Off-grid solar and ham radio noise

[robby]

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.

 

[mactech]

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.

 

[HarryN]

My understanding is that the Genesun's are the lowest RF noise controller on the market but could be wrong.

 

[robby]

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.

 

[Solar Guppy]

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.

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.

 

[JWLV]

Come to think of it, I don't remember seeing any FCC logos on any of my solar gear. I suppose most of them didn't bother with it.

73s

 

[Prince Of Darkness]

For electronic devices which are NOT connected to the AC power mains, the Emissions tests begin at 30.0 mHz. So, stand-alone MPPT SCCs fall into this category.

FCC Part 15, Class B Emissions tests for these SCCs are only for Radiated Emissions, not Line Conducted emissions. Generally, most of thesee SCCs are usually containd in fairly tight metal enclosures, which greatly reduces Radiated emissions.

Line Conducted emisssions test (for those devices which ARE connected to the mains) start at around 100 kHz, and stop at 30 mHz. This encompasses the LF, MF, and HF bands. This range happens to be the frequency range where, for MPPT SCCs, almost all of the significant emissions are located.

Line Conducted emissions test use a specific AC line interface (the LISN), and for FCC Class B, I know of no way, that is FCC-defined, to measure conducted emissions, below 30mHz.

So. for me, FCC Class B compliance of stand-alone MPPT SCCs, is of little use.

There is a provision in Part 15, that un-intentional Radiators " shall not create harmful interference" (or similar), but this seems to be of little use ... just at the horrible RFI, coming from DC Optimizers !!

IMO, 73, Luke

 

[jpimlott]

One option to try is to put 2 caps (high voltage) in series with the middle going to ground.
One these on the PV coming and the other on the battery cable. I have had some success with this but perfect
It is cheap to try. A fellow ham here

 

[JoeHam]

My understanding is that the Genesun's are the lowest RF noise controller on the market but could be wrong.

True but the sticking point is that their models top out at 10 Amp output.

 

[HarryN]

True but the sticking point is that their models top out at 10 Amp output.

Yes - that is a problem. I have used some of their other controllers and improved the thermals by mounting them to a piece of heavy aluminum angle and some thermal paste.

The OP has a couple of 200 watt panels and could use that as a test.

I should send an email to their sales manager and ask him to come up with some higher power units.