Advice about solar PV panels

Discussion in 'EMC Matters' started by MM5AHO, Dec 14, 2014.

  1. MM5AHO

    MM5AHO New Member

    I'm considering installing about 4kW of solar PV panels on my roof, and wonder about RF HF emissions from the inverter.
    Anyone have any advice on this for me?
  2. Ken G3SDW

    Ken G3SDW Moderator

    Sorry for the late response Geoff, i will come back to you with some suggestions of makes to go for and some other tips to consider.
    73
    Ken
    G3SDW
    EMCC
  3. Ken G3SDW

    Ken G3SDW Moderator

    One other comment that i forgot to mention, you say that you are considering to install, do you mean your self?
    73
    Ken
  4. MM5AHO

    MM5AHO New Member

    Ken

    thanks for your reply - it's not a "late response" - I only posted yesterday. I'm grateful for any responses!

    I'm not considering self installation, that endangers feed in tariff system, but to have a system installed by an authorised installer.
    I imagine the DC side not to be too much problem, but I do fear having a large inverter sitting in my roof space. I have 4 or 5 runs of coax through there to my antenna systems which are within 5m of roofline, and the last thing I need is 50 Hz buzzing all over the HF bands. I'm quite keen on weak signal work!
    Like SMPS's, I imagine that some inverters are better engineered than others, some might not have the filtering components "Cost engineered out". I once bought an inverter generator for use on my boat (/mm), absolutely useless. Added all manner of filtering; halved the problem, but still S7 noise. Yet I know that Honda generators, which cost a lot, do not cause this problem!
    There might be cabling variations that might help in installation too I guess? Shielded cables might not normally be used, but might be specified?
    Regards

    Geoff, MM5AHO
  5. Ken G3SDW

    Ken G3SDW Moderator

    Geoff, i always try to reply on the same day so for me the second day is a no no. Right take a look at this guy G3PGA on QRZ.com, scroll down to the bottom of the page and read about the way he has gone about Solar PV, he has had a great success, proving it can be achieved.
    When you approach an installer ask them to what regulations they will install it to? and remind them about your concerns on RFI.
    By listening to there respective replies you will be able to tell if they are capable or not to do the installation to your satisfaction. All of these details need to be put in a written contract.
    By reading the info on the G3PGA QRZ.com page you will see that it can be done.

    Keep in touch
    73
    Ken
    G3SDW
  6. MM5AHO

    MM5AHO New Member

    Ken

    thanks for your help. That's an interesting read anyway, but the PV info very valuable.
    I've heard of big differences in RF emission from various inverters. Before agreeing to anything, I'll want to take a RX to a couple of existing installations and test.

    Thanks again

    Geoff
  7. Ken G3SDW

    Ken G3SDW Moderator

    It would seem that ones made in Germany come out the quietest as opposed to the ones from PRC do not, why dont you sens an email to G3PGA for his comments.

    73
    Ken
  8. MM5AHO

    MM5AHO New Member

    Ken
    Thanks for further info. I've already made contact with G3PGA, most helpful.
    I intend to get three quotes, and now feel I've got the right questions to ask. Its an industry with fairly low costs of entry, which means that there are some cowboys in it. But there also some competent operators, and it should not be too hard to sift the "wheat from the chaff". I just hope I don't have to much sifting to do!
    I note that on G3PGAs installation, he asked for ferrites to be fitted on the cabling, and from the images they are only on the DC side. Mike doesn't have all the details of what they did, but his story combined with the images seem to tell most of the story.
    It looks to me as if they have replaced one larger unit with two smaller ones (the 3000 vs the 2000), and at a stated 3kW capacity I'd guess that at times the 3000 was working to capacity. (assuming 3000 = 3kW?) Whereas two x 2000's would have some headroom. The ferrites on the DC lines (which must form a reasonable radiating antenna running through the roof space and round the panels), would help block RF from radiating that way. I'm not sure if RF might also leak back into the mains via the AC cabling, and wonder about ferrites there too.

    In any case, the circuitry of the inverter is very important. I note the huge difference between 12V DC mains inverter PSUs available. Some are virtually RF silent, some S-meter bendingly loud! Examination of the main board of many appliances these days can often reveal the missing component makings, and a bit of figuring of the circuit show that these were probably originally there for suppression, but no longer fitted. The cynic in me might think that they were fitted from examples sent for EMC testing of the design, or for CE marking design compliance checks. But a few small components missed on thousands of units made can be a saving for the manufacturer.

    CE marking to the Germans means something other that "Chinese Engineering".

    As I've yet to have a "site survey", by my bidders, I'll raise the question quite pointedly with each quoter and see what happens. I'll post some feedback on my experience. Might help others considering solar PV. I hope I don't have the saga that G3PGA had. I'm unlikely to suffer as he has, but I don't really want to write a blog. But I will write up my experience.
    Geoff
  9. Ken G3SDW

    Ken G3SDW Moderator

    OK Geoff, that sounds very good and you seem to now have found the questions to be asked and yes there must be and are cowboys doing some of this and the way you are going will sort them out.

    As for ferrite`s then it is a case of belt and braces, if in doubt spread them about.

    Thanks for coming on to this forum, it makes others aware of problems and helps them to make good decisions on how to go about minimizing RFI from Solar PV and on a broader note helps solve all other EMC problems they may have.

    Look forward to hearing from you with your experiences on the forthcoming installation.

    73
    Ken
    G3SDW
    EMCC
  10. gm3sek

    gm3sek New Member

    Geoff, our neighbour has a large installation with a single inverter made by Fronius. His workshop is right underneath the roof and he listens to MW radio with no trace of interference. 200m away, there is also no interference here on any band up to 144MHz. This was from a Scottish installer somewhere in the Central Belt, so I will get the details and let you know.

    The key points seemed to be to have DC-only wiring outside on the roof (no micro-inverters or switch-mode "optimizers" outside on the panels), and an inverter built to industrial rather than domestic standards. This particular inverter is a wall-mounted unit in a large metal case, and although I don't know for sure, I'd bet on it having industrial-style filtering on both the DC input and the AC output. The manufacturer was Fronius - yes, sure enough, it's from that country where "CE" really does mean something.

    More details later today, if the neighbours are in.

    73 from Ian GM3SEK
  11. Ken G3SDW

    Ken G3SDW Moderator

    Thanks for making you comments on this forum, this is most appreciated Ian. The forum is designed for this sort of thing, to get other members involved with sharing experiences on all aspects of EMC problem.

    Once again thank you.
    73
    Ken
    G3SDW
    EMCC
  12. gm3sek

    gm3sek New Member

    The supplier was Solar and Wind Applications Ltd, http://www.solarwindapplications.com/ Although based in Ayrshire, they supply and install all over Scotland, and the website says that they still install Fronius inverters.

    Telephone 01292 591 000. The owner is Rod O'Neill and the person who knows about electronics and interference is called Martin.

    They also just received another glowing reference from my neighbour (feel free to mention "George, near Whithorn"). Solar and Wind were not the cheapest, but they were the only firm whose surveyors actually knew what they were talking about and could provide in-depth answers. Four years later, George still says the investment in quality, reliability and service was well worthwhile.


    73 from Ian GM3SEK
    Ken G3SDW likes this.
  13. MM5AHO

    MM5AHO New Member

    Ian, thanks for the leads. Valuable.

    I've had discussions with two installation companies now. One sells a good panel with high specs, and what appears a good inverter (recently acquired by ABB). The other is to visit this week, and I'll have their proposal soon after.
    Its interesting speaking to sales people like this though, and seeing the level of understanding of the product they sell. I don't claim to be any expert in solar technology, but my general electrical and electronic knowledge seems to run these guys ragged. It's pretty clear (and perhaps understandable) that they don't know any basic electrical theory. Noticing for example, a good power factor claim on a spec sheet, I played "daft laddie" and asked what that meant. Rather than admit he didn't know, I got a convoluted story about how its a pricing mechanism by generators based on loads across a network. In a way it sort of is, but he didn't really understand concepts of voltage and current being out of phase with each other.
    When asking about mounting bracketry, I got a confused picture that demonstrated a lack of understanding of the difference between anodized aluminium, galvanized steel and stainless steel. When asked what grade of stainless I got a blank look. (turns out to be 304). When mentioning my concern of dissimilar metals corrosion, an even blanker look. Fortunately they bring catalogues, and spec sheets, so I can read the info and make some sense of it all.
    But its easy to see how these guys could get classified alongside double glazing sales people!
    Ken G3SDW likes this.
  14. G3VNH

    G3VNH New Member

    Ken,


    I am again considering the installation of a solar PV system. I currently have 5 other installations in close proximity but they do not cause me any problems. My 4 element beam at 40ft is fed with LDF 4-50 and my trap dipole at 30ft with Eco Flex 10, so a reasonable ‘immune’ antenna system! My property was completely rewired 4 years ago to the latest standard.


    I wonder if the Society or members have any real information on which inverters to specify and certainly the ones to avoid. I have read the postings of G3PGA.


    My original look into this installation was for a SMA Sunny Boy inverter. I was lead to believe that they are good in not producing ‘interference’ and that amateurs in Germany had found no real problem with them. However during further investigation by the supplier (I provided him with all the information from the Society at that time about the problems of Solar installations and he contacted the UK supplier for SMA products only to be told ‘a radio amateur, Ohhh!!!!’ I then decided against going ahead.


    Any information would be useful as I do not really wish to generate my own interference! I understand that you may not be able to provide names etc. because of confidentiality.


    Thanking you for you time in dealing with this matter.


    PETER HARDY

    G3VNH

    CHESTERFIELD
  15. Ken G3SDW

    Ken G3SDW Moderator

    Hi Peter, i seem to be busy with this subject this week and have just had some good news about a member who was in your position earlier this year, what he has said may be of some help to you.
    He has said,

    The system has now been installed by Absolute Renewable Energy (UK) Ltd
    and consists of 6 + 10 PV panels and an Aurora inverter system. I can
    see nothing obvious added behind the panels and when I mentioned
    "conditioner" to the installers that resulted in blank looks.

    The level of interference detectable on the inverter cables is low, and
    the overall addition to the general background RF noise levels is very
    low. Incidentally, much of the RF noise on the lower frequencies seems
    due to the overhead telephone cables.

    73, Roger G3MEH


    Hope this is imformative for you.

    73
    Ken
    G3SDW
    EMCC

    Annesley Nottinghamshire
  16. MM5AHO

    MM5AHO New Member

    I'm in a similar position, as described above in this thread. I'm hoping to place an order very soon.
    In speaking to several companies (I'm getting 3 quotes) I've mentioned this issue to them all.
    In one company I'm dealing with a gut who doesn't really understand the difference between ac and dc. (sales guy). In another I'm dealing with a graduate engineer in electronics. This variety means a huge variation in knowledge level.
    One company trotted out a reference from a guy, who had put his callsign on the document (actually a print from a website). The reference is good, but a bit deeper digging shows that the guy has not been on air for 3 years, so hasn't really proven his ENC condition on his 18 month old installation.
    The sales guy claimed that this amateur has suffered no EMC issues. That's true, and if I do not switch on my RX then I'll suffer none too perhaps!

    I'm still in progress of discussions and tests, but will post results here. I'm checking out the Aurora (recently acquired by ABB) on Monday, and a SMA Sunny Boy this afternoon.
    Geoff
  17. colinsanter

    colinsanter New Member

    Hi Geoff,
    I have a 4kW solar PV system on the roof of my house, with an inverter in the roof space. All of my antenna's are within 30 feet of the solar PV system.
    My solar PV installation is over three years old now, and I have not noticed any interference to any of my HF, VHF, or UHF equipment.

    I spent a long time researching the various makes and compatibility of the equipment available to get the most efficient system. My conclusion was that a good impedance match between the panels and the inverter is important for the efficiency of the system and minimising any risk of RF radiation.

    The system I purchased, comprises a SMA Sunny Boy inverter, and 16 X 250 Watt Mitsubishi solar PV panels.

    My advise: DO NOT buy cheap, buy the best inverter, panels and installation you can afford, ask the installer to run all the DC and AC cables in metal conduit instead of plastic, and bond the conduits to earth.
    Enjoy the lower electricity bill and the FIT income.
  18. Ken G3SDW

    Ken G3SDW Moderator

    Thanks Colin for your input, this is exactly what this forum is about.
    Cheers
    73
    Ken
    G3SDW
    EMCC
  19. MM5AHO

    MM5AHO New Member

    Update on my installation:

    After much research into makes and models of panels and inverters, I opted from LG Electronics panels and an SMA Sunny Boy SB3600TL inverter.
    Its been on line only 3 days, of which one was heavy rain, and two some sunshine.
    Only today have I been home during some sun, to see if there's any detectable RF.
    So far on all HF bands I can't detect anything. Using a variety of antennas, all in fairly close proximity to the system, no RF. The inverter is located about 3m from my operating station and rig. Nothing on 2m band either.
    It might be too soon to declare this a total success, but it looks very encouraging.

    I was surprised to find it exporting 200W as the sun came up this morning, and despite the WX here today being somewhat misty and with light cloud, the system peaked at 2kW export (rated 3.92kW peak).
  20. Ken G3SDW

    Ken G3SDW Moderator

    Good news Geoff, very good indeed. lets hope it stays that way which it should do of course.

    Pop back from time to time if you could just to give us a brief update.

    Many thanks for your input.

    73
    Ken
    G3SDW
    EMCC

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