Inverter noise level?

SPA · July 2016

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!

Cheers
Seb

mike95490 · July 2016

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.

vtmaps · July 2016

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.

--vtMaps

littleharbor2 · July 2016

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 ?

BB. · July 2016

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:

https://play.google.com/store/apps/details?id=com.raspw.SpectrumAnalyze

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

https://play.google.com/store/apps/details?id=com.DanielBach.FrequenSee

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.

-Bill

BB. · July 2016

PS: I think Seb is talking about this thread for system sizing (we do not have an easy way to find post numbers):

http://forum.solar-electric.com/discussion/349951/please-haiti-off-grid-system-advice-and-constructive-feedback-needed

-Bill

BB. · July 2016

Seb,

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:
http://solarelectricityhandbook.com/solar-irradiance.html

Port-au-Prince
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
5.58	5.73	5.69	5.69	5.63	6.26
Jul	Aug	Sep	Oct	Nov	Dec
6.26	5.77	5.44	5.22	5.13	5.29

Still good sun--But marine layer/haze/morning-evening clouds can reduce sun significantly.

-Bill

ramloui · July 2016

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.

SPA · July 2016

@all,

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. :-)

Cheers!
Seb

SPA · July 2016

@all,

Sorry, I wrongly assumed searching by post number was possible. I mentioned above Post: "351264". The full link is below.
http://forum.solar-electric.com/discussion/comment/351264#Comment_351264

Thanks

westbranch · July 2016

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?

http://www.noisehelp.com/soundproofing-walls.html

http://www.noisehelp.com/acoustical-caulk.html

SPA · July 2016

@westbranch,

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

Cheers
Seb

Inverter noise level?

Comments

Port-au-Prince
Average Solar Insolation figures

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Inverter noise level?

Comments

Port-au-PrinceAverage Solar Insolation figures

Categories

Port-au-Prince
Average Solar Insolation figures