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  1. #16
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    Quote Originally Posted by jhovel View Post
    I really see no correlation in your graph to sunshine.
    Good observation Joe. However, that isn't the phase my inverter is connected to. I posted that one because it had a large variation in max and min voltage to demonstrate how wildly voltage fluctuates. I've attached another trace with inverter power vs voltage for the connected phase. You can see a definite drop in V when cloud covers the sun and an increase in V when the sun comes out again. But there are also voltage swings that are unrelated to solar output.

    I get an email every time my inverter has to throttle back due to over-voltage. That doesn't happen very often these days, but when it does it's always when the inverter is pumping out a lot of power.
    Attached Images Attached Images
    Chris

  2. #17
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    Quote Originally Posted by .RC. View Post
    The sillybit was not referring to you,
    Fair enough.

    Quote Originally Posted by .RC. View Post
    There used to be a solar cell manufacturing plant in Sydney. Where is it now?
    China or South Korea I guess. Realistically though, we were never going to be able to produce solar panels that were affordable. I believe the Germans are now out of the game too. Even with the government rebate my South Korean panels were expensive.
    Chris

  3. #18
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by .RC. View Post
    You only have to google about the working conditions and environmental destruction caused by mining rare earth elements and other things needed by the renewable market and suddenly it is not such a great thing. Rare Earth elements are not rare, but the processing of them and making them still to be easily affordable can only be done when it does not matter if your workers are poisoned or killed.
    REE are not used in Solar panels

    There is a very wide range of metals used in solar panels and many are used in minute quantities. These are, in alphabetical order: Arsenic (used in semi-conductor chips), Aluminum, Boron minerals (used in semi-conductor chips), Cadmium (used in certain types of cells), copper (used in wiring and certain types of cells), Gallium, Indium (used in cells), Iron ore (steel), Molybdenum (used in photovoltaic cells), Phosphorous, Selenium, Silica, Silver, Tellurium, and Titanium.
    Interestingly REE are used in petroleum distillation.
    while a crucial process in the conversion of petroleum into gasoline uses lanthanum and cerium.
    The vast majority of REE use is as a catalyst for petrochemical and other processes
    The amount of REE used to crack petrochemicals into petrol for the lifetime of a vehicle is about the same as the amount of REE needed in the batteries and magnets needed by electric vehicles.
    app2.jpg.gif

    The batteries of most hybrid gas-electric vehicles use magnets that include quantities of dysprosium and neodymium.
    But the major elements in battery use are of course Li and Pb all of which including the REE are highly recyclable.

    Uses of REE see Rare earths: uses, applications-Metalpedia

    Ag and Te (3 times rarer than gold) are expected to be the main metal cost limitations in PV production - buy your tellurium mining stocks here. Fortunately the excess Ag from the no-longer used Ag in photo film has found a new home and apparently it won't be long before the demand for Ag in PV exceeds the peak Ag use in the era of film based photos.

    BTW I don't have any solar panels and no plans to buy any either.

  4. #19
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    That's a really interesting graph, Chris. I had not expected that.
    Since you ar obviously interested in this, are you able to overlay all three phases - and maybe your inverter output as well? I'd be really curious if cloud cover was reflected on all three phases (mainly). The inverter trace isn't voltage - right? - what units is that showing?
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  5. #20
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    Quote Originally Posted by jhovel View Post
    Since you ar obviously interested in this, are you able to overlay all three phases - and maybe your inverter output as well?
    Sure Joe. Here's yesterday's traces. My inverter is connected to the phase shown in yellow. I don't know which phases my neighbours are connected to. The inverter trace is Watts. I managed to cut that off in my previous screenshot. Volts seem to follow Watts when there are abrupt changes in inverter output. Less (no?) correlation when inverter output changes gradually.
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    Chris

  6. #21
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    Hi Jack620,

    The longer term correlation between your inverter's output and the voltage is masked by the power network's operation. The network operators employ automatic voltage control that continuously monitor the network and adjust the voltage to with a 2.5% band. They normally operate when the voltage gets outside the band for 60 to 90 seconds. It can also be masked by how much power you use on the premise.

    The other thing you know is that most panels produce less power as they get hotter. A cloud passing overhead gives them a chance to cool down. When the sun comes out, output climbs and then falls as the panels heat up.

    I have seen voltage swings from 240 to 228 due to an aluminium smelter coming online some 200km away. The aluminium smelter was connected to the state 132,000 volt system and was driving the entire states grid up and down as it went on and offline. It was all sorts of funny/sad attempting to explain to a small shop owner why he had a problem. Took a bit to convince skeptical bosses, at least at first. That was a long time ago and I doubt that still happens.

    Solar generation does travel into the high voltage system and can do for very long distances.

    The electricity networks were designed and built when the idea of customers generating power back into the grid would have been considered lunacy. Changing the designs and operation of the systems is a slow process. A lot of money invested in the infrastructure, a lot of people adversely affected if you make sudden poor planning decisions.

    What will drive people off the grid is poor politically motivated decisions abouth the cost of power etc. Batteries get cheaper by the day. Aggragate roof top PV is the largest generator on about 115,000 buildings or about 1 in 4 houses. If prices get too high people will go off grid. Take away the 44 cent infeed tarriff inspires all those people to go off the grid. This is a minefield that no angel would enter.

    Renewables are not as variable, en masse, as many suppose. Sure if it's cloudy at my place solar output drops, unlikley to be cloudy at both your place and my place at the same time if we live 1000km apart, thus the greater the number of renewable generators the less the variabilty. Sure when the sun goes down PV stops. Batteries will solve that. Also because of the geographic spread network reliability improves.

    I experienced a powerpoint presentation today ( I barely survived the 5.5 hours of it and have the mental scars to prove it) Apparently the network specs are 230Volts +- 10%

    Cheers

    The Beryl Bloke
    Equipment er.... Projects I own

    Lathes - Sherline 4410 CNC
    Mills - Deckel FP2LB, Hardinge TM-UM, Sherline 2000 CNC.

  7. #22
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    Hi Beryl,

    Can you explain how peoples rooftop PV power gets injected back into the high voltage supply?

    If it gets injected into the grid in peoples homes at roughly 230v then where and how does it get up converted to HV again?

    If its already mixed in with 230v power that has been down converted from the HV supply then why would you invert it back to HV?

    I dont understand.

    Simon

    Sent from my SM-G900I using Tapatalk
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  8. #23
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    Default Low voltage Solar to high voltage

    Quote Originally Posted by simonl View Post
    Hi Beryl,

    I dont understand.

    Simon

    Sent from my SM-G900I using Tapatalk
    Hi Simon,

    The previous normal power flow was that it was generated in large power stations and then stepped up to 132,000 volt (or 275,000 volt) transmission lines. Those lines are the backbone of the network. They run to what is referred to as a "bulk supply" substation where the 132,000 volts is stepped down to "Sub-transmission" voltages generally 33,000 or 66,000 volts. The voltages fed into the sub-transmission lines are automatically regulated. Those sub-transmission lines then feed local zone substations where the 66,000 volts is again reduced to 11,000 (or possibly 22,000) volts, this voltage is also automatically regulated. So the voltage here is essentially fixed.

    The 11,000 volt line feeds the distribution transformer near your house that steps the voltage down from 11,000 to 415/240 volts. That step down is not automatically regulated and is fixed (for arguments sake). Transformers are very efficient at converting power from one voltage level to another. However they really don't care in which direction they are converting it, they step up as well as they step down, no questions asked.

    Voltage drop in a conductor is calculated as the current through the conductor (in amps) multiplied by the resistance of the conductor (in ohms) Thus your electric hot water system might draw 15 amps and the resistance of the conductors between your distribution transformer and the hotwater system might be 0.4 ohms thus the voltage drop at the hot water system is 6 volts.

    Lets assume you are the only person connected to your local distribution transformer. Your solar system is generating 15 amps back into the grid. That reverses the process and causes the voltage to rise at the inverter by 6 volts. As the power can't be used locally, your inverter will continue to force current into the mains raising the voltage a little more and in doing so back energises the local distribution transformer (which doesn't care) and raises the voltage on the 11,000 volt distribution line.

    For sure a single inverter won't do much. They are set to trip off at around 256 volts. En masse? that's quite different. I am aware of situations where long rural 11,000 volt feeders have been forced up to 265 volts at transformer terminals. Sometimes, automatic voltage regulation, is installed in long lines and I have seen it stop working when the power flows in the "wrong" direction. I have not seen, nor know of, any situations where power flow through a 66,000/11,000 volt Zone substation has reversed. I doubt that situation could arise under current restrictions on solar, however, I am curious about this now and will chat to my friendly local engineer. I suspect this situation might not end well !

    Issues of inverters dropping off line because the volts get too high are due to too much resistance in the lines between the inverter and the distribution transformer. Usually this means the sizes of wire is too small or the distances too great. Thus the best advice I can offer anyone thinking of putting on Solar is to have their proposed installer do what is called a "loop impedance" test (this tells you the resistance of the circuit) at the proposed location of the inverter and have them calculate the voltage rise at full inverter output. If your installer hestitates, find another installer. This can save everyone a lot of angst later.

    Sorry for the long post. If you need clarification on anything, more than happy to provide it. Also apologies if I have made it soo simple or too complicated

    Cheers

    TheBeryl Bloke
    Equipment er.... Projects I own

    Lathes - Sherline 4410 CNC
    Mills - Deckel FP2LB, Hardinge TM-UM, Sherline 2000 CNC.

  9. #24
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    Thanks for the reply Beryl. Learnt some more stuff!

    Simon

    Sent from my SM-G900I using Tapatalk
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  10. #25
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    Another issue is nasty harmonics being generated. I have read power these days is dirtier then in times past. Amateur radio people really notice it.
    Gold, the colour of choice for the discerning person.

  11. #26
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    what ??? !!!! if the name tag says it will work on 220 then I reckon it will work on 240. does for me...

  12. #27
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    Quote Originally Posted by .RC. View Post
    Another issue is nasty harmonics being generated. I have read power these days is dirtier then in times past. Amateur radio people really notice it.
    and they create the most interference...but hey I like them

  13. #28
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    Quote Originally Posted by eskimo View Post
    what ??? !!!! if the name tag says it will work on 220 then I reckon it will work on 240. does for me...
    I agree Eskimo, but if the seller has doubts, I don't think that I'll take the chance, especially when BobL points out a superior alternative, for not much extra! I was quite surprised to get the reply from the seller that I did, when all I was really after was for them to put in writing that the device was suitable for use on Australian mains supplies. I do feel a little uncomfortable when manufacturers quote an input voltage requirement of say 220 volts plus or minus 10%, which leaves virtually no headroom if the local supply is 240 Volts. In the old days, I have seen voltages above 250V, but in the last couple of days it was around 232 to 234 volts. Today it is 239.7 volts according to my fairly cheap and never calibrated Digitech QM1539 multimeter which cost IIRC about $40 about 10 years ago. The talk of our voltage being harmonised with the rest of the world, and being lowered to 230V, isn't ringing true to me, it seems more a case of them loosening the specification, to make life easier for the generators and power distributors, and make it harder for consumers to claim damages against them for electrical events caused by over or under voltage electric supply.
    Rob.

  14. #29
    BobL is offline Member: Blue and white apron brigade
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    If you want to buy a VFD that claims to be rated for 240V then try these Folinn VFDs from an Australian Supplier.

    A 2HP unit costs $235 and is a full vector drive - being an Aus supplier is a plus.
    https://www.ebay.com.au/itm/1-5kw-2H...-/172761255022
    I don't believe they are quite as good as the Powtran 9130 series but still a respectable unit.

    The seller makes a big deal of saying they are rated and warranted for 240V +/- 15%

    If you go to the Folinn website you'll see these VFDs are rated at 220 +/- 15% and I doubt the factory would change anything for a small australian supplier.
    My guess is they already use reasonably well rated components and just change the sticker to reflect what the Aus buyer wants. This is fairly common from chinese suppliers.


    .

  15. #30
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    Default "Dirty" power

    Quote Originally Posted by .RC. View Post
    Another issue is nasty harmonics being generated. I have read power these days is dirtier then in times past. Amateur radio people really notice it.
    Well it's not just the PV inverters. Everything has a non-linear switchmode power supply because they are cheaper. When was the last time anyone here bought an item with a step down\up transformer & full wave rectifier power supply? early 80's probably. A VFD is essentially a non-linear switchmode power supply as I understand it (see, still on topic)

    I'm told the fun really starts when you have a big office full of PCs with the load nicely balanced across all three phases. Then because they are all switchmode non-linear power supplies you get all of the return curent in the neutral conductor i.e. total load of all three phases. Neutral connections burn out or the insulation melts off the neutral just before the cables burn apart. Easy fix, just replace the neutral conductor with one rated for three times the phase load.

    I have seen the harmonics on an 11,000 volt feeder with heavy solar loads. There seemed to be lots of harmonic voltages present. Interestingly the actual harmonic currents were quite low and did not seem to bear much relationship to the voltages. Highest harmonics were the third and sixth? I have no idea as to the accuracy of the measuring equipment so this is purely anecdotal.

    Non the less I am at a bit of a loss as to how powerline frequency harmonics interfere with ham radio operating at much higher frequencies. Not saying it doesn't happen just personally ignorant.

    Cheers

    The Beryl Bloke
    Equipment er.... Projects I own

    Lathes - Sherline 4410 CNC
    Mills - Deckel FP2LB, Hardinge TM-UM, Sherline 2000 CNC.

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