RFI from Solar Inverter (

Lee, KI5ODH, built an off grid solar system for his station. But he is having some trouble. "The inverter is putting out spurious tones through out the ham bands approx. every 20khz. Do you have any suggestions to rectify the problem?"
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[@gregmihran8616]

Thanks for covering RFI from solar-related equipment. I have done over 250 POTA activations always running two 100-watt solar panels under the California sun. I do not use (or need) an inverter in the field but I do use an MPPT charge controller to covert and optimize the ~20VDC from the panels to charge my lithium batteries. While MPPT charge controllers are much better at optimizing the panel output than PWM, they do have their own RFI issue. I resolved this, as well, by putting three Palomar Engineers ferrite beads at the MPPT output in a row, each with the wire wrapped 3x within them. This is equivalent to 3x3x3 or 27 sequential beads (each wrap squares the RF suppression). That's what it took to eliminate RFI from the MPPT controller. I also mounted the controller in an aluminum box (faraday cage) which greatly helped. :) 73 KJ6ER, Silicon Valley

[@robertmeyer4744]

I got Morningstar MPPT and Victron MPPT controllers. fixed with ferrite. type 43 with several turns of heavy wire. 73's

[@forgottenamericana]

You da man Dave!! I am having the same problem with RFI in my 5th wheel RV that has an inverter and solar.... Just picked up ferrite beads today and will be putting them on soon... THANK YOU!

[@jimmoss9584]

What size and type toroid's would be best? There are hundreds of types. This is also a problem with inverter generators. I don't think that just a couple of toroid's will do much. You are going to use networks in a Low Pass configuration to take care of this noise.

[@robertmeyer4744]

That works. I have a off grid solar/wind home . also i found that LF inverters not as bad RFI noise. my big RFI maker was my MPPT charge controller. ferrite cut it down a bunch . I also put ferrite on my PV panels and win gen . I got ferrite all over my system. was a big help. what I was doing was eather waite to night or switch off solar when wanted to work HF. now my LG washer is quite bad RFI. ferrite did nothing. we don't wash cloths 24/7 so just time washing clothes when not on HF. that was my fix. 73's

[@sincerelyyours7538]

Thanks Dave. The system you described converts the square wave output from the switching circuitry into a modified sinewave which looks more like a series of stepping stools than a sinewave. They are very harmonically rich and so produce a lot of RFI. Some higher-end inverters put out a "pure" sinewave and often produce as little as 3% THD or less depending on how much current you extract from them. They are naturally more expensive. I wonder, how well do these pure sinewave inverters work regarding RFI, and can they, too, be filtered with ferrites?

[@LaneLarson]

Great video as always. Thanks for the clear and in depth explanation!

[@rogerp5816]

You didn't mention what mix should be used for this type of problem. I would think mix 31 would be a good starting point for the ferrites.

[@haroldskinner1783]

Thanks Dave, that was a very informative

[@donalddodson7365]

Very helpful, as always! Brings back great memories of my 8th grade science teacher, Mr. Frederickson. Thank you. 73 KI6GZK

[@dayleedwards3521]

Sadly, RFI filtering is the first casualty of the "bean counters" when saving costs and maximising profits...... its the stuff that goes unnoticed by most consumers. In the DC to AC mains inverter, the squarewave DC/DC primary converter is the cause, usually operating at several hundred kilohertz. Low frequency inverters are available, these operate similarly but use a normal iron cored transformer running at 50 to 100 Hz, therefore the harmonics are very much less. Unfortunately, solar controllers, either MPPT or PWM use high frequency squarewaves too, these are very difficult to supress, the usually long cabling from the PV panels act as an aerial to effectively transmit the harmonics a great distance. Unfortunately, it takes rather more than just clipping on a few ferrite cores to supress these birdies.

[@sunnies336]

what do you suggest?

[@donalddodson7365]

Thanks!

[@darinhitchings7104]

Good video. I once built myself a power supply from the book Forest E Mims III called Getting Started in Electronics... when I was 11. I'm actually building myself another one now... 33 years later. But the material from that book would have answered this question. In particular for the voltage regulator circuit. Also, google circuits that can be used to transform square waves into sine waves... they show several filtering stages that could be used to add low pass filters onto the output of the solar inverter...

[@richardnalisnick462]

The MPPT charge control are and the noisy ones. 73 W3AMT

[@christophermusgrave3105]

Super Informative Dave. Thank you! It would be. Great to know if there are inverters for on/off Grid inverters re high/low freq.ones better or worse than others.

[@godarklight]

I see exactly this problem as well whenever the induction stove is on as well, but I can just wait for that one ha

[@andrewwhittaker6622]

I've been dealing with the same issues with my off grid and SWL setup Tried beads and built line filters with limited success One thing I would add which I would have thought wouldn't matter I used the same earth for my radio's as my panels. Easy it's not far from my shack🤔 But trying a last effort i put another earth in several metres away which cut the noise to a more tolerable level Also my inverters in an enclosed metal shed and even leaving the door open increases QRM I still have noise but i can get good copies on DX stations in the US and European stations from my place in NSW on my old R100 and inverted V Cheers

[@stevegordon2869]

I have 50 acre fields of solar panels in that the power company has put in radio is about done for. Here in Sandoval Illinois. 73s N9wzl

[@116Penfro]

Dave, there are two conduits coming into my inverter. Would it work if I just put a ferrite around the conduit if I can find one big enough? There is no battery in my system. I imagine one conduit comes from the solar panels and the other is going to the grid/house.

[@notsogreat123]

All inverters have rfi. It's just the nature of the beast. Vert difficult to filter all that out.

[@ralph9987]

Interesting video Dave. I have a solar charger on the shack to charge my 12v battery which powers my ftdz3000. the charge controller (no mains connect) creates RFI despite installed ferrites. what other options do I have? thanks

[@g-whiz286]

Turn off the charge controller and operate from your 12v battery when you are operating. Turn the charge controller back on to charge the battery when you leave the shack or are not operating.

[@ralph9987]

@@g-whiz286 I was hoping to hear options that will allow me to continue to operate the charger. whatcha got?

[@g-whiz286]

@@ralph9987 I don't. I just turn mine off. I even have to turn off the shack laptop because that thing is radio free Moscow even when running on battery.

[@josephrogers5337]

My plan would be for an off-grid situration. Have a shed, charge the batteries to large 12v bank. Power the who shack off of 12 volsts, and no wall-warts, and even 12 v. incadesent lighting. No Ac al all and some distant from any ac. Should be altra rfi quite. great for weak signal reception.

[@g-whiz286]

You have the right idea, but I really need a computer in the shack. I have found that even a small laptop running on battery is a terrible radiator of all kinds of RFI. If I turn that off, the noise floor quiets down quite a bit.

[@josephrogers5337]

A square wave is the sum of all the odd harmonics.

[@jackolsen8677]

I have an outback fm80 solar charge controller feeding my repeater battery bank and it makes 80 and 40 m unusable no inverter is used in this system,so be careful when you design a system with amateur radio in mind

[@shipk2323]

You have not suggested any new ideas about reducing RFI. Grounding and ferrite torroids not solve rfi.

[@glenmartin2437]

Thank you. N0QFT