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My HF Radio is Interfering with my Solar System

Discussion in 'RFinderPi - Open Source radio interface based on R' started by KF6IRK, Oct 8, 2021.

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  1. KF6IRK

    KF6IRK Ham Member QRZ Page

    Note: I'm not sure if this is the correct forum, so the admin(s) can move it if need be.

    Most of the articles I read regarding Amateur radio and solar systems discuss interference on the radio equipment emanating from the solar system. Unfortunately, I have not found any articles that discuss interference from the radio equipment to the solar system. I'm hoping to hear back from others who have had the similar experiences and hopefully receive some sound recommendations to cure the matter.

    The Station Equipment:

    My HF rig (ICOM IC-7300) is causing interference to my solar system. Sometimes, even transmitting with only 5-watts causes the solar system's inverter (Trace/Xantrax 4048) to shut down and it stops powering the 120-volt output to the connected loads. I typically use the HF radio in the nighttime hours on 75m and 40m, and the problem seems to be worse when the air is moist (fog, coastal marine layer, etc.), however, the problem doesn't appear to be an issue during daylight hours, even when transmitting with 500-watts with an Elecraft KPA500 amplifier through an LDG AT-1000 auto tuner on either band.

    The Property:

    My lot is 40' wide (north to south) x 140' long (east to west). The antenna is a G5RV, strung east to west along the north property line. The center mast is located on a fence post near the rear of my house, approximately 25' above ground level, with the ends approximately 14~15 ' above ground. Each end has approximately 10' of Dacron rope from the insulators to the tie-off points. The east leg of the antenna travels above the roof-line of my house, and ties off to a tree branch in the front yard. The west leg travels across my back yard and ends approximately 15' away from where my charge controller and inverter are located in the detached garage. There is a 1:1 current balun between the coax and ladder-line situated on the roof of the house.

    The Solar System:

    I installed the 4kW solar system back in 2001. The system consists of 40 PV panels mounted on racks on the south side of a single story gable roof. The wiring from the PV array terminates to 10 individually fused circuits in a combiner box located near the rear of my house. The output from the combiner box runs 20" underground in gray PVC conduit approximately 40 linear feet away (to the west) to a closet in my detached garage, where the charge controller, battery bank and the inverter is installed. The inverter is also connected to the electrical grid that's across the alley behind my garage.

    The system's battery bank keeps the inverter alive should the electrical grid ever go down, and it has previously done so. The longest we've endured a grid outage was due to an automobile accident taking out wiring and several transformers in the neighborhood ... it took several days for the utility company to complete the repairs. I thought the battery bank could have possibly been the problem, but I've powered down the solar system and tested the batteries under load. I started readings at 54.6 vDC, and an hour later, the readings were at 54.2 vDC, so the batteries don't seem to be the culprit (?)

    I've included an aerial image of the property with the radio and solar components' locations indicated.

    Curious as to why the interference doesn't manifest itself during the daytime hours, but only at night? Again, and suggestions/recommendations appreciated.

    ... Mark

    Cota Solar & Antenna Routing.jpeg
    Last edited: Oct 8, 2021
  2. KP4SX

    KP4SX Premium Subscriber QRZ Page

    What solar controller are you using?
  3. KF6IRK

    KF6IRK Ham Member QRZ Page

    Two (2) Trace/Xantrex C-40 PWM controllers. The controllers aren't passing voltage or current at night though.
  4. AD5MB

    AD5MB Ham Member QRZ Page

    I would disconnect the combiner output and see if the HF is getting into all that wire. If the inverter works with the PV cables out of circuit I would put a choke on the input to the combiner.
  5. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Found symptoms. disregard.
  6. KF6IRK

    KF6IRK Ham Member QRZ Page

    The controllers electronically disconnect from the PV array at night to keep the battery bank from back feeding the array, but it's possible the underground wiring still could be affected as they runs parallel to the antenna, although they are separated by 15' at the low end and 25' at the apex (center mast) of the antenna.

    There are 10 individual fused input circuits on the combiners and I had installed clamp-on ferrites on the combiner outputs (see image) previously with no positive results. I picked up some additional clamp-on ferrites from Commline yesterday and installed them on the PV input and battery connections at the controllers today ... will see if they help later tonight.

    I'll also flip the circuit breakers upline of the controllers that will physically disconnect the array to see if that has any effect.

    Cota Combiner Boxes.JPG

    Cota Solar Inverters.jpg
  7. KF6IRK

    KF6IRK Ham Member QRZ Page

    Installing additional ferrites on the + & - wiring at the controllers helped somewhat. I was transmitting fine with almost 100-watts without adversely affecting the inverter(s) last night.

    I plan to replace the back-up batteries soon, so when I power the system down, I'll address the AC wiring that runs from the inverters to the AC sub panel in the house.

    The AC wiring runs in an underground conduit, separate from the DC wiring and runs almost directly below the G5RV (as shown on the image below). I'll see if installing some ferrites on both ends of the AC wiring helps even more ... Film at 11

    Cota Solar & Antenna Routing-2.jpeg
  8. WL7PM

    WL7PM Ham Member QRZ Page

    I have a 80/40 meter, crossed dipole inverted V, feedpoint at 36 feet, 40 meter leg ends 15 feet directly above my battery shed, with two parallel stacked Outback Power inverters in continuous operation. No special precautions taken here, and the inverters don't seem to notice 1500 watts output..
    In your case, I suspect your RFI ingress to the inverter is more likely on the AC output leads.
    I'd try some (1 KV rated) .01 uf ceramic disc capacitors line to line, and line to neutral right in the AC breaker box.
    That, or replace the Xantrex inverters.
  9. KF6IRK

    KF6IRK Ham Member QRZ Page

    Last w/e, I purchased some additional snap-on ferrite filters from COMMLINE and installed them on the inputs to my charge controllers ... and that helped a little (if I keep the HF rig at < 100-watts). I also purchased 4 new AGM 100-amp back-up batteries, so when I power the system down to install them, I'll flip the AC breakers and install some more ferrites on the AC cables ...

    Yesterday I installed the new batteries and before I flipped the switches to turn everything back on, I opened up the main inverter's access panel and installed additional mix-31 snap-on ferrites on the AC output circuit wiring that runs underground (almost directly below the G5RV), as well as more on the AC wiring where the U/G run stubs up at the house. Last night, a friend and I chatted on 75m for about an hour, and I'm happy to report that the inverters weren't adversely affected at all - even when running 500+ watts! ... 20 year battle finally won.

    Thanks for all the comments and recommendations ... case closed ;)
    KP4SX likes this.
  10. KC3TEC

    KC3TEC Ham Member QRZ Page

    i got to this a little late but that exactly what i was going to say.
    with the underground conductors parallel to the one leg of the dipole you were inducing a current in the conductors that the inverter did not like so it was shutting down to prevent damage to the system

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