Radio Noise from PV System

jaclement

Re: Radio Noise from PV System

Perhaps placing the panels in parallel rather than series made a smaller radiating antenna of the panels themselves.

niel

Re: Radio Noise from PV System

jaclement wrote: »

Perhaps placing the panels in parallel rather than series made a smaller radiating antenna of the panels themselves.

that won't matter much as rfi isn't like battery voltage, but going parallel may still vary the resonant frequency a tad and the end result of that would still be noise on a large spectral area. it's not worth the trouble of doing.

MiamiSunrise

Re: Radio Noise from PV System

For all the things I hate about the XW-MPPT.... yes, it does have good noise suppression. >.<

I'd still go with the MidNite Solar Classic, though. After seeing a wave of XW-MPPT's come back having suffered Capacitor Plague issues on the control board, and noticing the TINY pins that the 60 amp DC current has to pass through, I got kinda turned off to them.

MiamiSunrise

Re: Radio Noise from PV System

....wait, what

"Firmware Implanter"

I opened up a sample of the XW MPPT 80 600 that Schneider sent over and I WAS NOT IMPRESSED. The construction techniques used within, to me, are totally unacceptable for something containing high voltage - let alone high voltage AND high frequency switching. Nice try, Schneider... I use the thing now as a podium to set my laptop on when I'm working. I do not have the courage (or "firmware implanter" apparently) to try hooking it up.

It actually came to us with some of the internal cables unplugged and dangling loose inside.

Vic

Re: Radio Noise from PV System

Hi again MiamiSunrise,

Thanks for the info on the Schneider/Xantrex CCs. Disappointing on both counts.

Large corps seem to be way too cost-consious. My "old" POS XW SCC was made in China. And that is probably why it came with BUGGY, OUT OF DATE FW -- long supply chain.

Seems that S/X just tries to meet about 50% of what the market wants. They could care less about the rest of us. Basically, they provide no competent support, as far as I'm concerned.

I forget the exact nomenclature for the FW Implanter. It is some sort of "tool", and is about $250-ish.

Too bad abut the design issues with the XW MPPT 80/600 (or whatever it is called). That could be a neat solution for some of us. Did seriously look at it, but have such a FOUL taste remaining from the lack os customer support they have evidenced on my XW SCC, (among a few other things) that I could not stomach the downsides of probable lack of support for a unique product ... one cannot just sub in some other mfg's CC while the 600 V CC might be in for repair.

Still feel really screwed by them. Stuck with a disfunctional POS CC. They could care less, they got their money, and I refuse to buy/rent the FW Implanter, to fix the BUG in the FW that renders the "CC" disfunctional. And the reseller who sold it ot me was also uselsss.

Hate to rag on Schneider/Xantrex, but they have worked very hard to earn this level of respect. I keep up this diatribe, in an attempt to try to encourage others to be a bit cautious about the after-sale "support" from Schneider. You bought it, you own it, have a nice day, we choose to do nothing for you, seems to be their company line.

YMMV, . . Vic

MiamiSunrise

Re: Radio Noise from PV System

Haha. Recently I had my first, uh, fun experience with using the XW System Configuration Tool.

Having all sorts of drama getting it to work on a modern PC using Windows 7... I have determined that it will be necessary to find an old 32 bit Windows XP or 2000 machine to make it happy! The problem is with the drivers, they do not work on a Win7 64 bit system AT ALL. I managed to find drivers from the manufacturer of the actual interface, and with those loaded I can get in and change config settings, but firmware updates simply never get sent over the RS485 buss. It just sits on its iBottom.

I dunno man... having a current product offering that requires a computer from 2006 to successfully program or update it is kinda wacky.

Meanwhile, I can give the Phocos CML, Dingo, CIS, and CXN controllers a clean bill of health when it comes to RFI. Both are small PWM controllers, switching frequency is fairly low and the switching is clean. I tested them next to an HF radio and couldn't hear 'em. Good Enough For Government Work

mike95490

Re: Radio Noise from PV System

and here's my experince with the gateway, to upgrade firmware:
http://forum.solar-electric.com/showpost.php?p=103722&postcount=7

bricked the gateway, can't wait till it gets back, and then I'll try for the SCP, if it's OK, I'll try the inverter. That will cost to ship it back as a brick!!

Vic

Re: Radio Noise from PV System

Noise ?!?? ............ VB

65DegN

Re: Radio Noise from PV System

You might try getting a hold of a yoke from a TV that has a CRT. Remove all the wire from the yoke and make as many turns through the yoke as you can with the cc input wires.
Sometimes this will swamp RFI.

niel

Re: Radio Noise from PV System

65DegN wrote: »

You might try getting a hold of a yoke from a TV that has a CRT. Remove all the wire from the yoke and make as many turns through the yoke as you can with the cc input wires.
Sometimes this will swamp RFI.

that's if one is available to those that know what you are talking about. for those that want to skip the search for a yoke core either due to unavailability or unfamiliarity then you can buy the cores fairly cheap.
http://search.store.yahoo.net/wind-sun/cgi-bin/nsearch?catalog=wind-sun&x=0&y=0&query=ferrite
if you can't wait, then go to radio shack and see if they are still stocking them. i know they carry them online, but the cost of them is at a premium in price.

Vic

Re: Radio Noise from PV System

BTW, just noticed on the Midnite Forum, that the Classic CC has passed FCC Class B. So, now there is another CC with low emissions, certified:

http://midnitesolar.com/smf_forum/index.php?topic=427.0

FWIW, Vic

niel

Re: Radio Noise from PV System

yes, you mentioned that in your other post. hey, boB's a ham and knows what the score is.:D

Vic

Re: Radio Noise from PV System

niel,

Yea, and boB has been saying for about a year, that he thought that the Classic should be a fairly easy pass on CL B, guess he was correct.

Sorry for the double post ... thought it might be too obscure if it was here only, but is relavent. If this 2X posting is a no-no, please DELETE the post in the Review/Opinion section. Perhaps, I could even delete it myself ... Thanks, Vic

Vic

Re: Radio Noise from PV System

Some DC Common-Mode Chokes into/out of Ccs. Vic

niel

Re: Radio Noise from PV System

that's good that you are showing the chokes with as many loop throughs as you can get. that makes it more effective.

btw, don't you think you should get that stuff off of the inverter vents?:p

Vic

Re: Radio Noise from PV System

Hi niel,

YES, and at that they have been pulled to the right with zip ties, altho, this pic was just after threading a lot of 6 AWG over, under, around and through that area. and they moved a bit. I had considered the air flow restriction, and tried to do as much as I could.

The inverter fans almost never run, except during high-rate -- 150 A, charging. I will be leaning on these inverters more than the set at the other location, so the fans may well run for higher AC loads. However, this power room will be A/Ced which should help.

The two large CM Chokes are the largest that I could ever make, as those toroidal cores are custom-made for a specialized gizmo. It is quite possible that they are considreably larger than needed. This is an experiment. The two small ones on the right, are smaller than I usually use, as had only two of the known type 31 2.4" cores. So may get more of the T31-2.40s and make the small ones larger, and the large ones smaller. Have reserved some additional wire at the right side of the box.

Will do some measurments. But your observation is dead on. That DC box is too busy. Had planned to place those cores in a pull box above the X DC box, and may still ... just testing. Thanks, Vic

niel

Re: Radio Noise from PV System

i guess it is kind of a busy box now isn't it. i dare not take this any farther than i just did.:p

PNjunction

Re: Radio Noise from PV System

My 12V solar setup is basically just to run various HF receivers 160-10 meters, and have no noise to report with Morningstar Sunguard, or Sunsaver PWM controllers.

The controllers are very close to the antennas, about 5 feet away, and still no noise. I was fearful at first thinking I would probably have to live with on/off shunt controllers, but when I spun through the bands with the morningstars, I threw the shunt controllers away.

The receivers are connected directly to the battery, and not attached to the CC load terminals, so I haven't tested them from that since I won't be using the load terminals of the CC.

I'm very happy with the pwm controllers, as some references cast a question about pwm being noisy by default - I'm not so sure this is true. At least my receivers don't think so. Mppt can be a different story as read in previous threads, but so far so good with the little Sunsavers.

bmet

Re: Radio Noise from PV System

my sunsaver does csuse interference in my radio and cassette tapes, but only in one channel. the radio is connected via dc directly to the battery bank

PNjunction

Re: Radio Noise from PV System

Wow, my Icom R75, and Alinco DXR8T seem to have no problem.

What kind of radio are you using, and how long is the dc run from the battery? Are you hearing some sort of pulsing? If not, perhaps your panel wiring is acting like an antenna itself, and the noise isn't from the Sunsaver per-se. Is the noise consistent across a broad spectrum, or only on specific frequencies? Are we talking HF, or maybe the am broadcast band? I'm assuming you have definitely nailed it by disconnecting everything, including the Sunsaver, and tested by only running from the battery and that single run of dc back to your receiver....

I'll borrow a friend's Yaesu FT-897D portable, and take it right on top of my Sunsaver with a pair of cans and see if I can force the issue to hear it myself.

niel

Re: Radio Noise from PV System

actually some noise appearing at some frequencies is normal. it depends on many factors and the noise just may be below your radios noise floor and is why you don't hear it, which is a good thing. it does not mean that somebodies stuff, be it ham or solar, is defective if it appears even though it is undesired.

PNjunction

Re: Radio Noise from PV System

Borrowed the 897D transceiver and ran some quick lunch-time testing..

With the transceiver running on it's own power, I heard no noise coming from the solar setup with the sunguard or sunsaver PWM cc's.

With the transceiver sharing the same battery as the CC's, I was extremely pleased not to hear any broadband hash. However, I was able to track down a small number of noises coming from the CC, although I think it is from the supporting circuitry, and not PWM itself, which for the morningstars are a duty cycle on/off switch up to about 300hz which is basically audio. I discharged the batteries a bit prior to the test to make sure that the duty-cycle would be active. Being able to quickly connect/disconnect the CC and switching amongst internal and external power on the 897 made it easier to identify.

During the short test time available, I was able to identify an unstable CC buzz with the same characteristics on 2.034 Mhz, 3.775, 7.083, 14.160 mhz. There were quite a few weaker ones up in the 10 meter band which I didn't log. Still, with only a small handful of freqs to deal with, there is NO way I'm going back to the 1980's non-temperature compensated on/off shunt controller. I normally don't run from batteries that are under charge anyway, so it's kind of a moot point, but I wanted to know anyway.

I might end up doing some rf-choking and capacitor bypassing, but I can easily live with just a small handful of problem freqs that I don't use anyway. My biggest fear was broadband hash, and that is really not the situation here. Whew!

niel

Re: Radio Noise from PV System

that is good news of it not be a problem for you, but the tests weren't necessary as i knew there was some to be found if one looked for it. i simply said that no mppt controller is noiseless. i never implied for you to go pwm or intended to badmouth all mppt controllers. my point is that it is simply a fact that there is some noise and does not mean that there's something wrong. even some layouts could exacerbate the noise that is there. in some cases it does fall onto desirable frequencies with enough strength to warrant further efforts.

daniel

Re: Radio Noise from PV System

Hello:

I have come to the conclusion that it is a really bad idea to put ferrites on the wires going into or out of the charge controller. These ferrites increase the inductance of the wire and if they are large enough they can stop the FET transistors from turning on and off correctly. It would take fairly large inductors to work with a high current system but even small ferrites are going to make it harder for the FET transistors to switch.

Daniel

Vic

Re: Radio Noise from PV System

It is good news that you are happy with the noise profile of your PWM CCs.

Would guess that the more power that the CC is delivering to the batteries has an effect on the PWM noise. PWMs should be fairly quiet, but fast edges lead to improved efficency, but fast edges can also cause noise issues.

Often the polarization on the receive antenna, its capture area -- relative size, proximity to PV array and so forth are large factors. This is a large factor in Line-Conducted noise.

PN, you may be measuring mostly Radiated noise.

Often, True SineWave Inverters create more noise on HF than PWM CCs.

As an aside, many 12 volt HF transcievers do not make full power when operating from 12 volt batteries which are not under charge at that time ... some are much better than others. Some have very poor transmit IMD specs when Vbat is below 13.5-ish volts. YMMV, Vic

BB.

Re: Radio Noise from PV System

Welcome to the forum Daniel,

I tend to think that the whole ferrite on controller leads is a bit more complex...

First, there is the ferrite materials. Ideally, you want to look for "lossy" ferrite material used to control RFI/EMI emissions. "Good" or low loss ferrite is great for transformers/inductors because they have no losses. But using this material to control EMI--The low-loss ferrite + wiring can "ring like a bell". Lossy ferrite will dissapate energy and reduce the chances of ring (high Q vs low Q materials).

Next, the way you pass the wires through the (typically) donut ferrite core.

You can pass one wire through the donut (or even wrap a single wire a couple times through the donut hole). This will not usually work well for DC currents. The high current flowing one direction will tend to saturate the ferrite and reduce any EMI control effects. Also, this add inductance the cable and could cause problems with the FETs.

Another is to take two wires (+/-) and pass it through the donut (and possibly wrap a turn or two through the donut). This is a "Common Mode" choke. This is good a blocking signals traveling down both wires at the same time (in phase). This also should not create problems for the FETs (the "differential" inductance cancel each other out). This also works well with differential DC current flow because the +/- current flows cancel each other out and will not saturate the ferrite.

-Bill

boB

Re: Radio Noise from PV System

daniel wrote: »

Hello:

I have come to the conclusion that it is a really bad idea to put ferrites on the wires going into or out of the charge controller. These ferrites increase the inductance of the wire and if they are large enough they can stop the FET transistors from turning on and off correctly. It would take fairly large inductors to work with a high current system but even small ferrites are going to make it harder for the FET transistors to switch.

Daniel

Daniel, how much inductance do you think would be a problem ?


What happens to the FETs turning on and off with too much inductance do you think ?

Thanks...
boB

PNjunction

Re: Radio Noise from PV System

Ah, great information all! I really appreciate it since I understand how hard it can be to provide the most accurate answers without just blasting out a blanket-statement - every install / situation / usage pattern is different. In the end, it is still my responsibility to apply the answers received and see if it fits my own scenario. Fortunately, you guys are right on the ball for the most part!

Guess what was on my CC leads? Yep, HF-spec ferrites. I'll take them off and do some more testing later. I'm very familiar with common-mode rejection since some of my antennas have the common mode filtered, whereas some actually make use of the common mode - it all depends on what you want to do. However, I really wasn't thinking DC, and will investigate the additional inductance / saturation aspect with regards to the CC operations. Nice tip!

I love experimenting, and sometime later I'll probably get an mppt just to play with it, even though it isn't really necessary for me right now. No badmouthing taken at all. And nobody is on the hook so to speak for their responses since one size doesn't always fit all.

BB.

Re: Radio Noise from PV System

If you can run the electrical wiring in metal conduit (grounded to the source of the noise, such as the charge controller) will help too... About 10-15' of conduit (or shielded cable) is about the maximum "helpful" length. Any longer shielding will not make much difference (most RF energy has been "shorted" from the cable to shield by this point--And the natural impedence of the cable does not carry RF signals past this point).

-Bill

daniel

Re: Radio Noise from PV System

Hello Bob:

Well if you wanted to use an a ferrite that was large enough to work with 44 amps of power, like I have on my MX60, I think it would be quite large. A electronic design engineer informed me that any ferrite put on the wire would change the inductance on the wire and it would directly affect the opening and closing of the FETs. His advice was to talk to Outback and see what they recommend. I think when you twist the wires this also increases the inductance and I am going to ask Outback about this as well.

When I put a ferrite on either the input or the output lines to the MX60, the signal causes the ferrite to become magnetized and I didn't expect this to happen. It does sound logical. Also when I put the probe of my scope on the ferrite I get a really good signal so the ferrite is absorbing rf from the line.

My electronic design engineer friend likes Bill's idea about using a donut choke and having both wires go through the donut. This is as opposed of having individual ferrites on each wire.

Measuring the interference isn't easy. It seems easier to measure it with a radio as opposed to a scope or spectrum analyzer.

Best Regards,

Daniel