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Thread: Making a PV system survivable in EMP/CME conditions?

  1. #1
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    Default Making a PV system survivable in EMP/CME conditions?

    Ok, I figured to broach this subject since there's been renewed discussion in the media about how much at risk we are from CME (coronal mass ejection) and EMP (electromagnetic pulse) threats to the power system and all associated electronics. In my research on these, the two things that came up was that the solar panels, batteries, and other non-electronic devices are impervious to these events. They may throw a hissy fit, but otherwise they'll come through them just fine.

    However, the charge controllers, blocking diodes, and inverters, as well as monitors, battery switchers or other electronically based devices would bite the dust. Equivalent mechanical devices would not be affected. (ie, switch based mechanical charge controllers and the like) So I'm curious what you guys think about these proposed threats. Is a PV system actually vulnerable to such threats, and if so, which parts and what's the best way to protect them? And if they can't be protected, what's the best way to protect the spares?

    Now I'm not trying to cause any wild paranoia here. I'm just practicing good CYOA, because I know that even though these are worst case scenarios, something as mundane as normal wear and tear, or even lightning could produce the same damaging effects. Hence why I'm asking so that I'm properly prepared. :) Sorry, it's just the boyscout in me trying to ensure that all my bases are covered.

  2. #2
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    Default Re: Making a PV system survivable in EMP/CME conditions?

    We have a few threads here about CME and EMP:

    Solar Flares/Sun spots

    EMP
    EMP
    HAM with some EMP

    From my post in the Ham Radio thread:

    This guy wrote something that I pretty much agree with (with my limited education):
    To answer the specific question of the OP, it depends upon the application. Military electronic hardware, save for acceptable commercial-off-the-shelf (COTS) components, area built to specific interface standards like MIL-STD-464 (Electromagnetic Effects Requirements for Systems), MIL-STD-461 (Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment), and MIL-STD-2169 (Classified) (High Altitude Electromagnetic Pulse Environment). The latter is probably most pertinent to the question, and for obvious reasons unavailable to the public at large. However, the ugly truth about high altitude EMP is that no amount of shielding, save being buried deep under hundreds of feet of rock or dirt, is really adequate to protect sensitive microelectronics. By their nature, the electronics are delicate and sensitive to small levels of excess voltage, and it is nearly impossible to make a practicable sensor, communication system, or avionics control that has to interface with the outside world and yet is adequately isolated against large pulses.

    High altitude EMP (HEMP) devices produce three distinct regimes of pulse, referred to as E1, E2, and E3. Microelectronics are most sensitive to E1, which is due to interaction of x-ray and gamma ray radiation with the rarified upper atmosphere and the geomagnetic field resulting an a nearly coherent, widely distributed pulse, sort of like a very large free electron maser. In more dense atmosphere where the the rays are rapidly absorbed and don't have much length to deflect, this pulse is serious attenuated, and the amount of damage done but the physical effects of the blast (shock and thermal wave) would likely make E1 effects moot. E2 is more like static electricity, and can typically be shielded by using a protected ground or faraday cage type shielding. E3 is energy that is stored in the Earth's magnetic field (similar to that which comes from coronal discharges and solar flares) and will cause longer term disruption and very high voltage spikes in large arrays like power grids; again, not much of a threat to microelectronics.
    So, from my point of view, the solar flares produced relatively low frequency changes in magnetic fields... Probably would take structures on the size of miles or 10's of miles to capture the energy (1/4 wave length or larger?).

    Here is a wiki entry for geomagnetic storms:

    Electric grid When magnetic fields move about in the vicinity of a conductor such as a wire, a geomagnetically induced current is produced in the conductor. This happens on a grand scale during geomagnetic storms (the same mechanism also influences telephone and telegraph lines, see above) on all long transmission lines. Power companies which operate long transmission lines (many kilometers in length) are thus subject to damage by this effect. Notably, this chiefly includes operators in China, North America, and Australia; the European grid consists mainly of shorter transmission cables, which are less vulnerable to damage.[12]

    The (nearly direct) currents induced in these lines from geomagnetic storms are harmful to electrical transmission equipment, especially generators and transformers — induces core saturation, constraining their performance (as well as tripping various safety devices), and causes coils and cores to heat up. This heat can disable or destroy them, even inducing a chain reaction that can blow transformers throughout a system.[13][14][15] This is precisely what happened on March 13, 1989: in Québec, as well as across parts of the northeastern U.S., the electrical supply was cut off to over 6 million people for 9 hours due to a huge geomagnetic storm. Some areas of Sweden were similarly affected.
    According to a study by Metatech corporation[citation needed], a storm with a strength comparative to that of 1921, 130 million people would be left without power and 350 transformers would be broken, with a cost totaling 2 trillion dollars[not specific enough to verify].

    By receiving geomagnetic storm alerts and warnings (e.g. by the Space Weather prediction Center; via Space Weather satellites as SOHO or ACE), power companies can (and often do) minimize damage to power transmission equipment, by momentarily disconnecting transformers or by inducing temporary blackouts. Preventative measures also exist, including digging transmission cables into the soil, placing lightning rods on transmission wires, reducing the operating voltages of transformers, and using cables that are shorter than 10 km[citation needed].
    I do not believe that an off-grid solar array, backup generators, inverter, etc., would be susceptible to a solar flare event.

    For grid tied systems--there may be a risk of damage from surges on power company transmission lines entering the home electrical system (guess on my part).

    An easier way to search our forum... Use Google and the "site:wind-sun.com" tag to limit searches to our forum (or type in the web address of other sites you are interested in). For example:

    • EMP site:wind-sun.com

    Short search terms here work much better with Google than the forum search tool.

    -Bill
    20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

  3. #3
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    Default Re: Making a PV system survivable in EMP/CME conditions?

    Ah, thank you. That explains why I didn't find anything. ^_^ As for the other suggestions, it doesn't look like I have all *THAT* much to worry about. So I guess, baring the extreme example, that my future PV system will be pretty safe from EMP or CME. :)

  4. #4
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    Default Re: Making a PV system survivable in EMP/CME conditions?

    Lightning will probably be your bigger risk... Knock on Wood.

    Quote Originally Posted by BB. View Post
    A couple threads about Lightning:

    Off Grid Grounding Technique?
    Another Question, this time about Lightning

    Note, the above are discussions, not a do A, B, and C--and you will be "safe". There probably is no such thing with lightning. Several different techniques are discussed--and a few of those posters even have experience with lightning.

    And our host's consolidated FAQ page:

    www.windsun.com
    Lightning Protection for PV Systems

    From other past posts here, Windsun (admin/owner of NAWS), he said that most of lighting induced failures he saw were in the Inverters' AC output section.
    -Bill
    20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

  5. #5

    Default Re: Making a PV system survivable in EMP/CME conditions?

    EMP can affect shorter wire length, but the only thing that can produce EMP strong enough to take out an off-grid system is a nuclear air burst. In which case, you have bigger problems.
    Julie in Texas

    greenMonitor(tm) for Morningstar, OutBack and SMA from greenHouse Computers.

  6. #6
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    Default Re: Making a PV system survivable in EMP/CME conditions?

    Quote Originally Posted by tallgirl View Post
    EMP can affect shorter wire length, but the only thing that can produce EMP strong enough to take out an off-grid system is a nuclear air burst. In which case, you have bigger problems.
    i would not go so far as to say that, but it is true that when there's less wire that there is less pickup.
    NIEL

  7. #7

    Default Re: Making a PV system survivable in EMP/CME conditions?

    Quote Originally Posted by BB. View Post
    For grid tied systems--there may be a risk of damage from surges on power company transmission lines entering the home electrical system (guess on my part).

    l
    Tend to agree with the sentiments. Nuclear induced EMP will happen in the event of war. This is designed to knock out power grids electronics etc. The likely hood is slim. Solar storms will tend to knockout the grid networks but solar panels probably will not be directly affected. My concern would be lighting strikes nearby in a tried grid set up. If a storm is approaching isolate the inverter and solar panels from the grid to eliminate any damage.

  8. #8

    Default Re: Making a PV system survivable in EMP/CME conditions?

    Since all these grid-tied systems are designed to NOT WORK in an outage......

    Quote Originally Posted by phred01 View Post
    My concern would be lighting strikes nearby in a tried grid set up. If a storm is approaching isolate the inverter and solar panels from the grid to eliminate any damage.

  9. #9
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    Default Re: Making a PV system survivable in EMP/CME conditions?

    And in a storm, you won't miss much power production anyway.

  10. #10
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    Thumbs up Re: Making a PV system survivable in EMP/CME conditions?

    It is worth noting here that an EMP strike is always survivable by design. In fact, an EMP strike against a nation is not even termed a nuclear strike at all. A detonation hundreds, yes hundreds, of miles above the eatrh is the strategy....not a couple or few. So there really is no rubble so to speak. Just the pile of electronic junk that would result, and a bunch of downed craft.

    Heres one government website that attempts to educate the public on EMP.

    http://www.doh.wa.gov/ehp/rp/factshe...41elecpuls.htm

    So I guess the urgency of preparing for an EMP event would be derived from the circumstances of the nation in question being at war or not.

    Edited: To exclude a certain question.
    Last edited by SteveK; February 28th, 2011 at 6:53 PST.
    6-180W CETC's., Midnite Solar Classic 200, Exeltech XP-1100E, Victron 24V-350W Inv, Energizer 24V 450aH FLA. Honda EU2000i Tri-Fuel. Victron BMV-602. Meanwell PB-1000-24. In Reserve: 2-180W CETC panels, Rogue MPT-3024, Exeltech XP-1100E

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