of your area.

niel

Re: Electromagnetic Pulse

do search this forum as we have had a number of discussions on that subject. there are measures you can do to help minimize or stop damage.

OK0KOK

Re: Electromagnetic Pulse

PhilS wrote: »

Do you mean EMP from a nearby lightning strike or the kind from a nearby nuclear detonation? Or some other source?

Phil

nearby nuclear detonation

OK0KOK

Re: Electromagnetic Pulse

niel wrote: »

do search this forum as we have had a number of discussions on that subject. there are measures you can do to help minimize or stop damage.

Oh-my....
I did a EMP search, but I must have missed something....
Thanks Niel; I'll search again...........


.

niel

Re: Electromagnetic Pulse

some of it may be under the subject of grounds as that is key to help alleviate much of the risks. you will see more i believe in the older threads. sorry about the emp search as it didn't show up with that.

cow_rancher

Re: Electromagnetic Pulse

OK0KOK wrote: »

nearby nuclear detonation

OK, having worked EMP hardening for the Army, I can answer this one. Solar cells are semiconductor, if it is energized and tied to the grid it will probably be toast. If in storage for use after the balloon goes up, and set up after pulse, then yes that would probably be ok. I don't think there is anyway to shield them before the burst since they need to be exposed to the sun, so a nonferrous shield would not work as that is what is normally used to protect communications equipment.


Rancher

niel

Re: Electromagnetic Pulse

cw,
you are right on that as a direct lightning strike or nuclear emp would do that to the pvs. most of the rest of the times it is a lightning emp that does damages and as was stated in many of the past threads, there is no guarantee to not get damages. every step taken can help increase the chances of equipment survival.

OK0KOK

Re: Electromagnetic Pulse

cow_rancher wrote: »

OK, having worked EMP hardening for the Army, I can answer this one. Solar cells are semiconductor, if it is energized and tied to the grid it will probably be toast. If in storage for use after the balloon goes up, and set up after pulse, then yes that would probably be ok. I don't think there is anyway to shield them before the burst since they need to be exposed to the sun, so a nonferrous shield would not work as that is what is normally used to protect communications equipment.


Rancher

Thank you for taking the time to answer my Question.....
I'll store two 200 watt Sun PV's in the basement....




.:D

niel

Re: Electromagnetic Pulse

in a nuclear emp event that may not be enough to stop damages, but you probably wouldn't be around anyway to use it.

TnAndy

Re: Electromagnetic Pulse

niel wrote: »

in a nuclear emp event that may not be enough to stop damages, but you probably wouldn't be around anyway to use it.

Don't know if that would shield enough either, but as to the event, a nuclear EMP attack could simply be just that.....an EMP attack with no ground damage. My understanding is 3 or 4 high altitude bursts would take out most of the electrical infrastructure of the country and knock us back to the 19th century, technology wise.

One Second After

AntronX

Re: Electromagnetic Pulse

EMP induces current across two conductors and between conductor pair and ground. Correct? In that case, can we use Metal-Oxide Varistors like these: http://mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMuQmL5N8IqpX2EE2qA2I0dHjvcXDi7rfig%3d
one between + and - at the solar panel array, and one for each polatiry wire to ground. Install higher voltage rated varistors in similar way at the house AC feed entrance, or even behind every electrical outlet.

mike95490

Re: Electromagnetic Pulse

AntronX wrote: »

EMP induces current across two conductors and between conductor pair and ground. Correct? In that case, can we use Metal-Oxide Varistors like these: http://mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMuQmL5N8IqpX2EE2qA2I0dHjvcXDi7rfig%3d
one between + and - at the solar panel array, and one for each polatiry wire to ground. Install higher voltage rated varistors in similar way at the house AC feed entrance, or even behind every electrical outlet.

NOPE, they don't respond fast enough. EMP is MUCH faster pulse risetime than lighting or ESD. It's very tough to shield against, total fariday shield (I don't know if metal conduit works, or if it has to be steel) helps the most.

AntronX

Re: Electromagnetic Pulse

Hmm, Interesting. I wonder what such pulse does to magnetic storage media such as computer hard drives and magnetic tape. Flash based media is instant toast, right? Maybe burning backup DVD+Rs is not a total waste of time afterall.

Edit: Or better yet, print to 35mm film (I am digital picture person)

BB.

Re: Electromagnetic Pulse

Here is a pretty reasonable looking EMP Primer on Wiki (yea--I know--but Wiki on technical subjects can be pretty good--at least as good as an encyclopedia).

Basically, you will have different frequencies that will travel different distances and such... Small stand-a-lone electronics (flash memory sticks) would require very high frequencies--which do not travel far.

Devices that are attached to utility power can be badly affected by low frequency pluses that energize wires that are miles long--and can focus energy at connection points (i.e., utility power and computer connections).

Off-Grid solar is small(er) so, I would guess, are not going to be as affected by far away sources.

I have done ESD testing (electrostatic discharge; smaller version of EMP) -- basically using a capacitor, high voltage, and a fast high voltage relay to do air and contact testing (simulate human body and equipment static discharges).

This was almost 30 years ago when I started doing it... And from what I have seen:

1. for spark discharges, lower voltage discharges (below ionization voltage of air--700 volts or less--if I recall correctly) generally affected nearby equipment less than a 7,000-15,000 volt discharge. The high edge rate of lower voltage discharges caused higher frequencies which "got into" the computers easier.
2. We also did contact discharges (same test rig, with a high voltage relay to allow current injection with high edge rates that was not affected by ionization voltage issues). Very nasty.
3. As equipment had to meet better EMI regulations and susceptibility tests (pushed originally by European Regulations)--the better the equipment was constructed to limit radio emissions, the better it passed susceptibility testing.
4. Every computer that passed EMI (radiation) testing--always passed the 5 or so susceptibility testing (ESD, conduction from AC "shower of sparks" simulating Florescent Fixture noises, surge testing--electric motor/inductive testing, etc.) with ease (I never had a failure).

So--my two cents worth--following good EMI design techniques (metal boxes, with screws, shielding fingers, shielded cables, Ferrite Blocks, no long wires in loops with no shielding, lots of twisted pairs, etc.) would also do pretty well against outside EMP...

I have seen testing (back in the late 1970's), a simple air gap ESD test would take out computers around the lab in a 100' radius (including the device under test). When I was working in, for example, telephone switch rooms for the phone company--we could not use electronic flash as its EMP would take down the computers. In Alberta Canada, they would have problems with dry air and down coats in winter--guy wearing a down coat would just walk down the isle and crash everything as he passed.

Just a few fixes (improved internal grounding, and such)--and the DUT would pass with flying colors.

When wiring your DC (panels, DC wiring, etc.)--don't make big loops of your + and - cables. Instead, always run them as matched pairs (tied together, same lengths, etc.). And if practical, give them twists (i.e., CAT 5 computer cable has a twist every 1-2 inches).

Now, the interesting thing about off-grid systems--from what I remember our host (WindSun / Admin) answered years ago--it was the AC side of the inverters that usually failed from a lightning strike (classic high energy EMP).

So--if you want things to survive--having a spare inverter may be a good thing to have in your metal spares chest.

-Bill

I should add that putting your wiring in metal conduit (properly bonded to the metal breaker/wiring boxes) is a good thing too.

Solar Guppy has done a fare amount of writing here on his lightning protection/grounding philosophy... And it is quite different from NEC / typical recommendations--but I can see quite a bit to suggest following his methods.

An issue is that "mixing" philosophies in one installation can cause its own problems.

In the end, treat EMP like radio waves (a broad range from low to high frequencies) and avoid issues with making loops of wires (antenna) and bonding gaps (long conduit that gets to within an inch or so of an inverter's wiring box, without a solid metal braid or equivalent connection), and such.

Earth Grounding--I am not so sure that this matters a whole bunch... The bigger help is to make sure that there is a good, heavy gauge (stranded or "flat" braided wire is even better) that attaches to all of your metal equipment cases into one big common electrical "ground" plain.

For safety, you need to dissapate the energy from a direct lightning strike somewhere--so a good (set of) ground rod(s) and a single electrical ground point where everything is connected in a "star pattern" is not a bad thing.

Here is a good thread (with some links) about Lightning and Grounding...

niel

Re: Electromagnetic Pulse

AntronX wrote: »

Hmm, Interesting. I wonder what such pulse does to magnetic storage media such as computer hard drives and magnetic tape. Flash based media is instant toast, right? Maybe burning backup DVD+Rs is not a total waste of time afterall.

Edit: Or better yet, print to 35mm film (I am digital picture person)

if by such an event you mean nuclear emp, then they are toast. even lightning emp can take out such media to varying degrees and not just through the ac side of things even though this is the most common cause of damages. when you think of lightning one usually just thinks a strong flash of light and the sound of rumbling thunder afterwards. this is what we perceive as there's much between those 2 frequency wise and even byond the light that we are seeing. the whole spectrum is there and the strength tapers off as it gets higher in frequency. as bill pointed out it does contain energy in the radio spectrum too and at some of those frequencies it propagates hundreds and thousands of miles just like radio does. any ham here can tell you they have heard thunderstorms thousands of miles away on the hf bands. the higher the frequency, the less likely those big distances will be had just from the atmospheric conditions that propagate it those distances, but with power levels also decreasing as the frequency increases, this too diminishes distances perceived.
a similar thing does happen with nuclear emp, unless it is of the emp design to emphasize the emp destructive abilities, with all frequencies being present (includes not only light, but xrays and gamma rays) and power levels being a gradual decrease as you go up. nuclear emp, however, is so much stronger than lightning emp and so is the destructive capabilities of it. extreme measures need to be taken in order to shield things from such nuclear events. even then there may not be any guarantees. not only would the height a nuke is detonated at extend the distance it covers, but as i pointed out, it will propagate on the lower frequences (this can extend up into the vhf and uhf frequency areas for long distance propagations under the right conditions) and rain destruction from very long distances away with little attenuation in its power levels.
this kind of thing is not easy to defend against and my statement still holds, and even with an emp type device being detonated as was pointed out, that you most likely won't be around to see if your stuff survived.

jacobs

Re: Electromagnetic Pulse

Niel, I like your thinking however there are numerous "experts" that claim it would be very easy for a 3rd world country to launch a nuclear missile from a container ship just off our coast, explode it a few miles up and due to the EMP, we would instantly be living like we did 200 years ago.

niel

Re: Electromagnetic Pulse

i was not arguing against nuclear emp possibilities, but only saying that it is very difficult to defend against such an emp event. it is still a nuclear blast even if it is an emp type and will not be good for life survival even though more may survive with an emp type of detonation. it is an extreme thing to prepare for with no guarantees.

James

Re: Electromagnetic Pulse

You may want to wrap them in aluminum foil and ground the foil wrapping...

stephendv

Re: Electromagnetic Pulse

jacobs wrote: »

Niel, I like your thinking however there are numerous "experts" that claim it would be very easy for a 3rd world country to launch a nuclear missile from a container ship just off our coast, explode it a few miles up and due to the EMP, we would instantly be living like we did 200 years ago.

Humans are wired to be irrational about evaluating risk. We tend to rate risks that are spectacular but infrequent, higher than those that are more mundane but occur more often (and just as deadly). So when deciding what to worry about, it's a good idea to look at real data as opposed to opinion.

Number of people killed in the US by terrrrrirsts since 2000: 1621 (180 people per year)
http://www.start.umd.edu/gtd/search/Results.aspx?expanded=no&casualties_type=&casualties_max=&country=217&ob=GTDID&od=desc&page=1&count=100#results-table

Number of people killed by Coronary heart disease in 1 year: 450 000
http://wiki.answers.com/Q/How_many_americans_have_heart_disease

Number of people killed in road accidents in 1 year ( 1998 ): 41 000
http://www.allcountries.org/uscensus/1035_motor_vehicle_accidents_number_and_deaths.html

If you really do insist on worrying about things, then best to worry about things that are actually likely to kill you

An interesting article on the psychology of risk and the kind of bad risk decisions we tend make: http://www.schneier.com/essay-155.html

niel

Re: Electromagnetic Pulse

carrying stephen's comment 1 step further, lightning emp is something to realistically protect from and nuclear emp is not for storms occur just about everywhere unlike nuclear detonations. in order to protect from nuclear emp it would mean the pvs would not be in use currently, but rather in a secured storage. if you wish to go that far to store pvs on this big if, i'll sell you the bomb shelter to secure them into.

James

Re: Electromagnetic Pulse

From the little info i have located, I would agree that PV's are semiconductor devices with a hugh exposure plane...you may consider wrapping your spare panels in aluminum foil and grounding them. spare electronics is the way to go, but costly.
i keep spare electronic devices wrapped in foil (no exposed openings) and stored in metal cabinets.
Note: no survivalist mentality here, just precaution.
CME's have done some damage in the past. I doubt we will have much warning if one occured, but then, i'm not a scientist.

bmet

Re: Electromagnetic Pulse

except that aluminum foil is not all aluminum, no real benefit other than dust cover. A better 'foil', is that material used for radiant heat barrier in your attic, giving two advantages in the same wrapping.

James wrote: »

From the little info i have located, I would agree that PV's are semiconductor devices with a hugh exposure plane...you may consider wrapping your spare panels in aluminum foil and grounding them. spare electronics is the way to go, but costly.
i keep spare electronic devices wrapped in foil (no exposed openings) and stored in metal cabinets.
Note: no survivalist mentality here, just precaution.
CME's have done some damage in the past. I doubt we will have much warning if one occured, but then, i'm not a scientist.

waynefromnscanada

Re: Electromagnetic Pulse

stephendv wrote: »

Humans are wired to be irrational about evaluating risk. We tend to rate risks that are spectacular but infrequent, higher than those that are more mundane but occur more often (and just as deadly). So when deciding what to worry about, it's a good idea to look at real data as opposed to opinion.
An interesting article on the psychology of risk and the kind of bad risk decisions we tend make: http://www.schneier.com/essay-155.html

So true! I nearly fell off my chair watching the news the other evening. They were discussing the supposed horrible health hazards of having cell phone antennas on apartment buildings, and one lady they interviewed was nearly out of her mind scared about the antennas. They had just told her about the dangers, and she was going on and on about having just stood out on her balcony under the antenna for the last 15 minutes, not knowing the danger - - - while she smoked!
Reality: World Health org. states that world wide, 5 MILLION people die from smoking related causes. Was there even ONE, that died from cell phone antenna exposure?
(Not counting anyone who may have had an antenna fall on them)

Cariboocoot

Re: Electromagnetic Pulse

If the ambient EMF's in our world were really the big danger the media hype makes them out to be, I'd already be dead of cancer sixteen times over. I've been around all kinds of EM fields since I was a small boy, some of them very intense, some of the RF. Not dead yet! My Dad was a radar technician in the Army when radar was new; he used to warm his hands under the magnatron. He's not dead yet either.

Plenty of more serious and immediate health hazards to worry about.

niel

Re: Electromagnetic Pulse

on the subject of radio waves being a danger, they can be. no you aren't dead yet, but i'd be willing to bet some damage did occur as radio waves super heat cells and they can die from it. the cell death or damage is dependent on many factors such as 2 very obvious ones with the strength of the waves and the frequency used. that strength is not just from the power output of the transmitter as being closer to the source and being exposed for longer lengths of time ups the effect.

with radio waves, most of the damage is at the surface of the skin and/or just below it. ask many ham operators about the number of rf burns they have experienced in fiddling around with it. there are very few cases of damage going very far into a person, but it does and did happen. military radar is one example for i know a guy that was near a radar antenna when someone inadvertently turned it on. asside from the superficial burns he got, it scrambled his head enough to disable him, but these are high power using microwave frequencies. low levels from cell towers and phones aren't going to make people suffer great damage, but let's face it many people are goofy to start with so how would one tell?:p her going near the cell tower didn't do damage to her and she is just acting upon her own paranoia brought on by her own ignorance of the subject matter that was perpetuated from an ignorant news media.
the sky is falling. it's just rain stupid.:p:p

Cariboocoot

Re: Electromagnetic Pulse

Exactly so! Microwaves are a lot like fire in that respect; you can warm yourself or burn yourself. Remember MASER's?

That lady with her cigarette on her balcony is in more danger of burning herself while lighting up than from being in line with ambient RF radiation. Probably she'll get skin cancer from standing out in the sun!

Somewhere on the Internet it is almost certain that some shyster is or soon will be selling "RF barrier cream" based on exaggerating this small amount of truth. It probably doesn't even contain titanium oxide!

bmet

Re: Electromagnetic Pulse

BB. wrote: »

When I was working in, for example, telephone switch rooms for the phone company--we could not use electronic flash as its EMP would take down the computers.

When I was in college (early 80's), I worked at a fast food where flash-cameras were forbidden in the restaurant. We were told flashes would ruin the CRT monochrome monitors.

XRinger

Re: Electromagnetic Pulse

OK0KOK wrote: »

Thank you for taking the time to answer my Question.....
I'll store two 200 watt Sun PV's in the basement....
.:D

That seems like a waste of some good PV, unless you live near Iran, NYC, DC or LA.. :roll:

SteveK

Re: Electromagnetic Pulse

According to some highly respected sources 2012 is gonna be a busy solar flare and sun spot year.

Looking forward to the sunspots for Amateur Radio band improvement. Not so much the flares...

I hold a radio in reserve like I do the other things like my signature below.

Wasn't a quarter of Canada knocked out relatively recently from solar storms? It's enough reason for me to be a true believer:roll: