Inverter noise level?

SPASPA Registered Users Posts: 5 ✭✭

Greetings to all,

 First, let me thank you for the great posts and comments on this forum. That helps solar newbies like me a lot.

 I will be installing an off-grid solar system in Haiti and need some advice on the inverter I selected: Magnum MSPAE4024. The room housing the electronics (Combiner, Charge controller, Inverter, etc..) is small and shares a brick wall with a bedroom. Obviously I was concerned about equipment noise so I recently contacted Magnum about the noise level of the MSPAE4024 thinking that the fan noise could be a nuisance for the folks in the bedroom. To my surprise the Magnum tech that emailed me back said that the “humming” of the large transformer was the source of complaints not the fans! I then asked for a dB sound level of this “humming” so I could simulate and see if this will be a problem for people sleeping in the said bedroom. Magnum replied that they had no data for the sound level.  Unfortunately (or fortunately?) that created some doubt in my mind and I started wondering about my choice, hence this post today.

 Would any of you have an idea if the humming sound of the large transformer of any of the 4000W Magnum inverter (at its loudest) is loud enough to be a nuisance for people in an adjacent room? Could anyone with such a magnum post a recording of that sound (using a smartphone up close to the inverter should be good enough)? This would be very much appreciated. BY the way constructive comments are welcome.

 I have combed the NAWS forums and most of the “expert” Youtube channels for this info but could not find anything useful.

 I also did a lot of research before selecting the MSPAE4024/4448 (yes, I might use the 48V) and my top three were: Magnum, Outback and Schneider. After reading much about the three on various forums it seems as if the MS was the least problematic and is sold locally in Haiti so getting access to some level of support from the dealer should be possible.

 Here are the site parameters just for the record:

1.      Location: Haiti
2.      Offgrid cottage
3.      120V/60Hz – might need 240V hence the “PAE” version of the Magnum 4024
4.      5h-8h of good sun light per day (Haiti)
5.      Max AC loads: 2000W (all loads on)
6.      Daytime energy needs: 1.5kWh
7.      Night time energy needs: 5.5kWh
8.      Only need 1 day of operation @ 7kWh. On cloudy days usage will be cut back to strict minimum ( about 3kWh)
9.      8x SW-270W Solarworld Panels (2160W)
10.   Classic 150
11.   MSPAE4024/4448
12.   4x Rolls S550 (considering going to 8), 50% discharge.

 (I ran the above numbers against (BB.) Bill’s excellent rule of thumb calculations in NAWS post #: 351264 and I should be in the bulk. I think my battery capacity is a little low for 7kWh that is why I might go to 8x S550 @ 48V and will add one more panel to have 3 strings of 3).

 Thanks in advance!




  • mike95490mike95490 Solar Expert Posts: 8,073 ✭✭✭✭✭
    With my Schneider, the larger the load, the more hum there is.   When a big motor kicks on, there is a loud buzz for half a second.  I'd put a plywood panel on the block wall to help act as a deadner/isolator.  Otherwise, the wall may become a sounding board.
    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

    gen: ,

  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Welcome to the forum,
    yes, you will need the 8 batteries.  When those batteries are putting out high currents at night, you can expect some voltage sag... you may have to set your LVD (low battery disconnect) lower than you might like.

    About the humming noise.  It's real and I don't think it makes much difference which brand you buy.  It probably can be heard through a brick wall.   Charge controllers are also known for keeping folks awake at night with their relays clicking.  

    When you lie awake in bed at night, ask not for whom the inverter hums, it hums for thee.

    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • littleharbor2littleharbor2 Solar Expert Posts: 1,135 ✭✭✭✭
    vtmaps said:
       When you lie awake in bed at night, ask not for whom the inverter hums, it hums for thee.

    Love this answer....Ha

    At least a dense brick wall will be quieter than a simple wood framed wall. May not be an issue at all. Have you tried a similar type sound test ?

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 700 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • BB.BB. Super Moderators, Administrators Posts: 28,320 admin
    edited July 2016 #5
    You have two ways for sound to conduct... One is through the air--And standard things will reduce that noise dramatically. Brick wall, extra sheet rock (or cement board) between inverter and brick wall (the "studs" supporting the second membrane should only be anchored at top and bottom of wall--Direct mounting of studs to brick behind gives better "conducted" noise transfer.

    And that takes us to conducted noise. If you can mount the inverter "not" to the brick wall (or some sort of rubber isolation) should help too.

    If you have a "smart phone"--There are some pretty nice Spectrum Analyzers for free:

    I use this one (works well, simple, and free):

    I find a spectrum analyzer to be really helpful... And it is nice when somebody complains about high frequency noises that I can no longer hear (apparently--getting old is not fun).

    The transformer noise is typically 2x line frequency (120 Hz in North America)... Seems to be more irritating that fans (which are "white" noise--a wide frequency range of random noise). But some devices do have very loud fans (like some MPPT charge controllers)--But usually most people are in bed after the sun is down--So, at least, you have quiet nights.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 28,320 admin
    PS: I think Seb is talking about this thread for system sizing (we do not have an easy way to find post numbers):

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 28,320 admin

    I would also suggest you look up the solar data for your location. Folks tend to overestimate how much "noon time equavalent hours"  sun they get:

    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 72° angle from vertical:
    (For best year-round performance)
    Jan Feb Mar Apr May Jun
    Jul Aug Sep Oct Nov Dec
    Still good sun--But marine layer/haze/morning-evening clouds can reduce sun significantly.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ramlouiramloui Solar Expert Posts: 103 ✭✭
    edited July 2016 #8

    I have the same MS4024PAE inverter at my cabin and I am very happy with it. As for noise, it is more of an electronic buzz. If your inverter is mounted in a different room than where people are, then I don't think the humming will ever be an issue except at night when everything is quiet. The brick wall will do a very good job of shielding this noise. If you can add a door to the room, then even better.

    That said, at night, when your loads are at a minimum, your inverter may go in search mode to minimize its power consumption. At that time, the buzzing stops but the inverter starts tick, tick, ticking as it waits for a demand. To resolve that, you could turn off that feature or shut the inverter off at night.

    Anyway, as others have said, it is not an issue unique to Magnum or to inverters in general. All electronics will have some buzzing. And we are all affected (annoyed) differently by that.

    As for me, I was made aware of the potential buzzing when I was designing my off-grid system and I decided to locate all of the electronics in the shed. I certainly don't regret that because I can enjoy the very calm and quiet surroundings right before I fall asleep.

    Good luck!

    Louis R.

    Off-grid cabin in northern Quebec: 6 x 250 W Conergy panels, FM80, 4 x 6V CR430 in series (24V nominal), Magnum MS4024-PAE
  • SPASPA Registered Users Posts: 5 ✭✭

    Folks, thanks for all the excellent comments and suggestions above, much appreciated. I will carefully review each and every comment and see how I can make the best use of it.

    Again, I cannot overstate the professionalism and quality of the NAWS forum. :-)

  • SPASPA Registered Users Posts: 5 ✭✭

    Sorry, I wrongly assumed searching by post number was possible. I mentioned above Post: "351264". The full link is below.

  • westbranchwestbranch Solar Expert Posts: 5,123 ✭✭✭✭
    some sound elimination  basics...  I would use acoustic sealant and mount the inverter on a plywood sheet  screwed onto a couple of 2x4 studs that are anchored to a sheet of 2 inch Styrofoam board that is independently mounted to the wall......  glued?

    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • SPASPA Registered Users Posts: 5 ✭✭

    Excellent suggestions. I will take a look at this interesting website.

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