Radio Noise from PV System

[niel]

try adding even more capacitance and use the ferrites too and see what happens. come to think of it, were the ferrites still inline when you added the caps or not as you didn't say? why did you not just go to the 40 meter band and see what your caps did as it is a matter of just going up the dial?

[W0SD]

Ferrite Cores

I re-read all the post several times and will do so again. Questions were asked about ferrite. FYI I have tried 4 clip on ferrite cords on each PV input wire for a total of eight that just fit over my wire. They do absolutely nothng!!! I have tried them all on the battery wires and absolutely nothing and I have used them on both the PV input and the battery leads. I have moved them from as close as possible to the controller to farther away. The clip ones were gotten from Northern Sun and WInd and should be the correct material.

Ed W0SD.

[niel]

is there enough room inside of the ferrites to loop more turns through it? if not then leave the ferrites there and just concentrate on adding more capacitance as that has shown a result.

[W0SD]

I should of went to 40 meters, dumb mistake on my part, but I was fixated on getting a valid test on 160M. I wrote down the interference levels and then it took me awhile to put in the capacitors. I was fixated on tearing the capacitors out quickly and seeing if the interference was back to what is was originally to validate my test which they were. Knowing what I know now the levels seem to be very, very constant but at that time I was not sure.

I did not try the ferrite clip ons at the same time as they did absolutely nothing by themselves but it sure would be worth a try.

The sun is going away so I will try again tomorrow if I have good sun and constant values.

Ed W0SD

[Vic]

Hi Ed,

interesting test results ... about 20 Db reduction in noise signal is not bad for your first try.

RE inductors, you probably do not need a lot of L. If you had some powdered Iron cores (often painted red) this would porbably be OK. The most common Ferrites by far are type 43. This is a VHF material, and not very useful in the HF range. Type 31 ferrite material would probably be your best bet, but is is not common at all, and furthermore, there are almost never any marking on ferrite cores or clamp-ons, so it it difficult to determine the material with the eye.

Perhaps, as an experiment, you could try 20 or 30 turns of #10 solid (if possible solid) wire around a 1.5-inch PVC pipe or something, with capacitors at each end, this might be in the range of something useful. Solid wire is just a bit easier to work with, as it tends to stay put. You may find better rusults, later, if the inductors were divided into two sections, with capacitors at the center point of the coils. Use an inductor/capacitor set in the Pos and Neg leads of the CC It is possible that the noise currents in the capacitors might trip GFIs in some systems, but you probably do not have them. As your filter becomes more effective, you would need to pay more attention to coupling between the input and output of the filter, perhaps using a shield near the center.

As you know, each additional Db of attenuation of the noise tends to come at an ever-increasing cost -- diminishing returns.

Off to a meeting. Good Luck, please let us know how you do. Vic

[mike95490]

I doubt ferrite will work, as it will saturate fairly easily. I'm thinking some air core enamel windings, and low ESR caps. If you don't use Low ESR caps, you aren't going to see much effect. You have to stop the radiation from the long panel wires, right at the charge controller. Aim for Vmax of your panels +20%, that should be safe enough. What's the Array voltage again?

[Windsun]

I am somewhat surprised that the ferrites did nothing, as some of the testing I have done on other things, such as fluorescent lights showed a pretty good decrease in most cases. But there I only had two wires to worry about.

I suspect that the majority of the radiation is coming from the wiring to the panels, but it is also possible that some is coming from the battery temp sensor (have seen that on a Xantrex C-40). On testing that I did long ago, the controller to battery wiring was a fairly minor source - the batteries seem to swamp out a lot of it. But that was an older system, with a direct ground from the battery negative to a nearby earth ground post, which may have been part of the reason.

[tallgirl]

I am somewhat surprised that the ferrites did nothing, as some of the testing I have done on other things, such as fluorescent lights showed a pretty good decrease in most cases. But there I only had two wires to worry about.

I suspect that the majority of the radiation is coming from the wiring to the panels, but it is also possible that some is coming from the battery temp sensor (have seen that on a Xantrex C-40). On testing that I did long ago, the controller to battery wiring was a fairly minor source - the batteries seem to swamp out a lot of it. But that was an older system, with a direct ground from the battery negative to a nearby earth ground post, which may have been part of the reason.

The ferrites aren't going to do anything because dI/dt is phat and anything that can be put around the PV conductors isn't going to be able to store enough energy in the magnetic field (see "saturated") to help.

[niel]

guess everybody is against the ferrites, but you could still wind some air coils to try.

[tallgirl]

guess everybody is against the ferrites, but you could still wind some air coils to try.

Someone suggested winding around an iron core. I'm not against inductors, I'm just against pointless ones.