Radio Noise from PV System

niel

Re: Radio Noise from PV System

boB,
does this qualify for your request or is it a case you want it at the controller, but there isn't a battery connected in this case? from his original post:
" If I shut the breaker off to the four 205 watt 24 volt panels the "birdies" go away other than on 80 meters"

ed,
please do as boB asks as he designs mppt controllers. cover all bases and try connecting the negative lead as well and see if it is the same.

W0SD

Re: Radio Noise from PV System

Wow! Thanks a bunch for all the input. I am over-whelmed. I have read it all carefully and you can rest assure I will re- read it all several times and keep you posted. I think the test that I have been asked to do is to unhook the negative lead coming from the PV panels and see what happens to my noise level vs. having both leads hooked up. Since the breaker is just in the positive lead I am assuming I go ahead and leave the breaker on. Do I have this correct? If so I will do it tomorrow.

The following is from the Morningstar technical department. As many of you suggest it would be easier to start at a lower level than with the high levels I have with the FM80. Since I want to be able to operate my amateur radio station I need to get rid of the noise so as an intermediate step I am thinking of using a TriStar PWM (could have some RFI) but I can switch to the ON/OF mode with a dip switch and I think I have an excellent chance of no noise. I can run it in PWM mode when I am not operating the radio. Certainly with the MPPT it has come quickly apparent that getting rid of the noise here is not easy. I can see if every MPPT controller was built to make me happy the cost would go up, possibly significantly. However I think Morningstar and Xantrex are on the right path to at least meet the Class B standard.

My thinking right now (but I am debating) is to be able to keep using at least 2 of the 24 Volt 205 watt panels. I have six total panels right now with two in storage so we could deploy 4 panels to our first remote VHF repeater site and use the FM80 there as we don't have a problem on our input frequencies. I do have a problem here on some output frequencies I monitor such as 147.285 where the harmonic is almost exactly on frequency. This is some "wicked" stuff when the 24 khz switching can wipe things out at 147.285 mhz. That is the 6141
harmonic!!!

Even so the bottom line is I am not going to give up on MPPT (I like the idea)without a fight so I think I will wait for the new MPPT from Morningstar which should be available by December. Actually I may wait longer as I don't like to be a field tester and then see how much of a problem I have. I think I can be assured it will be a lot less than what I have now and then I can try some of these things that have been suggested here.

Looking at the e-mail it would appear if we are dealing with harmonics we are starting with a higher frequency and therefore they should
be farther apart making it easier to live with, ie affecting less spots in a frequency range. I would be interested on comments about this that
anyone could post.

Again thank you all for being so kind and helpful!!

Ed W0SD

E-Mail for Morningstar
.
Hi Ed,

Our TriStar PWM, SunSaver-MPPT, and new TriStar-MPPT controllers all meet
the FCC Class B standards.

Any switching noise from the TriStar PWM controller should only be at its
300Hz PWM switching frequency.

The TriStar-MPPT uses 3 phase switching at over 100khz (40khz per phase) and
while any interference will be at a low level, we can not guarantee a
totally noise free environment. However, we are very satisfied with the
results of our comparative testing against other well-known MPPT controllers
currently on the market.

Best Regards,

Noah Sindermann
Technical Support
www.morningstarcorp.com

niel

Re: Radio Noise from PV System

maybe boB can elaborate further, but i think he may want it done with the batteries connected to the cc input as you indicated you had it and touch only one of the pv leads to the input. my point was to try what boB wanted you to do, but do it for the other lead as well just for kicks as you never know.

boB

Re: Radio Noise from PV System

The reason I liked having the battery hooked up to the PV input was that it keeps the 25kHz current flowing. Just disconnecting one input by itself is also a good thing to try, but from my experience, the RF noise gets worse if you have at least some current at the input.... Up to a point anyway. So the battery can make that happen and then, the PV wires I suspect will make that common mode noise radiate, just one PV connector at at time.

Yes, touch both PV wires at the same time to one terminal. AND, you might try to connect them, first, to the PV + terminal, and next to the PV - terminal and see if they give the same results. I suppose I might predict the PV+ might make a bit more noise, but either one of those terminals probably radiate nicely.

And on the MS 40 kHz X 3 (over 100kHz) I would suspect that any birdies you DO hear, will be every 40 kHz. It may be though, that the stronger ones will be at 120kHz intervals, as the MF80 is stronger on every other 25 kHz one (50 kHz)

Did you notice anything like that, Ed ? Or do all the birdies peg your S meter ??


Class B is definitely a good benchmark for this stuff. I will try and get the Classic to be Class B as well, as soon as possible. I want to be able to use is for field day, myself !

boB

W0SD

Re: Radio Noise from PV System

Yes I definitely notice every other one is louder. Not a great difference but definitely noticeable. All the tests I ran were on the loader ones.
I will hook up the batteries to the PV inputs tomorrow and see what I find.

Ed W0SD

x_logo

Re: Radio Noise from PV System

Don't know if this will work for you, but...

I had some shielding issues on some power cables and tried a temporary shielding fix: bought a roll of aluminum tape found in the plumbing/air conditioning section of the local home improvement center, cut it lengthwise so it would neatly fit around the wire, wrapped a bare copper ground wire around the power cable then carefully applied the tape lengthwise overlapping it around the wire -- about 1-1/2 way around. Then, at the ends, folded the ground wire back over the aluminum a couple turns to get good contact with the outside aluminum and secured it with a wire-tie.

Seemed to work OK as a temporary shield. Your mileage may vary.

RFguy

Re: Radio Noise from PV System--TriStar and Class B notes

The TriStar at 40 kHz will have harmonics at every 40 kHz. 3 phase may give some sidebands if the phasing is unstable or if different clocks are used for the 3 phases.

As to the Morningstar MFG note:

This person is not an EMI expert. I have no criticism about his product or statements he has made except one I must take exception to. He should be cautious about blanket statements such as "there are no emissions avove..." which is an untrue statement as I explain below.

I sssume, as claimewd, that the TriStar unit was tested to comply with Class B FCC limits and passed. I further assume production units will also do so, as Morningstar is a reputable MFG in my opinion.

The FCC Class B limit (standard) allows nonzero emissions. Physically, a SMPS (which an MPPT is) has emissions from its switchiong frequency (40 kHz) on up. These harmonics usually exhibit a 1/f spectrum, dropping with increasing frequency. In many cases, the odd harmonics are stronger than the even ones. They exist and can be received as hass been reported here.

It is possible to filter the emissions so they are at or below the ambient noise floor. The military TEMPEST specs call for this with installations which handle classified (top secret) data.
However, it is impractically expensive for a commercial MFG to do so in most retail (or contractor) applications.

In a sensitive amateur radio application with long wires and sensitive receivers with big antennas nearby, merely passing Class B limits may not be adequate--or it might be adequate. Your mileage *WILL* vary! Fortunately, you probably won't have to filter the signals below the noise floor, either (at least most of the time.)

Bear in mind that Class B limits assume a typical (non Amateur radio) home environment where tabletop units with small antennas which are easily movble--and there's no guarantee against interference even then.

RFguy

Re: Radio Noise from PV System-try everything, sniffing out noise, build a mag. loop

BTW, in mitigating interference, "try everything." There are many. many variables.

It does help to understand what is happening from a physics perspective to help narrow down the cut-and-try testing.

A small magnetic loop antenna (shielded loop wit a cut in the middle of the shield and a 1:1 ferrite balun) attached to a sensitive receiver can often sniff out where the noise current is flowing.

To make the loop, use a semirigid 50 ohm coax (Teflon is best as it won't melt). At one end, expose the center conductor and short it to the shield. Make a 1/8-1/16" cut in the shield 1/2 way around the loop circumference (choose the size you want--smaller is less sensitive but localizes the noise better). Now make the loop and solder the shorted end of the coax to the coax shield at the beginning of the loop.

Finally, add a 1" long bead of 73 (LF) or 43 (HF-up) material on the other end of the coax, at least 2" from the loop and attach a connector. Make the shield contact 360 degrees around the connector to keep out undesired noise.
Dip in vinyl tool dip or use "liquid tape" to coat all but the connector.

Voila, a low-budget near-field magnetic probe!

W0SD

Re: Radio Noise from PV System

In reply to some posts the RFI is coming from the PV Input wires and the panel area. In the panel area is seems to be the PV wiring from the panels to the breaker box.

I would like to try a PWM Controller like the TS-60 but I am told that is not going to work with my 24 volt panels and I don't have any 12 volt panels so I am going to wait for the upcoming MPPT Morningstar(November ?) and try it. I can make this change even if is winter and I will report the levels comparing with the FM80 on the previous benchmark tests. If I need additional noise reduction that will have to wait for spring. Hopefully the levels will be low enough to not interfere at 14,000 khz and above. If the RFI does indeed turn out to be every 40 khz with them falling at about 14000, 14040 (odd-stronger), 14080, 14120 (odd-stronger), 14160, 14,200 (odd-stronger), 14,240, 14,280 (odd-stronger), 14,320, 14340 (odd-stronger) they would be easier to live with than every 24Khz where the even and odd harmonics were both a problem. Those lower than 14000 khz would be easier to live with as those frequencies I mainly use at night when the MPPT controller goes to sleep. If I did use these frequencies in the day time I could just shut the controller off during tha time.


Thanks very much for the input!

Ed W0SD

mike95490

Re: Radio Noise from PV System

W0SD wrote: »

I am going to wait for the upcoming MPPT Morningstar(November ?) and try it.

Maybe you can wrangle a test unit from Morningstar, or get a loaner XW60 controller from a vendor?

Is Midnight coming out with a solar MPPT controller ?

System2

Re: Radio Noise from PV System

hello w0sd;
this is don from nc.. i have had an outback system for about 2 years and recently got irritated enough to try to find my rfi problems
i have the same 24kc birdies all over the place when the chargers are working, the more they charge the louder the birdies..
i also have more problems than that; these problems stem from the 2 80 amp
mppt chargers, the 60 amp one seems to be quieter..
mine radiate every 15 kc or so past 30 mc; when you get on the last band of
my sx-28 hallicrafters it sounds like you are going by a picket fence; reception there and on standard broadcast is crap...
as long as the chargers have 24v going to them, the rfi is there.
i am going to get some rfi chokes try on the wires. and twist them.
also, the mate readout radiates at 15 kc spacing also, i suspect the
cat 5 cables are noisy also...

i have just started fighting my noise, if you have had other success, i would
like to hear from you!
thanks, don anglin..

Vic

Re: Radio Noise from PV System

Hi Don,

I am not Ed, but just as a review, here was my reply on the OB Forum:

>>OK, YES, the MX-60 -- the only OB CC that I have experience with does emit a lotta RFI. Believe that the FM is very much the same in this regard. Almost certainly, the noise is line-conducted. I would guess that mostly from the PV array, and on the PV conductors to the CC. Keep your antennas AWAY from the power room ( a bit late now, I bet). Use Ferrite common-mode chokes on the PV lines into and out of the CC. Run ALL conductors to/from the CC in pipe, grounded at the DC conduit box. A low-pass filter might help, it should be in a can with short leads for the capacitors. These capacitors should be stacked metal film, or other very low L units. Consider using several capacitors in parallel in each position of the filter.

Isolation of antennas from the power generation stuff, shielding/grounding of conductors, and filters are the best bet, BUT, really, the PV array will wind up being unshielded, and many arrays are fairly large, so, trying to isolate the antennas from the power facility is really important, if possible. Use Type 31 Ferrites for the common-mode filters, and work hardest trying to keep your low-band antennas away from the power stuff, as the largest emissions are at the lowest freqs, and any filters are., generally the least effective at the low freqs, and so on. And, the low-band antennas have the largest capture area.

When you do the work on the PV side of things (or at night), you will, almost certainly, hear switching birdies from the inverters, as well. So keeping the output of the inverters in pipe (or underground) should help attenuate these noises, as well. Forget if you noted weather you are grid-tied or not. Being off-grid probably worsens the situation. At my location have run the AC power lines underground, in pipe, and even used shielded cable for the AC runs in the dewlling (Coleman CorraClad). In the shack, AC is mostly in pipe, but some CorraClad there, too.

FYI, the Honda generators are great, but they, too, generate lotta hash on the lower bands, which can be dealt with as well.

All just MHO. Nice to see U here, Ed, and TU for SD in SS and other tests (think that you are the stalwart SD stn in SS and NS and so on). 73 GL Vic K6IC <<

Bottom line is, Isolation of antennas from all power conductors. Run all power concuttors in metal pipe -- EMT at a minimum. Use cast zinc connectors for the pipe.

Common-Mode filter all conductors at the source first, and at the load second. These steps have been very effective at my location. Have also used CM filters on the outputs of the inverters as well, also very effective.

73 GL Vic K6IC

BB.

Re: Radio Noise from PV System

When you put the cable through a common choke/inductor (ferrite bead, etc.)--remember to run them in +/- pairs... More than likely, just placing a bead on a single high current DC conductor will simply saturate the inductor and reduce its filtering effects to near zero.

-Bill

Vic

Re: Radio Noise from PV System

Yes, BB Bill, you are absolutely correct -- to me, it is not really a CM filter if both of the current-carrying conductors do not pass through the same toroid.

The first and best solution, if possible, is to isolate (separate) the antennas as far as possible from the power system conductors. This can become difficult with low band (long) antennas, unless one has quite a large property.

Thanks for the added detail, BB. Vic

W0SD

Re: Radio Noise from PV System

I have given up trying to cure the RF noise on the MX-80 Outback. There are some suggestions on how to cure it but none seem to work. It seems like I have yet to find someone who really has cured the noise which occurs every 24 khz.

Is there anyone who has has experience with the Morningstar TS-MPPT 60 or the Xantrex XW-MTT-60 on HF from 160 meters through 6 meters in regards to RF noise? SInce it has a class B rating is should be better.

It is my understanding that the switching noise from the Morningstar would be every 40 khz where on the Outbacker it is every 24 khz. That would be approximately half as many frequencies interfered with. Can anyone tell me what frequency the Xantrex XW-MPPT-60 switches at?

I would like to get some real world experience before buying either the Morningstar of Xantrex.

Thanks, Ed W0SD

Solar Guppy

Re: Radio Noise from PV System

XW-MPPT is 48khz single phase , the Tristar 45 is a dual-phase and the 60 is a three phase design, so their is a significant reduction in emissions due to the overlap of the phases

System2

Re: Radio Noise from PV System

FWIW I have the Morningstar Sunsaver 15 MPPT and it creates a lot of rfi in the 2 meter band. The higher the charge rate the higher the rfi.
THere was also a background hum when transmitting.
I suspected it was on the 12 volt power to the radio so I installed ferrites on the radio and that took care of the transmit hum but not the interference when receiving.
It was coming in on the antenna. After some "sniffing" with a hand held scanner I found the culprit was the leads between the sunsaver and the panels. ( two 100 watt panels)
Even the panels themselves were radiating. Since I am in a truck camper I can't get a lot of seperation between the antenna and the panels.
I got the MPPT because it was reported to be FCC compliant and didn't create a lot of interference.
I have been following this thread and have gotton a lot of good information. I will try winding a toroid and using a couple caps. I don't have much room to work with but I will see what happens.
-Bill-

Vic

Re: Radio Noise from PV System

Hi C Bill,

I'd think that interference on the 2-meter band should respond well to a ferrite core as close to the charge controller PV input as you can get it. Type 43 material would probably be best. Should be a Common-Mode choke where both of the PV conductors pass through the core -- assuming that you have only two leads from the panels. This should at least help some ... next, you might want to try an additional CM choke on the battery leads as close as you can get it to the charge controller, if the reduction from the CM choke in the PV leads was not adequate.

There could be ground loop issues, where the coax shield is grounded to the body of the truck/camper at the antenna and so on. I assume that your 2 M antenna is an omni vertical. If you could disconnect the antenna, but leave the feed-line in place all of the way to the point where the antenna was connected, this might help elinimate a ground loop in the coax as a possible problem.

Good Luck, please let us know of your results, 73 Vic

System2

Re: Radio Noise from PV System

Vic, thanks for your suggestions.
I wound two CM chokes and put them on the panel and battery leads at the controller. This took care of a lot of the noise but not all of it. Right now it is at a liveable level.
Caps had no effect. Since this is a truck camper I have no "earth" ground to lead them to and across the leads had no effect.
My next step will be to change the wiring of the panels. They are now wired in series and I am curious if the step down in the controller could be playing some part in this. I will try a parallel route and see if this helps.
As to the ground loop issue my antenna is indeed a vertical but it is a mag mount with the lead molded in. I will isolate the mount and see if that helps.
I will post my results as i get them. THanks again for your help.
73 -Bill- N6TF

System2

Re: Radio Noise from PV System

I finally found the time to get on the roof and wire the panels parallel instead of series.
Series voltage was around 40 volts. Now the panel voltage is 20 volts, lightly loaded. The interference is now gone.
I guess the greater step down in voltage was causing the controller to work harder.
Anyway, thanks for everyone's help.
-Bill-

halfcrazy

Re: Radio Noise from PV System

crazybill wrote: »

I finally found the time to get on the roof and wire the panels parallel instead of series.
Series voltage was around 40 volts. Now the panel voltage is 20 volts, lightly loaded. The interference is now gone.
I guess the greater step down in voltage was causing the controller to work harder.
Anyway, thanks for everyone's help.
-Bill-

That RFI gets a touch stronger when I run 250 vdc into my charge controller compared to 100vdc. The Good news is the Classic is pretty darn good and looks like it should pass Class B without modification. boB has worked very hard to make this thing quite and it looks like it will pay off. I have one 2 feet from all my ham radios including my 6 meter repeater and 0 noise.

niel

Re: Radio Noise from PV System

now that's something i never thought of is the levels increasing with the voltage. does the noise increase linearly or logarithmically? i would think linearly. how about the current's influence?

i did hear a bit of rfi from my classic, but it was far below the receiver noise to ever worry about and should it ever get to the point of being annoying then there is no great difficulty in putting chokes on the input and output. so you ask, how do i know it was there? because it was roughly every 50khz and when i shut off the cc i can hear it disappear. ftr, the powering down of the classic was physically shutting it off of power and not the on/off ability of the cc. i didn't try it that way as the classic is unigue with being able to shut it off at the cc, but no matter.

one also tends to forget that a cc can not only emit, but it can receive rfi from a high powered rf source. any noticeable quarks from this aspect from anybody as i operate 100w or less anyway? my old sb50 did act goofy when i operated with greater than 50w or so on hf.

an example of the power rf can inflict is some of my ccd cameras went down for all that were routed parallel to my ladderline 10ft away. i thought it was the cameras themselves getting a spike, but it blew out the small wall adapter switching supplies. i have since put toroids on the ps output leads, but haven't put it through its paces. i guess i may need to come up with a better centralized supply rather than many wall adapters. i'm thinking in the area of about 5a may be good, but if i get any more cameras with leds i may need more current. any ideas on a cheap switcher in that 5a area guys? linear would be easy to do with ic regulators, but linear runs hot and is wasteful.

nsaspook

Re: Radio Noise from PV System

niel wrote: »

i guess i may need to come up with a better centralized supply rather than many wall adapters. i'm thinking in the area of about 5a may be good, but if i get any more cameras with leds i may need more current. any ideas on a cheap switcher in that 5a area guys? linear would be easy to do with ic regulators, but linear runs hot and is wasteful.

I use a modded CCTV power supply panel for my cameras and controllers. I installed a power change over relay that normally uses the 12vdc supplied from the PV system storage battery to run the outputs but will auto switch to the internal 120vac 12vdc 10A switching supply if plugged into a AC socket. I also added 3 5vdc regulator (7805) outputs on one of the supply boards for some cameras and controllers that needed that voltage. I plan to use some of the outputs for interior led lighting circuits.

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The build quality is fair but for the price it's a good deal.

MiamiSunrise

Re: Radio Noise from PV System

I've found this thread very interesting.. I'm a ham myself and have a lot of customers who are, and they're looking for quiet controllers.

I had fairly good results with squashing the VHF noise on an OutBack MX60 by just putting some poly film bypass caps out of my junk box between PV+ and B+ and negative ground, and grounding the housing well. It would definitely be worth running all wiring inside metallic conduit / BX cable / Greenfield / etc. for as much of the run as possible, with the conduit well bonded to ground.

I have thought of using series inductors to form a full L-network lowpass filter to keep the controller's internal hash at bay, but the need has not yet arisen.

I would say that the PV array and its wiring are probably the most likely parts of the system to cause you trouble. Radios often have some filtering on the DC input, intended to reduce alternator whine, which may help you out a bit... but the PV array and wiring act like a monster of an ANTENNA, radiating the crap out.

I have done some really crude work in designing an inline filter in a nice shielded metal box to deal with MPPT QRM... one of my early efforts is built in a conduit box labelled "SUN-MPPT-STFU-80". Unfortunately it's hard to get a particularly beefy inductor together that'll deal with 80 amps without introducing a lot of cost, weight, and/or resistive loss. Yuck!

I've seen common mode filters mentioned in here, but I'm kind of suspicious of that being highly effective, as the MPPT controller's noise may not necessarily be common mode at all and the DC - side is often grounded. This makes it an unbalanced system. My efforts have been basically to treat each wire as the live conductor of an unbalanced feedline, paired to system and earth ground. It seems to work well but leads to a rather complicated and clunky filter.

I did notice that there is some filtering circuitry visible inside the Xantrex XW-MPPT-60-150. I strongly dislike those controllers for a handfull of reasons, but they're the only ones I've seen that have chokes and caps to kill the QRM.

I'd like to try out a MidNite and see just how quiet it is. If they work well, I can finally stop recommending to hams that they leave themselves stuck with PWM controllers on their systems!

Vic

Re: Radio Noise from PV System

MS,

Regarding the RFI from the MPPT CC:

Using EMT with compression fittings for ALL PV and battery conductors, or all Rigid pipe works failry well. BUT, actually, if the Ham can separate antennas well from the PV array and power conductors this may be the best, as, the PV array is a "Panel Antenna", and large arrays have long, antenna-like conductors.

One Common Mode choke, -- Type 31 material, using a stack of three or four 2.40" diameter Toroidal cores, works quite well for HF -- 160-6M. For VHF/UHF only, Type 43 material should be better.

It is important to pass EACH conductor from the PV array through the stack of cores -- bifilar-wound. The purpose of passing the PV ground conductor through this core stack is to keep from saturating the core, which causes it to lose its inductive properties. It is a very good idea to place this CM choke as close as possible to the CC, and to place it in a tight metal box. If this filter does not attenuate the RFI well enough, then, placing an identical filter on both battery leads can help some, just place it close to the CC, and in a box. ALL wiring needs to be in TIGHT EMT or Rigid pipe.

Once this is done, and hopefully works well/fairly well, one will then hear other NOISE from the inverter(s), and other things. A similar stack of Type 31 cores for the inverter(s) and running ALL power conductors in metal pipe, also works very well. PVC pipe runs under ground at about 24" seems to be as good as metal. Here, The combined noises are below the S 0.5 average noise level on 80/75 Meters.

With rising frequencies, one would expect more attenuation from any of the above approaches, altho Type 43 material is better at VHF/UHF.

Had wanted to run a test of the X MPPT-150 SCC (as it claims FCC Class , but it had a factory bug, which requires my buying doo-dad (or renting one), which does not seem very friendly of Schneider, to not disclose this for a "field Fierware updatable CC", and it is a Factory BUG -- the CC lies about it's charge mode. Guess my days of buying their products have passed.

JMHO, 73 GL Vic

niel

Re: Radio Noise from PV System

1/2 s unit? i don't think i've ever seen the s meter that low on 75/80m without an attenuator inline. as i said i audibly heard it in there, but it was in the background noise. i use no emt for pvs or coax for the antenna (with 450 ohm ladderline and close proximity to the pvs) as i have all open wiring. no problems in this arrangement and if i ever put up another antenna farther back on my property with 75 ohm coax then i suspect i won't ever know it's there at all. of course i'm not feeding much in pv watts at this time either so i may need to update my findings in the future.

MiamiSunrise

Re: Radio Noise from PV System

Oh my stars THANK YOU. THESE THINGS WERE DRIVING ME INSANE.

I would read one set of behaviors from the unit's display or XW SCP and observe totally different readings on external meters... The only thing that was ever *correct* on the displays was the number of watts. I thought I was just losing it.

Xantrex never sent us any sort of service bulletin... of course... ya think being a major distributor will get you any such special favors in this day and age? :grr

What is needed to perform the upgrades, the XW System Configuration Tool? I know I've got one of those sitting around...

Vic wrote: »

MS,

Had wanted to run a test of the X MPPT-150 SCC (as it claims FCC Class , but it had a factory bug, which requires my buying doo-dad (or renting one), which does not seem very friendly of Schneider, to not disclose this for a "field Fierware updatable CC", and it is a Factory BUG -- the CC lies about it's charge mode. Guess my days of buying their products have passed.

JMHO, 73 GL Vic

Vic

Re: Radio Noise from PV System

Hi MS,

I do forget exactly the name of the "tool" that is needed. It is not the SCP, as X/S seems to want one to buy MORE of these do-dads. It is some kind of Implanter Tool. It costs about $240, plus shipping.

The new XW MPPT 600-80 HV CC needs BOTH the SCP (as it has NO LCD at all, just a few LEDs), and this implanter tool (if a FW update is needed). These two do-dads total about $500. This is not so much of a problem for an all XW system, as the SCP is needed to do some things on the inverters as well. BUT, for a stand-alone application, it is a deal-breaker for me.

The FW Implanter seems to me to be a Brain Dead idea. There are much better CCs than the XW SCC-150. The Midnite Classic promises to extend the genes of the OB MX-60.

Thanks, VIc

Vic

Re: Radio Noise from PV System

niel,

Glad that you have no CC generated noise to speak of.

Have mentioned in the past that I have not taken the scientific approach to noise mitigation. Have simply assumed that the CCs and inverters Will generate noises, and have chosen to do everything reasonable at the beginning of doing the power system to try to reduce the RFI.

IMHO, it should be the current levels that a CC is dealing with has a strong influence on the magnitude of the noise. As noted above, the CC input voltage seems to have an influence as well. The solar array here, while not huge, spans about 34 feet on a roof-top, so that effective array should be an effective transmit antenna for noise, and it is in the clear, and is quite visible to the recieve antenna(s). If I had to guess as to the most effective first step in noise mitigation, I'd guess that a large CM choke may well be it, followed by shielding (in metal pipe) the PV leads. Actually, running the PV wiring in tubulay braid should be as good, but just not to code.

Looking an the AC outupt of the SW+ inverters, shows that each step of the sine wave has HF noise imposed on it, so the inverters are a farily large contributor to RFI. And, low band wire antennas are large, and have a large capture area, particularly horizontal antennas, as much power wiring is horizontal ... and so on.

Ladder-Line feeds, if truly balanced, should not pick up any noise, in theory. And, some, like myself place some twists in the LL, which should help reduce any LL pickup. 73 For now, Vic

niel

Re: Radio Noise from PV System

when i increase what i have in pvs i'm sure the noise will come up some if i stay with my present antenna setup. unfortunately, few antennas are perfectly balanced due to many factors and that will allow some pu. i do the twisty thing too.8)