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Off-grid solar and ham radio noise

ericfx1984

ericfx1984

Solar Enthusiast
Joined
Oct 10, 2021
Messages
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So I live off-grid and have a completely off-grid solar setup... 22 kilowatt hours of lithium iron phosphate batteries and several MPPT charge controllers... What I found is the sunnier it gets the more noise I have on all bands

The noise seems to be spaced about every 40 kilohertz

It's kind of a high pitch whining or whirling type sound

I don't notice it when the sun is down and I don't notice it if I shut off my MPPT charge controllers

How can I solve this?
 
You are screwed as long as you have an inverter anywhere near you transciever. Had this problem around 20 years ago when running a 64 ft sailboat in the Carribean. Could not read weak signals but close by strong signals were fine. checked out the Icom over and over again ith all the shipboard electronic shut down but the onboard noise just dials up the AGC and you cannot copy 100 wat signals frommiles away but boats around you can. Finaly figured out the problem when I found that all the shipboard power was 24 volts DC but the radio and some instrumentation was 12 volts and they had a 24 volts to 12 volts converter which was making the noise. I think that the choppers are the culprits and I do not know how you overcome them except by turning them off and operating on your battery while transmitting and receiving. When done turn your inverters back on.
 
First you should find out if the noise interference is at your transceiver or at the antenna. If it's the transceiver, move it farther from your solar gear. If it's the antenna, either move your solar gear or mount the antenna elsewhere.
 
Yeah it could be coming in via the power lines or the antenna.
Also you say you have multiple mppt controllers, I would shut off one at a time and see if there's any particular one that's causing it.
 
If your rig runs off of a battery supply you will have to shut down your inverters and controllers one at a time untill you have nothing but the transciever running and if you still have noise it is external. I still had noise on my 12 volt Icom as it was connected through the power supply to a 24 volt battery so there was nothing I could do about it.
 
You have very limited options. Virtually all MPPTs generate a lot of RFI/EMI. I assume your system is 12v. If that is the case you must bite the bullet and ditch the MPPTs and install (one or several) quality PWM charge controllers (Morningstar TS-45, TS-60 with low Telecom Noise mode {“On-Off” battery charging}). Or use a solid-state relay charge controller (again, “On-Off” battery charging). Because you can’t use MPPT you possibly have to install additional panels (12v).
 
Supposedly, this company's solar charge controllers are very low EMI.

It would require you to make some significant changes as they are designed for use with one controller per ~ 150 - 200 watt panel.

GV-10 – Sunforge LLC

sunforgellc.com sunforgellc.com


You can also replace the aims inverter with one that emits less RF noise and of course do the usual wire shielding / twisted cable tricks.
 
ericfx1984 said:
So I live off-grid and have a completely off-grid solar setup... 22 kilowatt hours of lithium iron phosphate batteries and several MPPT charge controllers... What I found is the sunnier it gets the more noise I have on all bands

The noise seems to be spaced about every 40 kilohertz

It's kind of a high pitch whining or whirling type sound

I don't notice it when the sun is down and I don't notice it if I shut off my MPPT charge controllers

How can I solve this?
Click to expand...
I have used a Renogy MPPT controller and now using a Victron.Neither has made any noise on any band but my HF inverter (Giandel) blankets the whole HF spectrum.I bought a LF inverter ( Sigineer) and run that when on the radio.No noise whatsoever,running everything at 12 volts btw.Others made some good suggestions,hope you at least find what is making the noise.
 
Victron MPPT’s definitely cause noise, see here :


My Schneider LF inverter is far less of a problem than my two Victron MPPT’s.

I’ve used mix 31 and 43 toroids to choke everything I can and remain active from 70cm to 160m.
 
what if you run your ham on a separate battery pack and you isolate as needed
 
GSXR1000 said:
what if you run your ham on a separate battery pack and you isolate as needed
Click to expand...

Forgot to mention, I run the radios on two solar charged LiFePO4 100 Ah batteries. When one is in use the other gets charged.

The amplifier and shack computer run off AC from the Schneider CSW4048. The inverter and MPPT’s are less than 10 feet from the radios.
 
I should clarify... I know the issue is with the SCCs... If I shut them off the noise goes away... If I turn them on one by one the noise gets louder with each unit added
 
ericfx1984 said:
I should clarify... I know the issue is with the SCCs... If I shut them off the noise goes away... If I turn them on one by one the noise gets louder with each unit added
Click to expand...

Easy test them - pick up one of those Genesuns - use it with one of your 200 watt panels and see if the problem goes away.
 
Cant you just build a metal enclosure around the SCC's to act as a faraday cage? This was a concern of mine but haven't noticed any issues over GMRS or wifi with victron components. But my entire RV bays and frame are stainless steel
 
try
JoeHam said:
Forgot to mention, I run the radios on two solar charged LiFePO4 100 Ah batteries. When one is in use the other gets charged.

The amplifier and shack computer run off AC from the Schneider CSW4048. The inverter and MPPT’s are less than 10 feet from the radios.
Click to expand...
a full isolation on a small inverter
 
The Schneider XW-MPPT60-150 is FCC Class B compliant, you don't list what your using now, but that's about as good as it gets for minimizing EMI
 
Solar Guppy said:
The Schneider XW-MPPT60-150 is FCC Class B compliant, you don't list what your using now, but that's about as good as it gets for minimizing EMI
Click to expand...

This is a large part of the reason I went with schneider. From the research I did (back then) it was supposed to be one of the better CC's across the ham bands.

I have a 60/150, and a 80/600, and eventually will be adding 2 more 80/600s.
 
It still is to my knowledge the only FCC Class B charge controller sold. The XW system was and still is best in class.
 
I started to Notice this issue on my Sol-Ark 12K, it really shows up now that the bands have become quieter.
It's no where to the extent that OH8STN is having but the issue is noticeable in the bandscope as faint lines on 80m, 40m, 20m and then goes away at 17m then rears it's head again on 15-10m. I get more of a high pitched RFI tone and I can eliminated with the Notch filter on the Fine setting but it does distort any station that is on that freq.

It is almost undetectable at 5-10A of charging current but once I go past that it goes up. At the full 40A or 9KW of PV output it is really noticeable on 20m.
I am not personally using 40m or 80m in the day so that does not matter to me, but 20M and above is annoying.

Killing PV power gets rid of it instantly.
Basically I have all the same issues as OH8STN, at a much reduced level.

I honestly did not notice this problem until this summer when the bands got better and the QRN was low.

Great video, I was about to buy some Ferrites, but now I think I will try to approach the problem from a different angle.
 
Last edited:
I have this issue too. MP2424 and very noticeable on 20m and up making it unusable. 40 and 75m no problems. Moving the antenna further away helps obviously but I don't have enough property. Much of it is coming out the AC lines from the inverter because disconnecting the PV doesn't have noticeable reduction. Large ferrites may help but I don't run it while on the ham radio but with electricity more than doubling in cost this year, I might start using it more for lower power loads.
 
From what I am learning the noise is created by the MPPT's oscillator used in the circuitry to sweep the panels for the best power point. It is typically a frequency in the 15 -30Khz region.
I did a rough check on the Sol-Ark and it is at about 23Khz. This weekend I will check it out with a spectrum Analyzer.

Any Ferrite's that are added need to be ones tuned for the Frequency that is causing the Interference or at least very close to it.
 
robby said:
From what I am learning the noise is created by the MPPT's oscillator used in the circuitry to sweep the panels for the best power point.
Click to expand...

Most single stage mppt charge controllers are simple buck switchers. The radiated emissions is switching frequency of this converter, which in most units is digitally controlled with a DSP. The emissions come from the FET source pin(s) begin switched on/off via pwm of the DSP and requires significant filters to meet FCC regulations.

Sadly, at least when I was active designing, almost no manufacture bothered with the FCC requirements.
 
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