Protection for computers and other electronics

I am completely off grid. My system is inverted to 120vac with an outback 2000w inverter and is properly grounded and has all the necessary lightning surge protection etc.

For normal use in an off grid solar powered home, it necessary to use surge protector strips for computers etc?

Is there such a thing as a power surge in a properly designed off grid system?

Comments

  • James
    James Solar Expert Posts: 250 ✭✭
    Re: Protection for computers and other electronics

    You have brought up a good question.

    I'll take a stab at it here, and maybe some of the other more experienced contributors can correct me if I'm off base on this one.

    It is my guess that you should still use outlet strips with surge protection feature.
    I'm fairly sure I have read that nearby lightning strikes can induce a surge in inverters and other off-grid components, even your household wiring.

    My feeling is that the extra protection is well worth the cost.
    However, there may be some drawbacks I'm unaware of.

    Does anyone else have further info on this matter?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Protection for computers and other electronics

    I would guess that the possibility of lightening causing problems between grid and off-grid power is very similar...

    If you are worried, you best bet is to make sure you make backups of everything as often as needed to prevent loss work...

    The chances of a hard drive failing or viruses, or even just an oops (erased file, modifications that you can't undo, etc.), are probably more likely than a lightening strike.

    Hard drives last ~2-7 years, and can fail at anytime. A lightening strike that takes out your computer/home electronics is probably a once or twice in a lifetime event (or even less) for most people. Having backups is good practice.

    If you use an USB disk to back up your computer, it probably would not be a bad idea to only connect it (signal and a/c power) when you are actually making backups--if you leave it connected (on or off), the chances of a strike damaging your backup drive are probably higher.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Protection for computers and other electronics

    Inverters (even sine wave inverters) may have some odd output harmonics, that appliances do fine with, but the MOV in most surge strips, will try to adsorb, and fail silently in a few minutes.

    A square wave inverter will toast a surge strip in a few seconds.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Protection for computers and other electronics

    I have not heard that MOV in surge protectors have problems with MSQW and SW inverters... As long as the peak voltage does not exceed that of a normal sine wave (~180 volts peak or so), there should no problems. It has been decades since I had a MSQW inverter on a scope--but the peak of a MSQW should actually be less than than of a normal sine wave in a utility main (Root Mean Square Power would require a sine wave to have a higher peak voltage to have the same RMS as a square wave--~1.41x higher for a sine wave vs a pure square wave with the same RMS voltage--IIRC).

    MOV's are voltage dependent devices and harmonics (which don't add up to more than ~180+ volts peak) should not affect them at all (other than a small capacitive effect with the higher harmonics).

    Have you seen the problem Mike?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Protection for computers and other electronics

    I haven't seen it, but was cautioned about it happening. Now that I think about it, maybe it's diodes that have problems with square waves, much more sustained current than the quick peak of a sine wave.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Protection for computers and other electronics

    Diodes (or any voltage dependent device--even switches) typically have problems with inductive loads...

    When the current is interrupted to an inductor, the field will be begin to collapse in an attempt to keep the current flowing--dramatically increasing the voltage (a few volts can be inductively transformed into several hundred volts very easily) across the switch/transistor/etc...

    That is why a (reversed biased) diode is placed across the coil terminals (in a DC circuit). When the field collapses, the diode shorts out the reverse voltage spike, protecting the switch/transistor from arcing.

    Or, a capacitor can be placed across the contacts (like in an old car ignition system using points in a distributor)--it delays the voltage spike until the points are open far enough to prevent arcing.

    Generally, it would frequency sensitive components (like inductors, capacitors, transformers, motors, and such) which will be most effected by the high frequency components present in a square wave.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
    Re: Protection for computers and other electronics

    i missed this thread, ok let me think about this: my dc circuits have fuses, the whole battery bank has a fuse before it hits the circuit breaker, the inverter has a fast acting fuse, the inverter itself probably has an internal overload. are we imagining lightning is going to strike inside the house past all these safety points?
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Protection for computers and other electronics
    lamplight wrote: »
    i missed this thread, ok let me think about this: my dc circuits have fuses, the whole battery bank has a fuse before it hits the circuit breaker, the inverter has a fast acting fuse, the inverter itself probably has an internal overload. are we imagining lightning is going to strike inside the house past all these safety points?

    Mr. Lighting Bolt (10,000amps, 200,000,000 volts) is not going to be slowed down by a measly 3" gap left by a blown fuse. It's just flown 6,000' or more, and 3" is nothing, heck 30' is nothing.

    You can protect against a near strike, but if hit dead on, plan on calling for replacements from your neighbors phone. Then start cleaning your batteries off the roof of your battery shed.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
    Re: Protection for computers and other electronics

    gotcha ;)

    lengthening my message to 18 characters so i can post
  • System2
    System2 Posts: 6,290 admin
    Re: Protection for computers and other electronics
    mike90045 wrote: »
    Mr. Lighting Bolt (10,000amps, 200,000,000 volts) is not going to be slowed down by a measly 3" gap left by a blown fuse. It's just flown 6,000' or more, and 3" is nothing, heck 30' is nothing.

    You can protect against a near strike, but if hit dead on, plan on calling for replacements from your neighbors phone. Then start cleaning your batteries off the roof of your battery shed.

    Point well made. It always astounds me how so many people I've spoken with seriously believe all they have to do is purchase a power strip and all their lightening problems are over.
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
    Re: Protection for computers and other electronics

    as part of my business I'm a user and seller of ups's, i make a point of using ups's with a connected equipment guarantee or warranty. recent units ive sold or used were a small belkin unit for $40, various APC units, and the most recent sine wave unit from cyberpower also has that kind of insurance included.
  • System2
    System2 Posts: 6,290 admin
    Re: Protection for computers and other electronics

    Speaking of "connected equipment guarantee or warranty", A neighbor of mine a while back had their computer blown out during a lightening storm, beyond repair, and it was connected to a "special" power strip with such a warranty. Guess what - - the power strip company gave them such a hassle and hard time, coming up with every excuse their experience had taught them to come up with not to honor the warranty, that the computer owners finally gave up and purchased a new computer on their own. Now they don't use a power strip. Instead, they pull the plug when they're not using it.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Protection for computers and other electronics

    most power strips only use movs in their protection. cheap ones will have one and better ones with 3. the best ones also have gas discharge if they do this in conjunction with the movs. gas discharge types by themselves are not good enough as more than one surge can go through and the gas tube will blow on the first one. many of those claims of high insured amounts are pr ploys to indicate they have the better strip. to a degree it is probably happening with ups as well, but there are some good ones out there i'm sure that will honor their policy of insuring. it's the good companies that suffer from bad reps of the bad ones long after the bad ones are gone.
    keep in mind that nothing is foolproof, but it is better in most cases than doing nothing.
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
    Re: Protection for computers and other electronics

    what surge suppressor brand was your friends wayne? i highly doubt anyone would have trouble making a claim from a reputable manufacturer like APC.

    saw a cool thing on this old house last night with whole house surge prortectors for only about $250, makes sense if you have an electrician in.
  • System2
    System2 Posts: 6,290 admin
    Re: Protection for computers and other electronics

    I'll try and remember to ask them when I see them again. They will probably remember, as they were upset enough at the time.
  • Bigwooo
    Bigwooo Solar Expert Posts: 62 ✭✭
    Re: Protection for computers and other electronics

    Thanks for all the good information, but I don't think that I received the response I'm looking for, I didn't quite word the question correctly. Let me try again:

    If I'm compleatly off grid using a good quality true signwave inverter. Ignoring lightning, do I need to be worried about power spikes affecting my computer?

    Do I need to use a surge protector strip between my computer and the outlet?

    Thanks.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Protection for computers and other electronics

    Ignoring lightening... No, a MOV protected power strip will be of little use for you or in protecting your equipment. A MOV would probably not trip/protect on any possible over voltage event from a failing inverter.

    About the only time you might still need one is if you have a standard phone line coming into the home (lightening or AC line crosses that get by the protection installed by the phone company).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset