Testing for Radio Interference from Solar Inverters

[fresnoboy]

Folks, my home construction project is getting closer to completion, and I am going to have to make some choices in terms of solar inverters. It's a large home, and with a detached garage, I'll have more than 60 panels, and I am a ham radio operator, so getting a system that doesn't destroy the lower HF bands is important to me (esp. since these days those are the only bands that seem to work).

We have a 2 story craftsman home, so the roof has a set of facets that making using a string inverter less appealing from an efficiency POV, not mentioning a few trees that can cause partial shading of some of the panels at various times of the day.

The solar guy I am working with is going to set up a few panels with Enphase iq7 microinveters for me to test with. I have a RTL-SDR with a whip antenna that I can place into close proximity to the inverters, and look for interference in the HF bands, as well as bringing along my ICOM 7300 to test directly. Is there anything else I should try and do to test for interference, or specifically how the inverters should be wired? They will be plugged into to the temporary power at the construction site for the test.

Also, I have heard TERRIBLE things about the Solaredge inverters (specifically the optimizers), but there is a post on one of the Aussie solar sites that claims the P500 optimizers doesn't have the same problems that the older units did. Can anyone validate that experience? The Solaredge system has a lot of advantages but I can't deal with RFI.

I have also heard the maxim equipped Jinko panels are also terrible, but heard they are working on a second version that is supposed to be better.

It's very hard to get authoritative advice because folks who have issues or not have issues rarely document the equipment with specificity - brand alone is not enough!

Does anyone have any recent experience with the interference issue with the newer sets of equipment? Even results with a portable AM radio for interference would be helpful.

I'll definitely pass along what I find so others won't have to go through the same trouble.

Thanks!
Mike

[bcroe]

Similar situation here, radio tower not far from the solar equipment. I was concerned about radio interference
during the day. A quick portable AM radio check at noon revealed very quiet operation. A quality EMI filter
could be seen inside the Fronius IG Plus string inverters.

I read other installations are not so quiet. My thinking is that a simple string inverter reduces the possible
sources of noise to one accessible location, and the mfr can afford to build one pretty good filter/shielding
setup. If there is still excessive noise, additional filtering and shielding could be added at the inverter.

With micro inverters or optimizers the noise sources are spread over many units, which individually must
be much less expensive, implying the filtering may get skimped. The number and locations of that type
equipment makes add on improvements practically impossible. So at least a preliminary test of an
installation should be made before purchase for a noise sensitive location. Bruce Roe K9MQG for 60 years.

[Sunking]

All I can say is good luck because Solar + Ham = Bacon Frying in the HF Skillet. Off Grid is even worse making HF unusable. In CA along the coast where there is a lot of solar, commercial AM broadcast is no more heard. An STL antenna might help, but open wire or verticals may not be usable. Hope you like VHF/UHF.

73's

KF5LJW

[sdold]

FWIW my enphase M215 system is about 30 feet from my 80 and 40 meter dipoles and doesn't seem to increase the noise level here, but it is fairly high, I have about S7 noise on both bands day or night, and during the day there is zero change when I pull the breaker to the inverters. If it was a problem I'd just turn them off when operating. Derek, are you ever on 20 meters? I'm thinking of adding a 20 meter dipole here.

Mike, have you tried a ham-specific site like qrz.com? Some of the guys there might have experience with these inverters, maybe even with RFI mitigation. while you're there, look for KF5LJW (Sunking's) three-part grounding article stickies in the antenna forum.

[fresnoboy]

All I can say is good luck because Solar + Ham = Bacon Frying in the HF Skillet. Off Grid is even worse making HF unusable. In CA along the coast where there is a lot of solar, commercial AM broadcast is no more heard. An STL antenna might help, but open wire or verticals may not be usable. Hope you like VHF/UHF.

73's

KF5LJW

Sunking, do you have specific configurations of equipment that you know are toxic from an RFI POV? It would save me the trouble of testing different configurations if I had more specific info.

I really appreciate any help you can provide here about what you have seen work ok, or at least what you know doesn't work,

thx
mike

[fresnoboy]

FWIW my enphase M215 system is about 30 feet from my 80 and 40 meter dipoles, I have about S7 noise on both bands day or night, and during the day there is zero change when I pull the breaker to the inverters. If it was a problem I'd just turn them off when operating. Derek, are you ever on 20 meters? I'm thinking of adding a 20 meter dipole here.

I seen reports that more modern enphase gear doesn't have the problems the old gear has. Any experience with the iq6 or iq7 units?

thx
mike

[Sunking]

Derek, are you ever on 20 meters? I'm thinking of adding a 20 meter dipole here.

Yes sir all the time. Quite a bit working PSK31 ans SSB when the band opens up. I monitor 14.1 Mhz beacon and when I hear W6WX (CA) or 4U1UN (NY) I usually try to get on. For you if you hear YV5B (Venezuela) we can probable work on SSB. 20 M is a pretty easy antenna to make as you are only talking 33 feet or so of wire. On PSK31 I can get through about anywhere in the lower 48 on 40/20.

[Sunking]

Sunking, do you have specific configurations of equipment that you know are toxic from an RFI POV? It would save me the trouble of testing different configurations if I had more specific info.

Off-Grid I can help you with, GT using optimizer or micro Inverters not so much. The real problems I have heard and messed with are Transformerless Inverters.

[BackwoodsEE]

A string inverter can be put inside a Faraday cage. It's not that hard to do with some attention to detail, especially around openings and doors. My entire solar equipment collection--from charge controllers to 48V inverter--is enclosed in a plywood-and-metal equipment shed that provides around 15 dB attenuation at 2.4 GHz and probably much more down in the HF bands. I could do a few things to it to bring that to 20 dB.

Microinverters and optimizers, on the other hand, are out in the open, and you're not going to wrap your entire PV array in chicken wire.

[OldSmokey]

Yes sir all the time. Quite a bit working PSK31 ans SSB when the band opens up. I monitor 14.1 Mhz beacon and when I hear W6WX (CA) or 4U1UN (NY) I usually try to get on. For you if you hear YV5B (Venezuela) we can probable work on SSB. 20 M is a pretty easy antenna to make as you are only talking 33 feet or so of wire. On PSK31 I can get through about anywhere in the lower 48 on 40/20.

although not directly related to the OP's question, this post brought back many memories as a former ham and British ex-pat, I worked with Pete ( G3PLX ) translating his original code to the AMT-1 device at ICS back in the early 80's with 6800 micro's and massive 1 KB static rams..!

[fresnoboy]

Well, I just got back from testing 2 LG panels with iq7 inverters on them. My cheap SDR stick saw noise all over the place, but was not correlated with the panels being on or not. This may be due to an AM broadcast station being nearby overloading the front end, as my ICOM 7300 had no issues with noise in the AM band and could hear weak AM stations from a couple hundred miles away (this was at 11 AM local time).

I did see a fair amount of noise higher up (in the 7-15 MHz area), but again, not correlated to the iq7's being turned on.

My solar guy has installed a ground mounted 100+ panel solaredge array at a site about 30 mins drive away, and they were using P505 optimizers (all brand new), so I may see what the RFI from that looks like as well.

Comments? What else should I be looking at?

thanks!
Mike

[Sunking]

Mike it is going to be a crap shoot. Transformerless designs tend to be noisy. You are just going to have to take your chances. Off grid systems tend to be very noisy because of the Controllers. In off-grid there are only 3 manufactures I know of that are reasonable quite but still require ferrite coils on the battery and panel leads. It just the nature of SMPS and lack of filtering built into the equipment.

[fresnoboy]

Mike it is going to be a crap shoot. Transformerless designs tend to be noisy. You are just going to have to take your chances. Off grid systems tend to be very noisy because of the Controllers. In off-grid there are only 3 manufactures I know of that are reasonable quite but still require ferrite coils on the battery and panel leads. It just the nature of SMPS and lack of filtering built into the equipment.

Thanks. I'm not offgrid at all - it's suburban here. It's the nature of the roof on a craftsman home that necessitates using an optimizer or microinverter instead of a string inverter.

I will have the solar feeds on their own circuits on the panel, and will put filters on that. But I am more worried about noise coming from the roof mounted components. There was a WST story on issues with Solaredge, but they gave no details on which optimizers were being used.

thx
mike

[Sunking]

All I can say is you get what you get. Today's FCC is not yesterdays FCC, and today's technology is not yesterdays technology. Back in the day Hams had some clout and were trend setters, not today are are now antiquated and archaic technology. The days of HF are gone and replaced with UHF and microwave. Bandwidth is the name of the game and UHF and microwave are not bothered much by RFI. HF DX has been replaced with satellite and over 100,000 cell towers in the USA alone. FCC is taking away bandwidth and sold to the highest bidder. Basically about all bandwidth from 450 Mhz and up are for sale to ATT and Verzon with the exceptions of some chunks here and there for DOD. If you live away from the cities HF can be good.

When I started I worked for a utility and at the time most all utilities had departments that specialized in RFI. All that is gone, HF is no longer a priority in FCC eyes. Sad but that is the way it is.